September 2005

I began work on this guide a few weeks ago. Little did I know how much life would change after Hurricane Katrina visited the Gulf Coast last week. The loss of life is unprecedented, as is the extent of the damage. Historically hurricanes have had little economic impact except for the area that is directly impacted. However, unlike prior Hurricanes Katrina is and will have lasting effects on the U.S. economy. The most significant national economic fallout is due to Katrina's impact on key energy assets along the Gulf Coast. An amazing 30% of the nation's oil supplies flow through Louisiana. The Gulf Coast is the source of about 10% of the nation's refining capacity, so gasoline prices have soared. Some analyst's project average pump prices to be $3 per gallon or more during the upcoming Labor Day weekend and to rise a bit more in the fall. Crude prices have also spiked and appear poised to go higher since production in the Gulf is shut in and this represents 25% of domestic capacity.

With gas prices breaking all previously held records in many areas of the country there are a few things each PT owner can do to help ensure that they are obtaining optimal fuel economy with their vehicles.

If you think gasoline is expensive here in the U.S. check out this MSNBC article (PDF) which discusses how much gasoline costs in other countries.

The majority of owners who write to us at PTDoItYourself.net report that they purchased their PT primarily because of the unique look of the vehicle, not for the fuel economy. Of course, as recently as a year or two ago, gasoline was reasonably priced, which made the PT's mediocre mpg numbers somewhat disappointing, but still palatable for most owners. However, what was acceptable then is no longer acceptable today. We need a plan to improve our fuel economy and or reduce our fuel costs, so that our 15 gallon $45 fill-up goes as far as possible when were out on the highway.

Not sure what your mpg is, or how much you spend annually on fuel? Click here before reading any further.

We're anxious to hear about your mpg results once you've implemented some of the recommendations provided below. Please use this form to report results, or review the latest feedback reported by owners here.

Fuel economy is affected by a number of factors, some of which we have little control over and others we can change or improve upon. The biggest factor is the vehicle we choose to drive and its fuel economy characteristics. We can't do much about that, other than exchanging the PT for a vehicle with better fuel economy, so let's try to focus on ways to maximize our fuel economy with the PT.

One fuel saving approach that each driver can apply is to modify their driving habits. Here are some commonsense tips to consider and implement during your daily commute:

• EPA fuel economy highway tests are conducted at an average speed of 48mph; higher speeds, like 65-80mph consume much more gasoline. Driving at 65mph, rather than 55 mph, increases fuel consumption by 20%. Driving at 75mph, rather than 65mph, increases fuel consumption by another 25%.



• Use the cruise control when practical; it helps maintain a constant speed and in most cases, helps reduce fuel use.



• Use smooth, safe starts and stops. A pattern of "rabbiting" through traffic with sudden stops and squealing accelerations reduces fuel by as much as 33% at highway speeds and 5% around town. This can cost you as much as $0.49 per gallon.



• When possible, plan to combine errands into one trip. Several short trips taken from a cold start can use twice as much fuel as one trip covering the same distance when the engine is warm. You'll not only save fuel, but also reduce wear and tear on your car.



• Anticipate traffic conditions and don't tailgate. Eliminating tailgating from driving habits and the resulting unnecessary braking and acceleration can improve fuel economy by 5 -10% and reduce wear on tires and brakes. Nearly 50% of the energy needed to power a car goes into acceleration.



• When highway driving, use your overdrive gears; overdrive decreases the vehicles engine speed, reducing fuel consumption and engine wear.

Always keep safety in mind when experimenting with new driving habits, not to impede traffic, etc.

 

Other Fuel Saving Tips

 

Aerodynamics

Accessories, ground effects, spoilers, etc. can alter the vehicles' aerodynamics. Avoid driving with an open sunroof or windows at highway speeds. Aerodynamic drag reduces mpg by up to 8%. Fresh air can be provided for the occupants by using the vehicle's flow-through ventilation system. Avoid packing items on top of the car. A loaded roof rack or carrier creates wind resistance and can reduce mpg by up to 5%. It's better to place items inside the vehicle.

 

Cash Back Gas Credit Card

Save money on gas purchases by obtaining a Cash Back Gas Credit Card. Discover is offering a new Discover Platinum Gas Card that earns an Cash Back reward of a full 5% of your first $1,500 in gas purchases; your second $1,500 in gas purchases earn 3% and gas purchases in excess of $3,000 earn 1%, with no annual fee, special introductory 0% APR rates, and acceptance at a number of gasoline retailers. You can also double your Cashback Bonus when you redeem for gift cards or certificates from many of Discovers 45 brand name partners. If you can pay your monthly bill off each time you receive it this can be a cost effective way to lessen the fuel bite. Make sure to thoroughly review the terms and agreements before you make a decision to sign up for a card. Check out the Discover® Platinum Gas Card here.

 

Excessive Idling

The USDE estimates that for 145 million passenger vehicles idling 5 minutes per day, approximately 4 million gallons of gas are consumed without going anywhere. Shut the engine off if you're going to be stopped for more than 30 seconds. The PT consumes more fuel when idling over 30 seconds than it does to start the vehicle. Instead of going through the drive through at the local fast food restaurant or dry cleaner, park the PT and walk inside. You'll save fuel and the extra physical activity will help burn off your meal.

 

Extra Cargo

Remove any cargo that is not needed. Every 200 pounds of unnecessary weight reduces mileage by one mile per gallon.

 

Fuel and Octane

A vehicle's fuel economy depends on the energy content of the fuel on which it runs. This has been determined by EPA and others and is consistent with combustion theory. Ethanol blended fuel may decrease mpg by about 2%. MTBE (Methyl Tertiary-Butyl Ether) oxygenated fuels reduces mpg by about 2-3% because they contain less energy than non-oxygenated gasoline. In addition, the energy content of gasoline varies from season to season. Typical summer conventional gasoline contains about 1.7% more energy than typical winter conventional gasoline.

Octane ratings measure a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders.

Most gas stations offer three octane grades: regular (usually 87-octane), mid-grade (usually 89-octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.

