Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to 2000 through 2018 GM passenger cars and trucks, gasoline engines only.

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  GM Passenger Cars and Trucks (including LCF MD) 2000 2018 Gasoline Engines Only

• Customers may report rough idle, crank no start, extended crank or engine misfire.

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  Some customers may comment on the following conditions: • Rough idle. • Crank no start. • Extended crank. • Engine misfire.

• One or more of DTCs P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308 may be set.

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  The technician may find one or more of the following DTCs set: • P0300 • P0301 • P0302 • P0303 • P0304 • P0305 • P0306 • P0307 • P0308

Possible causes

• The cause may be major carbon build up on the intake and/or exhaust valves from fuel contamination or incomplete burning; misfires should not appear before at least 5,000 miles (= 8,047 km) (8,000 kilometers).

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  This condition may be caused by major carbon build up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel as shown below so the misfires should not have appeared until accumulating at least 5,000 miles (8,000 kilometers) or more.

Steps to confirm (in the document’s order)

• With the engine cold, compression on multiple cylinders may be at 0 PSI (= 0 kPa).

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

Repair

1. If there is no valve damage and no cam followers out of place, perform the cleaning procedure to free sticking valves and remove carbon from valves and pistons.

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   If there is no sign of valve damage or cam followers that are out of place, perform the following procedure to free up sticking valves and to remove carbon from the valves and pistons.

2. If valve damage is present or cam followers are out of place, make the mechanical repairs first, then perform the cleaning procedure to prevent recurrence.

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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.

3. Fill Cleaner Kit J-35800-A with about 16 oz. (473 ml) of Top Engine Cleaner, close the cap tightly and set the air pressure to 40 psi (260 kPa) at the tool.

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   Fill Cleaner Kit J-35800-A with Top Engine Cleaner approx. 16 oz. (473 ml) and close cap of tool tightly. Set the air pressure to 40 psi (260 kPa) at the service tool.

4. Using GDS 2, command engine idle to 2000 rpm to prevent stalling.

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   Using GDS 2 command engine idle to 2000 rpm to prevent the engine from stalling.

5. With the engine at operating temperature in a well-ventilated area, slowly and carefully induce the Top Engine Cleaner; it should take approximately 3 minutes.

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   In a well-ventilated area with the engine at operating temperature, slowly/carefully induce the Top Engine Cleaner into the engine which should take approximately 3 minutes.

Parts

• ACDelco Top Engine Cleaner, P/N 19355198 (in Canada P/N 19355199), quantity 1.

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  ACDelco Top Engine Cleaner 19355198 (In Canada, use P/N 19355199)

Caution

• Inducing too much cleaner at too low an RPM, or stalling the engine with too much cleaner at once, 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).