Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to GM passenger cars and trucks, 2000 through 2020, gasoline engines only.

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

• 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 through 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; 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 be zero; the engine may pop through the intake or exhaust while cranking and the spark plugs may be fuel-fouled.

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  When the engine is cold, the compression on multiple cylinders may be at 0 kPa (0 psi). 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 no valve damage and no cam follower out of place, perform the procedure to free up 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 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 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, slowly induce the cleaner into the engine over about 3 minutes, preferably through the throttle body.

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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. ⇒For best results, it is suggested to induce the cleaner through the throttle body with Fuel Injector Cleaner Kit J-35800-A or equivalent and NEW Cleaner Nozzle EN-35800-20, which has been developed to help atomize the cleaner.

5. Afterwards change the engine oil and filter.

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   5. Change the engine oil and filter, and advise the customer to only use one of the Top Tier Gasoline locations listed at http://www.toptiergas.com and/or in the latest version of Service Bulletin 05-06-04-022 to minimize future deposits.

Parts

• ACDelco Top Engine Cleaner: 19355198 (U.S.), 19355199 (Canada), 19368261 (Mexico).

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  ACDelco Top Engine Cleaner 19355198 (U.S.) 1 19355199 (Canada) 19368261 (Mexico)

Caution

• Do not hydro-lock the engine: inducing too much cleaner at too low an RPM, or stalling the engine with it, may bend a connecting rod.

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  If too much cleaner is induced at too low of an 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).