Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to GM passenger cars and trucks (including LCF MD), model years 2000 to 2020, gasoline engines only.

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  GM Passenger Cars and Trucks (including LCF MD) 2000 2020 Gasoline Engines Only

• Customers may comment on 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 and 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

• Major carbon build-up on the intake and/or exhaust valves from fuel contamination or incomplete burning of the fuel; the misfires should not appear before at least 8,000 km (5,000 mi).

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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 8,000 km (5,000 mi) or more.

Steps to confirm (in the document’s order)

• With the engine cold, compression on multiple cylinders may read 0 kPa (0 psi).

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

Repair

1. If there is no valve damage and no cam follower out of place, perform the procedure to free sticking valves and remove carbon from the 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. Fill Cleaner Kit J-35800-A with about 473 ml (16 oz) of Top Engine Cleaner, close the cap tightly, and set the air pressure at the tool to 260 kPa (40 psi).

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

3. With GDS 2 or a scan tool, command the engine idle to 2000 rpm so the engine does not stall.

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   2. Using GDS 2 or a Scan Tool, command engine idle to 2000 rpm to prevent the engine from stalling.

4. With the engine at operating temperature, induce the Top Engine Cleaner slowly and carefully, taking approximately 3 minutes, in a well-ventilated area.

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   3. 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, part number 19355198 (U.S.).

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  ACDelco Top Engine Cleaner 19355198 (U.S.)

Caution

• SI diagnosis may or may not isolate the cause of the misfire, depending on whether the valves are sticking at the time of diagnosis.

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  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.

• Take extreme care not to hydro-lock the engine when inducing the cleaner, especially without Fuel Injector Cleaner Kit J-35800-A or equivalent.

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  Extreme care must be taken not to hydro-lock the engine when inducing the cleaner, especially if it is induced without Fuel Injector Cleaner Kit J-35800-A or equivalent.