Stock PT's should use 87-octane fuel for optimum mpg. PT's with a supercharger or turbocharger should use 92-octane. Expensive high-octane gasoline (premium) does not give your car more power or better mpg. According to the AAA premium gasoline sells for an average of 17 cents more per gallon than regular gas. Only about 6% of cars sold in the U.S. need premium gas. Still, premium gas accounts for 20 percent of all gas sold. Resist the urge to buy higher-octane gas for "premium" performance.

The only reason to use high-octane gasoline is if your car knocks or pings on your normal grade of gasoline, and your mechanic has been unable to find any other easily fixable cause. The PT uses a "knock sensor", which detects knocking and protects the engine by retarding the ignition timing, however it can't compensate for a severe malfunction, a condition which can affect engine performance, fuel economy, or even damage the engine.

 

Terrain and Weather Conditions

Driving on hilly or mountainous terrain or on unpaved roads can reduce fuel economy. Expect up to a 10% drop in mpg in heavy rains, and 1-2% for every 10 degree Fahrenheit drop in temperature.

 

Towing

MPG may be reduced by as much as 10% when towing.

 

Mechanical Condition of Vehicle

The mechanical condition of a vehicle plays ones of the most significant roles in determining fuel economy. If you've owned your PT for awhile and followed the factory recommended maintenance schedule you're probably in pretty good shape, but your diligence places you in a small select group of owners.

Unfortunately, many owners perform little or no maintenance until a problem arises, at which point the cost of the repair and daily operational cost of the vehicle far exceeds the amount of money they would have spent on periodic maintenance. Under inflated tires, vacuum leaks, faulty thermostats, worn spark plugs, malfunctioning engine controls, poor wheel alignment and transmission issues are among the conditions that cost consumers millions of dollars in wasted fuel on a daily basis.

The following are some of the diagnostic checks that a technician will typically conduct for poor fuel economy:

• Perform "On-Board Diagnostic" system check to identify failing sensors, actuators and system malfunctions.



• Check for dragging brakes



• Check transmission shift patterns for slipping, use of all gears and lock-up operation.



• Check owner's driving habits including A/C usage



• Check vehicle load for excessive weight.



• Check emission control system.



• Check vacuum hoses for leaks, kinks and proper routing.



• Check tire condition and pressure.



• Check for correct fuel type, fuel pressure and fuel system for leaks.



• Check air cleaner element.



• Check cooling system for proper operation.



• Check ignition system for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits, cracking or improperly connected ignition wires.



• In extreme cases, there may be engine problems such as poor compression or faulty fuel injectors which need to be checked.

Let's look at a few things we can do, check or repair ourselves (DIY), or economically have serviced by an auto professional to improve MPG on our PT's.

 

A/C System

The engine powers the A/C compressor, which reduces fuel economy. Limited, informal tests by EPA have shown a fuel economy reduction of roughly 5-25% when operating the air conditioner on "Max," compared to not using the A/C. When possible, use air vents to circulate the air instead of the A/C. Rolling down the windows seems like a natural compromise, but also creates aerodynamic drag, which reduces MPG by 5% or more.

Fuel economy is also affected during the colder months. Like many vehicles, the PT's A/C compressor operates in both Mix and Defrost, or a blend of these Modes, even if the fan switch is not in the A/C position. This dehumidifies the air to help dry the windshield. To improve economy, use these modes only when necessary.

To maintain the performance level of the heating/air conditioning system, the engine cooling system must be properly maintained. The use of a bug screen is not recommended. Any obstructions (dirt, insects, etc.) in front of the radiator or condenser will reduce the performance of the air conditioning and engine cooling systems. Maintain these areas by cleaning with a gentle water spray from behind the radiator and through the condenser.

The heating/air conditioning system pulls outside (ambient) air through the cowl opening at the base of the windshield, then into the plenum chamber above the heating, ventilation and air conditioning (HVAC) housing. Check the cowl opening periodically to ensure that there are no obstructions such as ice, slush and snow during the winter months, and leaves and twigs during the remainder of the year, which can reduce air flow, plug the plenum water drains and occasionally work their way down to the blower motor cage to create a pesky amount of noise.

Some later model year PT's are equipped with an air conditioning system air filter. The filter is mounted under the hood in the outside-air intake (bottom of windshield, passenger side) of the HVAC housing. The filter should be checked and replaced at least once every 15,000 miles and checked if A/C-heater system performance seems lower than expected.

Review the guides below for additional information.

Pit Area Resources

A/C Vacuum System Diagnostic
A/C System & Diagnostic Guide
A/C Odors & Treament

 

Engine Cooling System

The cooling systems primary purpose is to maintain engine temperature in a range that will provide satisfactory engine performance and emission levels under all expected driving conditions. The system does this by transferring heat from the engine metal to the coolant, than moves this heated coolant to the radiator where this heat is transferred to the ambient air. The cooling system also provides hot water (coolant) for heater performance and cooling for the automatic transmission oil.

The PT's cooling system consists of an engine cooling module, thermostat, coolant recovery/reserve system, coolant, and water pump. The engine cooling module consists of a radiator, electric fan motor, fan, shroud, transmission oil cooler, hoses, clamps, air conditioning condenser and transmission oil lines.

Turbocharged equipped PT's utilize an additional radiator in-tank cooler for a power steering fluid cooler.

Cooling system neglect is cited as a principal reason for the mechanical failure of most vehicles. In addition to the danger and inconvenience of a breakdown, damage to the engine and transmission can add up to thousands of dollars. Discovering a leaking radiator, hose connection, sticking thermostat or other cooling system component that's borderline-operational can save the life of ones engine. It has been widely reported that the two primary components responsible for engine overheating issues are the thermostat and coolant.

