PIP5029: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves - (May 29, 2012) Subject: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves Models:
2008 - 2012 Cadillac CTS, STS 2008 - 2010 Chevrolet Cobalt SS, HHR SS 2007 - 2010 Pontiac Solstice GXP 2007 - 2010 Saturn Sky Redline 2009 - 2012 Buick Enclave 2009 - 2012 Buick Lacrosse 2009 - 2012
Chevrolet Traverse 2009 - 2012
GMC Acadia 2009 Saturn Outlook 2010 - 2012 Cadillac SRX 2010 - 2012 Chevrolet Camaro, Equinox 2010 - 2012 GMC Terrain With any of the Following Direct Injected Gasoline Engines: 2.0 (RPO LNF) 2.4L (RPO LAF, LEA, or LUK) 2.8L (RPO LAU) 3.0L (RPO LF1) 3.6L (RPO LFX or LLT) The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern: Some customers may complain of a MIL and engine misfire. In some cases, the misfire may be more apparent on a cold start, may count on a single cylinder or several cylinders, and may or may not be felt by the driver. Upon inspection, the technician will find one or more misfire codes (DTC P0300-P0306) stored in the ECM and SI diagnosis may or may not isolate the cause of the misfire depending on whether the intake/exhaust valves are sticking at the time of the diagnosis. This may be the result of major carbon build up on the intake and/or exhaust valves as shown below so the misfires should not have appeared until the engine has accumulated around 5,000 miles or more.
Recommendation/Instructions: If this concern is encountered, perform SI diagnosis. If SI diagnosis isolates a valve sealing concern and/or eliminates everything else external to the engine, decarbon the engine with Upper Engine and Fuel Injector Cleaner by following the guidelines below:
Important Extreme care must be taken not to hydrolock the engine when inducing the cleaner, especially if it is induced without Kent Moore Tool # J-35800-A. If too much cleaner is induced at too low of a RPM, or if you force the engine to stall by inducing too much cleaner at once, the engine may hydrolock and bend a connecting rod(s).
1. In a well-ventilated area with the engine at operating temperature, slowly/carefully induce a bottle of GM Upper Engine and Fuel Injection Cleaner into the engine with RPM off of idle enough to prevent it from stalling (typically around 2,000 RPM or so). Depending on the engine configuration, induce the cleaner through the throttle body or an engine vacuum hose/pipe. For best results, it is suggested to induce the cleaner with Kent Moore Tool # J-35800-A (shown below).
2. Turn the engine off after inducing the cleaner and allow the cleaner to soak with the engine off for 2.5 to 3 hours (Do not let cleaner soak for more than 3 hours as remaining deposits may start to harden back up again).
3. Add a bottle of GM Fuel System Treatment Plus to the fuel tank and fill the vehicle with one of the Top Tier gasolines listed at http://www.toptiergas.com
and/or in the latest version of 04-06-04-047 (USA) or 05-06-04022 (Canada). See Bulletin 05-00-89-078 for more details on GM Fuel System Treatment Plus.
4. Test drive the vehicle extensively to circulate the GM Fuel System Treatment Plus, which will help to eliminate/reduce any remaining intake valve deposits.
5. Re-evaluate the concern to determine if it is repaired or improved at all. If the concern is improved but not repaired, it may be necessary to perform the above decarboning process a 2nd time.
6. To complete the repairs, advise the customer to only use one of the Top Tier Gasolines listed at http://www.toptiergas.com
and/or in the latest version of 04-06-04-047 (USA) or 05-06-04-022 (Canada) to minimize future deposits. It can also be recommended to add a bottle of GM Fuel System Treatment Plus at every oil change as mentioned in the latest version of 04-06-04-051. Kent Moore Tool # J-35800-A Upper Engine and Fuel Injector Cleaner Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION © 2012 General Motors. All rights reserved.