Carbon buildup on the top of the piston is common. Over time this can lead to symptoms varying from light ticking to knocking noises. Performing a fuel injector cleaning procedure can often help the condition by removing some of the piston top deposits.
Car problem reports
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Newest reported 1991 Dodge Shadow problems
The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.
A noise from the rear suspension may be noted at slow speeds over uneven road surfaces. This can be caused by a cracked or broken rear torsion bar. A damaged torsion bar will require replacement.
4 cylinder engines may develop a coolant leak from the water pump area. It is not uncommon for the sealant used on the water pump to degrade over time, newer models have an upgraded rubber gasket. Our technicians tell us that the o-ring where the water pump housing mounts to the engine block may also leak which can appear to be a leaking water pump.
Vehicles may develop a start and die out condition or a transmission that defaults to second gear. Our technicians tell us that the transmission control module (TCM) may be at fault and require replacement. If the TCM is replaced the pinion factor should be reset and the quick learn procedure performed.
Erratic operation of the heater may be caused by a leaking head gasket. Our technicians recommend a complete inspection of the cooling system and engine should be performed if this condition is present.
Alternator pulley misalignment on 4 cylinder engines may result in belt noise and/or the belt "walking" partially off the pulley. Our technicians tell us that replacement of the AC and alternator mounting bracket, alternator belt, and if necessary, installation of washers to align the alternator pulley may be necessary to correct this issue.
Vehicles equipped with a 4 cylinder engine may develop a no start or stalling condition, most commonly caused by a failed distributor pickup plate.
Erratic operation of the speedometer may be noted on vehicles equipped with a passenger side motorized seat belt. This is generally caused by a failed Passive Belt Control Module (PBCM). Our technicians tell us that if the speedometer functions correctly with the PBCM disconnected the PBCM should be replaced.
4 Cylinder engines may exhibit an erratic idle with the Check Engine Light illuminated. These conditions are most commonly present during cold engine operation in rainy weather. Our technicians tells us that there is an updated idle air control valve available to correct this concern.
4 cylinder engines may develop driveability issues and illuminate the Check Engine Light due to engine vacuum leaks. These vehicles use plastic vacuum lines which can become brittle due to heat and age. Care should be taken when replacing these lines as some may have a restrictor orifice molded inside. If lines are replaced without including the restrictors driveability issues will remain.