Engines are designed to operate within a specific temperature range for optimum efficiency. A properly functioning thermostat with the correct heat range is absolutely essential for proper emissions control, good fuel economy and performance. A thermostat that causes the engine to run too cold can experience up to a two mpg loss in fuel economy.The thermostat resides in between the engine and radiator and acts as a temperature controlled engine coolant valve. When the engine is cold the thermostat is closed and the cooling system has no flow through the radiator. The coolant flows through the engine, and heater system, which also serves as the bypass. When the engine is warm the thermostat is open and the cooling system has flow through the radiator, engine, and heater system, which also serves as the bypass.

Good quality thermostats generally have a service life of 2, 3 or more years, but when they fail, usually at the most inopportune time, the result is often an overheated engine. If the engine overheats, detonation can occur, and is often accompanied by a loss of power. If detonation persists, damage to the rings, pistons, and rod bearings often occur. A blown head gasket can also be a consequence of overheating. Heat makes aluminum swell almost three times faster than cast iron. The resulting stress can distort the engines head and make it swell in areas that are hottest, like those between exhaust valves in adjoining cylinders, and areas that have restricted coolant flow, like the narrow area that separates the cylinders. The typical aluminum head swells most in the middle, which can crush the head gasket if the head gets hot enough. This will cause a loss of torque in the gasket, allowing coolant and combustion leaks to occur when the head cools.

A cylinder head gasket leak can be located between adjacent cylinders or between a cylinder and the adjacent water jacket. Misfires in adjacent cylinders, loss of power and poor fuel economy often indicate a leaking head gasket between adjacent cylinders. Possible indications of the head gasket leaking between a cylinder and a adjacent water jacket are engine overheating, loss of coolant, excessive steam (white smoke) emitting from exhaust and coolant foaming. A Cylinder Compression Pressure test can be performed to determine if an engine cylinder head gasket is leaking between adjacent cylinders and other procedures are available to test for cylinder to adjacent water jacket leaks.

Severe overheating can often damage a good thermostat by damaging the wax element inside the thermostat. If the engine has overheated because of another problem, the thermostat should be replaced as a precaution before the engine is returned to service. The thermostat housing should also be inspected and replaced it if it is badly corroded, warped or cracked. The engine coolant temperature sensor should also be checked to make sure it has not been damaged.

The engine coolant temperature (ECT) sensor threads into the thermostat housing just below the coolant outlet connector. The ECT Sensor is a Negative Thermal Coefficient (NTC) Sensor. The resistance of the ECT Sensor changes as coolant temperature changes. This results in different input voltages to the PCM. The PCM also uses the ECT Sensor input to operate the radiator cooling fan(s), and send a message over the PCI bus to the instrument cluster for temperature gauge operation. A compromised sensor can cause rough running, rough idle and poor mpg.

The PT's Engine Temperature Warning Light will light up if the engine experiences an overheated condition. If the engine is critically hot a continuous chime will sound for 4 minutes. After the chime stops the engine will still be critically hot until the light goes out. At the first sign of overheating (temperature pointer on gauge rises to H red indicator) it is imperative that the driver (safely) pull off the road as soon as possible. Once stopped, a quick way to reduce the overheating condition is through the use of the vehicles' HVAC system. With the engine idling, and the A/C turned OFF, adjust the Temperature control to maximum heat, the Mode control to Floor and the Fan control to High. This allows the heater core to act as a supplement to the radiator and aids in removing heat from the engine cooling system. Let the PT cool down and try to resolve the issue before resuming further use of the vehicle.

If the thermostat is faulty and needs to be replaced, install one with the same temperature rating as the original. When possible, we recommend using an OE Mopar replacement, based upon trouble reports we have received from owners using so-called aftermarket equivalents. Using a different temperature rated thermostat in an attempt to "cure" a cooling issue can increase fuel and oil consumption, ring wear and emissions. On vehicles like the PT, with computerized engine controls, the wrong thermostat can prevent the PCM from going into closed loop, resulting in major performance and emission problems if the engine fails to reach its normal operating temperature.

The PT's engine-cooling thermostat is a wax pellet driven, reverse poppet choke type. The thermostat is designed to provide the fastest warm up possible by preventing leakage through it and to guarantee a minimum engine operating temperature of 192 to 199°F. The thermostat will also automatically reach wide open, so it will not restrict the flow to the radiator as the temperature of the coolant rises in hot weather to around 220°F. Above this temperature the coolant temperature is controlled by the radiator, fan and ambient temperature, not the thermostat.

When coolant reaches a predetermined temperature, the wax expands enough to overcome the closing spring and water pump pressure, which forces the thermostat to open. Coolant leakage into the wax pellet will cause a thermostat to fail in the open position. When a thermostat is in the stuck open position the engine will not operate at the proper temperature for optimal engine fuel efficiency, performance and emissions levels.

A thermostat that is stuck in the open position can cause the engine to run too cool, and reduce mpg by up to 7%. Symptoms of a faulty (weak or open) thermostat may include an engine that does not warm up (temperature gauge – reads low), an engine that warms up too slowly, a DTC indicating a stuck open thermostat, a heater that puts out only warm or cool air, poor engine performance, or an incorrect replacement thermostat.

Symptoms of a thermostat that may be partially or completely closed may include a temperature gauge that reads high, a lit engine coolant warning lamp (coolant may or may not be lost from system), a temperature gauge that steadily climbs, but does not decline.

According to numerous aftermarket surveys that have been performed over the years, coolant neglect is one of the leading causes of cooling system breakdowns. One reason for checking the coolant level regularly is to detect leaks that can lead to overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head and block.

The PT's coolant recovery/reserve system provides a quick visual method for determining the coolant level without removing the pressure cap. Simply observe, with the engine idling and warmed up to normal operating temperature that the level of the coolant in the recovery/reserve bottle is between the FULL HOT and ADD marks.

Although the coolant is within a closed system, most vehicles will lose a little coolant over time due to evaporation from the reservoir. A significant loss of coolant in a relatively short period of time usually signals a leak, a radiator cap that isn't holding pressure or a cooling system that's running too hot. Visually inspect the radiator, water pump, hoses, freeze plugs, etc. for external leaks, and then pressure test the radiator and cap to find out where the coolant is going. If no leaks are found, the loss of coolant may be due to long-term neglect or a temporary episode of overheating. A defective cooling fan, slipping drive belt, exhaust restriction (plugged converter) or even overloading the engine may have caused the system to get too hot and boil over.

