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Jeep/Ram 5.7L Misfire Low Power Condition

Bulletin 4001

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Application

2011-2015 Chrysler/Dodge/Jeep/Ram 5.7L Engine

Overview

Many vehicle owners have complained of engine misfire or rough running conditions with trouble codes for fuel injector circuits or cylinder misfires (P0300-P0308) setting. Attempting to solve the issue by replacing spark plugs, ignition coils and fuel injectors have proven unsuccessful and costly.

Procedure

This issue has become a fairly common problem in the Jeep/Ram vehicle lineup. The issue will begin with trouble codes setting with no engine running complaints but as the problem persists the vehicle operator will begin to feel the results of this problem. In many instances the spark plugs, ignition coils and fuel injectors may have been replaced to solve the trouble code problem, but the root cause may be much more in depth. The engine in these vehicle applications has a special roller lifter design in their valve train which is meant to reduce friction and improve performance and fuel mileage. Engine lubrication is critical to keep the rollers rotating freely, but when that lubrication suffers, and parts begin to break down the real problems begin. With a lack of lubrication, the roller(s) will begin to seize causing a heat related failure of the iron camshaft and roller assembly. The photos included with this bulletin show the severe damage caused by the lack of lubrication.

 

So, the question may be, what caused the lubrication issue to begin with? Although it is possible the camshaft and roller lifters may have a mechanical defect, all aspects of this failure must be investigated by the service technician. Following the vehicle manufactures oil change interval for the operating characteristics and using the factory recommended rated motor oil is critical to obtain an engine long life expectancy. Extending the oil change interval, using the wrong motor oil or a motor oil not rated for the engine application could lead to breakdown of the lubricating feature of the oil which will then lead to oil coking or hardening of the oil. Once the oil begins to coke the rock-hard carbonized oil particles will circulate throughout the engine lubrication system and cause restricted passages further reducing lubrication at all the stress points. It’s not unusual for not only the camshaft and lifters to fail but also the bearings and piston rings.

 

To correctly diagnose this problem a vacuum gauge and cylinder compression gauge will be required. With the engine running a check of engine vacuum is necessary, an unsteady needle, or jumping needle on the gauge would indicate a mechanical valve train problem. Performing a static and dynamic compression test can reveal a mechanical fault on one or several cylinders.

 

For more information contact the GoTech technical services team for assistance.

 

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