Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to all 2000-2015 light duty trucks with gasoline engines.

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  2000-2015 All Light Duty Trucks with Gasoline Engines

• Customers may complain of a MIL and/or engine misfire, rough idle, extended crank, or crank no start.

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  Some customers may complain of a MIL and/ or engine misfire, rough idle, extended crank, or crank no start

• One or more misfire codes (DTC P0300-P0308) are found stored in the ECM.

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  the technician will find one or more misfire codes (DTC P0300-P0308) stored in the ECM

Possible causes

• The condition may result from major carbon build up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel.

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  This may be the result of major carbon build up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel

Steps to confirm (in the document’s order)

1. With the engine cold, compression on multiple cylinders may read 0 PSI (= 0 kPa).

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   When the engine is cold, the compression on multiple cylinders may be at 0 PSI.

2. The engine may pop through the intake or exhaust while cranking, and the spark plugs may be fuel fouled.

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   The engine also may pop through the intake or exhaust while cranking and the spark plugs may be fuel fouled when inspected.

Repair

1. If there is valve damage or cam followers are out of place, make the mechanical repairs first, then perform the cleaning procedure to keep the concern from returning.

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   If valve damage is present or if there are cam followers that are out of place, perform engine mechanical repairs as necessary to correct the concern and then perform the procedure below to prevent the concern from returning.

2. With the engine at operating temperature, slowly induce a bottle of GM Upper Engine and Fuel Injection Cleaner with RPM held above idle so the engine does not stall (typically around 2,000 RPM).

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   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 th engine with RPM off of idle enough to prevent the engine from stalling (typically around 2,000 RPM or so).

3. Turn the engine off and let the cleaner soak for 2.5 to 3 hours.

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   Turn the engine off after inducing the cleaner and allow the cleaner to soak with the engine off for 2.5 to 3 hours

4. To complete the repair, change the engine oil and filter.

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   To complete the repairs, change the engine oil and filter

Parts

• Upper Engine and Fuel Injector Cleaner is P/N 88861803 (in Canada, P/N 88861804).

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  88861803 (In Canada, use P/N 88861804) Upper Engine and Fuel Injector Cleaner

Caution

• Inducing too much cleaner at too low an RPM, or stalling the engine with cleaner, may hydro-lock the engine and bend a connecting rod.

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  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 hydro-lock and bend a connecting rod(s).