When you add or replace coolant in the PT, the use of Propylene Glycol based coolants is not recommended, as they provide less freeze and corrosion protection.

The use of aluminum heads and water pumps requires special corrosion protection. Chrysler recommends using Mopar Antifreeze/Coolant, 5 Year/100,000 Mile Formula or equivalent ethylene glycol based coolant with corrosion inhibitors (called HOAT, for Hybrid Organic Additive Technology).

This coolant offers the best engine cooling without corrosion when mixed with 50% Ethylene Glycol and 50% distilled water to obtain a freeze point of -37°C (-35°F). If it loses color (orange) or becomes contaminated it should be drained, flushed, and replaced with a fresh properly mixed coolant solution. Mixing of coolants other than specified (non-HOAT), will reduce the 5 year/100,000 mile corrosion protection. Green coolant must not be mixed with the orange or magenta coolants. Doing so will reduce the corrosion protection and may result in premature water pump seal failure. If a non-HOAT coolant is introduced into the cooling system in an emergency, it should be replaced with the specified coolant as soon as possible. When replacing coolant a complete system flush must be performed before using the replacement coolant.

The antifreeze in the coolant performs three very important jobs: it prevents the coolant from freezing during cold weather, it raises the boiling temperature of the coolant to prevent overheating during hot weather and it fights corrosion.

Besides checking the level of the coolant periodically to make sure it isn't low the strength and condition of the antifreeze should also be checked.

The coolant concentration should be checked with a hydrometer or a refractometer when any additional coolant is added to system or after a coolant drain, flush and refill. The coolant mixture offers optimum engine cooling and protection against corrosion when mixed to a freeze point of -37°C (-34°F) to -46°C (-50°F).

Some auto enthusiasts use a chemical test strip to help test the condition of antifreeze, which shows how much reserve alkalinity (which prevents corrosion) is left in the coolant. The test strip changes color when dipped in the coolant, which allows you to compare the color against a reference chart to determine the coolant's condition. To get an accurate reading, make sure that you know what kind of coolant is in the system; then use the appropriate test strips to check it. Otherwise the use of a refractometer provides the most accurate method for determining the condition of unknown antifreeze. If the coolant tests bad or is close to borderline, replace it.

Maintenance schedule B reccomends replacing the coolant at 100,000 miles or 5 years, whichever interval occurs first. However, it is our recommendation that you perform this service every 2-3 years to help maintain optimal performance, prolong the life of the cooling system and reduce the potential of failed components due to old contaminated fluid.

Inspect the condition of the fluid during the drain and fill procedure. If the solution is dirty, rusty, or contains a considerable amount of sediment; clean and flush with a reliable cooling system cleaner. Flushing removes most of the old coolant from the engine block. It also helps dislodge accumulated deposits that can plug heater cores, radiators and interfere with proper heat transfer.

An additional component you want to keep an eye on is the electric radiator cooling fan module. A number of these have failed on the PT. In several instances the fan motor simply failed because of worn motor brushes. The motor is a non-serviceable component, and the fix consists of replacing (expensive) the entire radiator fan module. Review the Top 10 Issues Guide in the Pit area for more information.

Finally, overheating can be caused by anything that decreases the cooling system's ability to absorb, transport and dissipate heat: A low coolant level, loss of coolant (through internal or external leaks), incorrect coolant type, a defective thermostat, poor airflow through the radiator, an inoperative electric cooling fan, a collapsed lower radiator hose, an eroded or loose water pump impeller, or even a defective radiator cap. Please review the cooling systems guides below to help diagnose and repair issues you encounter and or to help maintain your cooling system.

Pit Area Resources

Cooling System & Maintenance Guide
Cooling System Diagnostic
Thermostat Guide
Radiator Guide
Radiator Fan Guide
Top 10 Issues Guide

 

PCV Valve and Engine Air Filter

The PCV (positive crankcase ventilation) valve and engine air filter are often neglected during routine tune-ups, which can lead to a number of drivability problems including the formation of sludge and contaminant buildup, shorter engine life and reduced mpg.

Crankcase emissions have been reduced 100% since 1963. In the early 1960's, positive crankcase ventilation systems were introduced on passenger cars. This simple system used a hose from the crankcase to the engine intake manifold to pull fumes into the manifold. There the fumes could be reburned. A small check valve called the PCV valve (Positive Crankcase Ventilation) was placed in the hose to control the flow of fumes. On the PT the PCV valve threads into the driver side of the valve cover.

This PCV system requires little maintenance. Check the hoses for cracks or soft spots and replace it if necessary, and replace the PCV valve at the manufacturer's recommended mileage intervals. If the hose leaks the engine will idle roughly and sometimes stall. A hose that has collapsed or a sticking PCV valve can allow crankcase pressures to build up and this forces oil out of the engine past the seals and breather passages. An engine air filter filled with oil and or excessive oil consumption usually indicate the PCV system isn't working and it should be serviced immediately.

An air filter that is clogged with dirt, dust and bugs chokes off the air and creates a "rich" mixture - too much gas being burned for the amount of air, which wastes gas and causes the engine to lose power. Replacing a clogged air filter can improve your vehicle's mpg by as much as 10% and keep impurities from damaging the inside of your engine.

We recommendation inspection and or replacement of the engine air filter and PCV valve under schedule B of the service maintenance schedule. If your mileage is currently beyond 90,000 miles please refer to the owners' manual service schedule B for the next scheduled maintenance period.

Engine Air Filter Service Maintenance Schedule
Schedule	Mileage	Mileage	Mileage	Mileage	Mileage	Mileage
	15k	30K	45k	60k	75k	90k
B - All Engines	I&R	R	I&R	R	I&R	R
I&R=Inspect and replace, if necessary. R=Replace.





PCV Valve Service Maintenance Schedule
Schedule	Mileage	Mileage	Mileage	Mileage	Mileage	Mileage
	15k	30K	45k	60k	75k	90k
B - All Engines		I&R		I&R		I&R
I&R=Inspect and replace, if necessary.

The air filter guide also includes a list of suggested aftermarket filters and procedure for inspecting the filter to determine if replacement is necessary.


Pit Area Resources

Engine Air Filter Guide
PCV Valve Diagnostic & Guide

 

EGR Valve

The Exhaust Gas Recirculation (EGR) valve may stick in the open position, fail to close completely or just not operate smoothly. If so, the engine will hesitate and may stall, mpg may drop, and emissions may be affected.

The PT's EGR system reduces oxides of nitrogen (NOx) in engine exhaust and helps prevent detonation (engine knock). Under normal operating conditions, engine cylinder temperature can reach more than 3000°F. Formation of NOx increases proportionally with combustion temperature. To reduce the emission of these oxides, the cylinder temperature must be lowered. The system allows a predetermined amount of hot exhaust gas to recirculate and dilute the incoming air/fuel mixture, which reduces peak flame temperature during combustion and reduces a key pollutant (oxides of nitrogen), but often improves fuel economy.

Symptoms of a failed or malfunctioning EGR system may include engine spark knock, sags or hesitation, rough idle, engine stalling, increased emissions and diagnostic trouble codes P0401 through P0406. If the EGR system operates incorrectly, the EGR valve and transducer must be replaced together since they are calibrated together.

There is no EGR valve on the 2003-2005 PT non-turbo engines. The castings are in place, but no valve, tube, or solenoid. The EGR chapter is missing from the newer 2003-2005 service manuals.

Review the guides below for additional information.

Pit Area Resources

EGR Valve System Guide
Top 10 Issues List

 

Oxygen Sensors

Today's vehicles utilize many types of sensors fulfilling various functions in the various electronic control systems. But the oxygen sensor is the most critical for producing maximum efficiency. Without a properly functioning oxygen sensor the engine's PCM can only guess at the air/fuel mixture. Research indicates that as many as one out of every seven vehicles on the road today needs a new oxygen sensor. A study performed by Sierra Research, Inc., a leading air pollution consulting firm, showed that over half of all vehicles that fail hydrocarbon (HC) and carbon monoxide (CO) emissions tests have oxygen sensors that are either degraded or are inoperative.

This sensor is the master switch in the fuel control feedback loop. The O2 sensor monitors the amount of unburned oxygen in the exhaust and produces a voltage signal that varies from about 0 volts (lean) to 1 volt (rich). The computer uses the O2 sensor's signal to constantly fine-tune and flip-flop the fuel mixture so that the catalytic converter can do its job and clean the exhaust.

On OBDII-equipped vehicles, like the PT, a second O2 sensor after the catalytic converter is used to monitor converter efficiency. If an O2 sensor circuit opens, shorts, or goes out of range, it usually sets a fault code and illuminates the Malfunction Indicator Lamp. But many an O2 sensor that is badly degraded may continue to function well enough not to set a fault code, but not well enough to prevent an increase in emissions and fuel consumption. The absence of a fault code or MIL, therefore, doesn't mean the O2 sensor is doing its job.

The performance of the O2 sensor tends to diminish with age as contaminants accumulate on the sensor tip and gradually reduce its ability to produce voltage. This kind of deterioration can be caused by a variety of substances that find their way into the exhaust such as lead, silicone, sulfur, oil ash and even some fuel additives. The sensor can also be damaged by environmental factors such as water, splash from road salt, oil and dirt.

Worn oxygen sensors cause engine surging, especially upon start up, hesitation when accelerating hard, reduced mpg, and accelerated catalytic converter damage. Replacing a faulty oxygen sensor can improve mpg by as much as 40%, smooth engine performance and prevent premature failure of the catalytic converter, which is an expensive repair.

Review the guide below for additional information.

Pit Area Resources

Oxygen Sensors System Guide

 

Spark Plugs

Spark plugs fire millions of times every thousand miles, which results in excessive heat, electrical, and chemical erosion. Worn spark plugs reduce mpg and impair engine performance. Symptoms may include reduced mpg, loss of power, severe rough idle and misfire fault codes P0300 through P0304. A misfire in one cylinder of a four-cylinder engine is the equivalent of a 25% loss of power, which can waste a lot of fuel and cause a big increase in exhaust emissions.

Misfire can be caused by worn or dirty spark plugs, high resistance in spark plug wires, a weak ignition coil, dirty fuel injectors, low fuel pressure (weak pump or dirty fuel filter) or compression problems.

Inspect the old plugs during the replacement process. If they all have a coating of black carbon, that indicates a rich fuel mixture and likely a bad oxygen sensor. A scan tool should be able to pinpoint a malfunctioning oxygen sensor even if it didn't log a fault code. If there's just a single carbon-blackened plug, you may have a leaking fuel injector.

We recommend a service change for the OE plugs each 30k miles or 3 years, or earlier when dictated by performance issues. Some owners have reported changing their plugs at much earlier mileage because of engine performance issues. Owners can easily access the plugs in cylinders #1 and 4 for inspection prior to replacement to check their condition on the standard PT. Inspection and replacement of all 4 plugs on the GT (Turbo) model is much easier since the upper intake manifold does not have to be removed to access the plugs.

Spark Plug Service Maintenance Schedule
Schedule	Mileage	Mileage	Mileage	Mileage	Mileage	Mileage
	15k	30K	45k	60k	75k	90k
B - All Engines		R		R		R
R=Replace.

If your mileage is currently beyond 90,000 miles please refer to the owners' manual service schedule B for the next scheduled maintenance period.

A number of owners have switched from the OE Champion plug to the Champion Double Platinum plug. This is a plus for PT owners, since the plug replacement procedure is somewhat labor intensive, and Champion guarantees the double platinum plugs for 5 years and unlimited mileage, which provides for longer life between plug changes. PT owners have reported reduced rough idle and better mpg with the Champion Double Platinum plug. The DP plug is recommended for use with OE non-aspirated PT engine only. PT owners with forced induction engines have complained of spark knock (ping) using the Champion DP plugs, therefore, stick with the OE Champion plugs if you have a turbo or supercharger.

You should also consider replacing your plug wires when you replace your spark plugs to avoid problems like hard starting, hesitation, and misfiring.

Review the guides below for additional information.

Pit Area Resources

PT Spark Plug, Inspection & Wire Guide
GT Spark Plug Guide
PT & GT Spark Plug Specification Guide
Spark Plug Tip Guide

 

Oil, Viscosity & Filters

Dirty oil reduces mpg by one mile per gallon and hastens engine wear. As engines wear, they loose compression, and then efficiency. Changing the oil at regular intervals reduces engine wear on internal engine components and can increase fuel economy.

The correct oil filter can influence a vehicle's mpg. Clogged, incorrectly applied, or substandard quality oil filters can reduce mpg. It is important that oil filters are changed at regular intervals and meet manufacturer's specifications to protect vital engine parts and optimize oil pump performance.

We recommend that you change the oil and filter change every 3,000 miles to prolong engine life and improve mpg.

Oil & Filter Service Maintenance Schedule
Schedule	Mileage
B – All Engines	Every 3,000 miles.

"Viscosity" refers to how easily oil pours at a specified temperature. Thinner oils have a water-like consistency and pour more easily at low temperatures than heavier, thicker oils that have a more honey-like consistency. Thin is good for easier cold weather starting and reducing friction, while thick is better for maintaining film strength and oil pressure at high temperatures and loads.

Most modern motor oils are formulated from various grades of oil so the oil will have the best characteristics of both thick and thin viscosity oils. Multi-viscosity oils flow well at low temperature for easier starting yet retain enough thickness and film strength at high temperature to provide adequate film strength and lubrication.

As a rule, overhead cam engines (OHC) typically require thinner oils such as 5W-30 or 5W-20 to speed lubrication of the overhead cam(s) and valve-train when the engine is first started.

Most vehicle manufacturers today specify 5W-30 or 10W-30 motor oil for year-round driving. Some also specify 5W-20. Always refer to the vehicle owners' manual for specific oil viscosity recommendations, or markings on the oil filler cap or dipstick.

An SAE viscosity grade is used to specify the viscosity of engine oil. With the PT's double overhead cam (DOHC) engine, only use oils with multiple viscosities such as 5W-30 or 10W-30. These are specified with a dual SAE viscosity grade which indicates the cold-to-hot temperature viscosity range. When possible and appropriate for your area of the country and driving conditions use 5W/30, instead of 10W/30 oil. 5W/30 oil is thinner and will improve your mpg by 1-2%. Look for motor oil that says "Energy Conserving" on the American Petroleum Institute (API) performance symbol to be sure it contains friction-reducing additives to reduce internal engine friction.

Synthetic oils are oils that are refined to a much higher degree than ordinary oils and generally have greater viscosity stability, lower pour points and can withstand higher operating temperatures. Synthetic oils are advertised to improve cold starting, reduce friction, reduce oil consumption and improve fuel economy and performance, but they typically cost about three times as much as regular motor oil. They are especially good for turbocharged and high output engines, but are not recommended for breaking-in newly rebuilt engines. For maximum protection users should stick to their normal oil and filter change service intervals when using synthetic oils. A number of PT owners report using synthetic oils in their Cruisers and their comments are very favorable towards these products.

Review the oil and filter replacement guide for additional information. The guide also includes a list of recommended aftermarket oil filters and procedure tips.

Pit Area Resources

Oil & Filter Guide
Oil Pan Guide

 

Tire Pressure, Balancing and Alignment

According the USDE, every pound per square inch (psi) of under-inflation on all vehicles in the U.S. wastes nearly 4 million gallons of gasoline a year. Under inflated tires increase road-resistance, which can reduce mpg by 5% for every 8 pounds a tire, is under inflated. For every 10% that a tire is deflated tire wear increases 10%.

Underinflation also makes a tire run hot. Increased flexing of the sidewall increases the temperature of the tire, which in turn increases the risk of a tire failure and blowout. They also break traction more easily than one which is properly inflated, which can cause skidding during braking or hard cornering, or wheel spin when accelerating.

When inflating a warm tire add about 4-5psi to the recommended tire pressure and verify the pressure when the tire is cold. When checking a cold tire, follow the recommended tire pressure posted on the Tire Inflation Pressure Label provided with the vehicle (usually on the rear face jamb of the driver's door). Cold inflation pressure is obtained after the vehicle has not been operated for at least 3 hours, or the vehicle is driven less than one mile after being inoperative for 3 hours. Weather conditions also affect air pressure in a tire; it increases in warm weather and decreases in cold weather, 1-2 pounds for every 10 degrees of temperature change.

The domestic PT Cruiser utilizes 34psi per OE tire and the GT (Turbo) 38psi per OE tire. A quality air pressure gauge is recommended to check tire air pressure. Tire pressure should be checked cold once per month and more frequently when the weather temperature varies widely. After checking the air pressure, replace valve cap finger tight.

Have your tires properly balanced and keep the vehicle "in alignment" to obtain the best mpg. As tires roll a certain amount of drag occurs. Due to alignment geometry, a front wheel drive vehicle's (PT) tires tend to move in an inward fashion as the vehicle moves forward. As the tires move in this inward fashion, tires experience greater amounts of drag and resistance, which accelerate tire wear and decrease mpg. If the wheels are as little as a 1/4" out of alignment, mpg is further reduced by another 2%. To counteract these effects, alignment geometry is statically adjusted toe-in or toe-out so that the vehicles tires roll in a straight, non-scuffing, and least resistant manner. If a tire is unbalanced, the unbalanced dynamic forces cause the tire to run eccentrically. This eccentric movement causes reduced tire traction. The loss of traction results in a power loss, thus mpg is reduced. Additionally, unbalanced tires accelerate tire wear.

Driving with the parking brake not fully released can cost a mile or two per gallon on a car that normally delivers 20 miles per gallon.

Review the guides below for additional information.

Pit Area Resources

Tire System Guide
Tire & Wheel Diagnostic
Tire-Pull Diagnostic
General Tire Information
Top 10 Issues List

 

Transaxle – Auomatic & Manual

The transmission is probably the most neglected component on vehicles today, which is surprising given the cost for repair or replacement.

Heat is the number one cause of failures in transmissions. The transmission oil is critical for lubricating the transmission and reducing friction. When the fluid breaks down and loses its viscosity, it no longer effectively lubricates the transmission. This causes premature and excessive wear and results in transmission failure.

Transmission fluid is designed to last many thousands of miles under normal conditions. However, one of the most important factors affecting the life of the fluid and the transmission is the temperature of the fluid. Overheated fluid forms sludge and particles of carbon that can block the minute passages and lines that circulate the fluid throughout the transmission. This causes the transmission to overheat even more and will lead to eventual failure of the transmission.

Some cars come from the factory with coolers that help with the temperature. The transmission oil flows through the cooler as air flows across the cooler to lower the temperature of the transmission fluid. The PT's automatic transmission oil cooler consists of an internal oil-to-coolant type, mounted in the radiator lower tank, and an external air-to-oil type, mounted in front of the radiator. Rubber hoses connect the oil coolers to the automatic transmission.



Anything that puts a load on the engine can cause the transmission to heat up and speed the deterioration of the fluid. Towing a trailer, idling in traffic and climbing long hills is all hard on a transmission. The graph illustrates just how much transmission temperature affects the life of transmission components. Fluid that lasts 50,000 miles at a temperature of 220°F, will only last half that long if the temperature is consistently 20° higher.

Maintenance schedule B recommends changing the automatic transaxle fluid/filter each 48,000 miles, and manual transmission fluid at the same intervals. Under maintenance schedule A there is no maintenance recommended for either transaxle. We agree with other transmission experts who recommend changing the fluid and filter every two to three years or 30,000 miles, or once a year or every 15,000 miles if a vehicle is used for towing or other severe service use.

Transaxle Fluid & Filter Service Maintenance Schedule
Our Schedule	Interval/Mileage
All Engines - Normal Service	Every 2-3 years or 30,000 miles.
All Engines - Heavy Service *	Once a year or every 15,000 miles.
* Used for towing or other severe service use.

Check the transmission fluid level and condition every 6,000 miles or 6 months, which ever interval arrives first. Under extreme usage, or if a problem exists, the fluid should be checked at shorter intervals



On the manual transaxle PT check the fluid level by removing the fill plug. The fluid level should be between the bottom of the fill hole and a point not more than 3/16" below the bottom of the hole. Add fluid, if necessary, to maintain the proper level.

To properly check the automatic transaxle fluid level on the PT the following procedure must be used:

1. The vehicle must be on a level surface.



2. Start the engine and curb idle for a minimum of 60 seconds.



3. Fully apply parking brake.



4. Place the gear selector momentarily in each gear position ending with the lever in (P) Park.



5. Remove the dipstick and determine if the fluid is hot or warm. Hot fluid is approximately 180F which is the normal operating temperature after the vehicle has been driven for 15 miles. The fluid can not be comfortably held between the fingertips. Warm is when the fluid is between 85-125F.



6. Wipe the dipstick clean and reinsert until seated. Remove the dipstick again and note the reading.

A. If the fluid is hot, the reading should be in the cross hatched area market HOT between the upper two holes in the dipstick.

B. If the fluid is warm, the fluid level should be between the lower two holes, into the area marked WARM.

C. If the fluid level shows low, add sufficient transmission fluid to bring to the proper level. Do not overfill.

Low fluid is the primary cause of transmission problems.  On the automatic transaxle operation with an improper fluid level (too much or too little) will greatly reduce the life of the transaxle and of the fluid. If the fluid level is consistently low, suspect a leak. One way to locate a leak is to slip a piece of clean newspaper under the vehicle overnight, but this is not always an accurate indication, since some leaks will occur only when the transmission is operating.

Other leaks can be located by driving the vehicle. Wipe the underside of the transmission clean and drive the vehicle for several miles to bring the fluid temperature to normal. Stop the vehicle, shut off the engine and look for leakage. Keep in mind that the source of the leak may or may not be where the fluid is located. Airflow around the transmission while the vehicle is moving may carry the fluid to some other point.

When adding or replacing fluid it is critical to the performance of transaxle that you use the correct type. Only transmission fluid of the type labeled Mopar ATF+4 (Automatic Transmission Fluid–Type 9602) should be used in the 41TE automatic transaxle and G288 (GT Turbo) manual transaxle. Use of improper or substitute fluids can cause shift problems, torque converter shudder and/or transaxle failure.

Two types of fluid are available in T350 manual transaxle equipped PT models, dependent upon where the vehicle was manufactured. Always add or replace fluid removed or lost with the fluid the transaxle was originally built with (Mopar Transaxle Lubricant Type MS 9417 or ATF+4 Automatic Transmission Fluid Type 9602). Do not mix fluid types. Use of improper or substitute fluids can cause shift problems, torque converter shudder and/or transaxle failure.

Along with fluid level, it is important to check the condition of the fluid. Mopar ATF+4 (Automatic Transmission Fluid) when new is red in color. The ATF is dyed red so it can be identified from other fluids used in the vehicle such as engine oil or antifreeze. The red color is not permanent and is not an indicator of fluid condition. As the vehicle is driven, the ATF will begin to look darker in color and may eventually become brown, which is normal. ATF+4 has a unique odor that may change with age. Consequently, odor and color cannot be used to indicate the fluid condition or the need for a fluid change. A dark brown / black fluid accompanied by burn odor and or deterioration in shift quality may indicate fluid deterioration. When the fluid smells burned, and is contaminated with metal or friction material particles, a complete transaxle recondition is probably required. The transaxle should be inspected by a qualified technician to locate the cause of the burnt fluid.

Vehicles with a manual transmission are a little more fuel-efficient than vehicles with automatic transmissions. A PT with an automatic transmission will average 5-11% poorer mpg than a PT with a manual transmission that is used correctly. A slipping automatic transmission will loose another mile per gallon

All automatic transmissions use a torque converter to couple the engine and transmission. Torque converters are not 100% efficient. Some energy is lost between the input (the impeller) and the output (the turbine) sections. Internally, torque converters use a one-way clutch device to multiply engine torque at low engine rpm's.

This action aids in an automatic transmission vehicle's acceleration capacity. Once turbine speed is approximately 90% of impeller speed, the one-way clutch race spins on its own axis. At this point, the converter is said to be "coupled hydraulically." Under these conditions, up to 10% of the engine's output power could be lost to the torque converter's internal slippage. This accounts for most of the mpg difference between a standard and automatic transmission vehicle. This energy loss is transmitted to the vehicle's radiator and shed as heat.

Torque converters developed in the mid 70's had a "lockup" feature added to reduce this energy loss and improve mpg. The PT utilizes a lockup Torque Converter Clutch (TCC) which is described as a standard torque converter. The impeller and turbine rotate at about the same speed and the stator is freewheeling, providing no torque multiplication. By applying the turbine's piston to the front cover's friction material, a total converter engagement can be obtained. The result of this engagement is a direct 1:1 mechanical link between the engine and the transmission.  The engagement and disengagement of the TCC are automatic and controlled by the Powertrain Control Module. The engagement cannot be activated in the lower gears because it eliminates the torque multiplication effect of the torque converter necessary for acceleration. Inputs that determine clutch engagement are: coolant temperature, vehicle speed and throttle position. The torque converter clutch is engaged by the clutch solenoid on the valve body.

The PT's TCC clutch will not engage until approximately 35mph and after the shift into third gear. Other factors may prevent a converter from locking up.

Besides the vehicle speed sensor indicator, a converter may not lockup for any of the following reasons:

1. Engine temperature too cold - most converters will not lockup until the coolant reaches about 120°F.



2. Overdrive unit locked out - when an automatic overdrive is "locked-out" the torque converter lockup feature will also be locked out. Overdrive lockout would normally only be used when pulling heavy loads, thus the converter is logically "locked out."



3. Under low engine vacuum, heavy part-throttle acceleration is an additional power demand which could result in the engine lugging. To prevent engine lugging, which could result in serious engine damage, a sensor determines if low manifold vacuum exists.

Typical lockup converters connect these sensors in a series creating a "string" arrangement. That is, if one sensor gives a "no" signal then the converter will not lockup. Therefore, for most converters to lockup, the following must be present:

1. Coolant must be at or above minimum temperature.



2. Transmission selector must be in "O" or "OD" overdrive if an overdrive vehicle.



3. Vehicle must be at or above minimum 35mph lockup speed.



4. Transmission must have shifted into the third gear.

A converter may fail internally, which will reduce mpg and affect vehicle performance. If the one-way torque converter clutch slips, then the vehicle will characteristically have very poor acceleration. Mpg will be significantly reduced since engine torque is not being multiplied during acceleration. A vehicle with a slipping one-way torque converter clutch will experience a 20 to 30% decrease in fuel economy.

A one-way torque converter clutch that does not release is a second type of torque converter failure. Vehicles with a non releasing one way clutch will accelerate normally but at a decreased top speed. The failure results in a 30 to 50% reduction in mpg. Top cruising speeds are lowered to 40 or 50 mph. The transmission may shift normally even when the one-way torque converter clutch slips or fails to release properly!

Lockup torque converters may exhibit additional fuel-eating malfunctions. Sensors for temperature, speed, selector position, and engine vacuum may fail. Internally, the lockup device itself could fail or wear out. Whatever the malfunction, mpg will be decreased.

Technicians usually hear the complaints of "poor performance" and "low mpg" and need to be able to identify a malfunctioning torque converter or a lockup torque converter that fails to lockup.

Review the guides below for additional information.

Pit Area Resources

41TE Automatic Transaxle System Guide
T350 Manual Transaxle Guide
G288 Getrag Manual Transaxle Guide
General Transaxle Diagnostic Guide

 

Fuel Injection System

The PT's 2.4L engine utilizes a sequential Multi-Port Electronic Fuel Injection system. The MPI system is computer regulated and provides precise air/fuel ratios for all driving conditions. MPI systems generally offer smoother performance, more power and improved fuel economy when compared with other fuel injection systems such as TBI (Throttle Body Injection) technology.

Over time, a buildup of fuel deposits can cause partial blockage of the fuel injectors. The injectors need to be cleaned, if an engine is experiencing any of the classic symptoms of dirty injectors, such as lean misfire, rough idle, hesitation and stumbling on light acceleration, a loss of power, poor fuel economy, and higher hydrocarbon and carbon monoxide emissions.

Review the guides below for additional information.

Resource

Fuel Injection System Servicing

 

Gas Saving Devices

We have discussed a number of practical steps each consumer can take to increase their MPG. However, inevitably, as gas prices spike we often see an increase in new “gas saving devices” advertised on the internet and in print magazines. Most of these companies promise to increase our fuel efficiency by simply installing their nominally priced devices on our vehicles. The Federal Trade Commission and other groups have tested many of these devices and warn consumers to be wary of any gas-saving claims for automotive devices or oil and gas additives. Even for the few gas-saving products that have been found to work, the savings have been small.

Review the articles below for additional information on gas saving devices.

Resource

FTC - "Gas-Saving" Products: Fact or Fuelishness?
Consumer Reports - Gas savers: Do they really help?
FTC - Bogus Fuel-Saving Device Sellers Settle FTC Charges
Wikipedia - Fuel Saving Devices
Popular Mechanics - Looking For A Miracle
ABC News - Tips To Save At The Pump ((PDF)
Fuel-Saving Devices Not Worth The Money
ABC News - Can A Pill Reduce Your Gas Costs?
Fuel-Saving Devices Put To The Test