ENGINE STUMBLES RUNS ROUGH OR SURGES DURING START. Saturn Saturn 1994

For 1990-2009 cars

# ENGINE STUMBLES RUNS ROUGH OR SURGES DURING START

#### SUBJECT: Engine Stumbles, Runs Rough or Surges During Initial Start-SOHC (LKO) and DOHC (LLO) Engines (Clean Carbon Deposits From Intake Valves)

#### MODELS AFFECTED: 1991-1994 Saturns

CONDITION: Some customers may comment that the vehicle may stumble, run rough or surge on initial cold start.

CAUSE: The intake valves may accumulate carbon or fuel deposits due to driving schedules and/or using gasoline without proper fuel additives.

#### IMPORTANT: Carbon deposits from oil can usually be removed with Saturn Top Engine Cleaner (P/N 21007128) or equivalent, using the procedure outlined in this bulletin. Fuel deposits most frequently occur on SOHC (LKO) engine intake valves and must be removed with Saturn Carbon Blaster SA9212NE (or equivalent carbon blaster tool). Chemical cleaners will not remove fuel deposits.

CORRECTION: Perform the following procedures to remove carbon and fuel deposit accumulation.

PROCEDURE: SOHC (LKO) ENGINES ----------------------------- IMPORTANT: Prior to performing the following procedures on 1991 - 1992 vehicles built before and including VIN NZ241997, refer to "Technical Information Bulletin 92 - T - 14A - Oil Consumption on DOHC Engines or Carbon Buildup On SOHC Engines (Replace Valve Stem Seals)" and follow the procedures listed in the bulletin.

Chemical Valve Cleaning - SOHC (LKO) Engine

1. Run engine until normal operating temperature is obtained.

2. Turn ignition Off.

3. Disable electronic ignition system by removing "DIS" fuse and remove air cleaner cover.

4. Remove valve rocker arm cover and loosen intake valve rocker arm shaft to allow the intake valves to close.

5. Pour half the contents of Saturn Top Engine Cleaner (P/N 21007128) or equivalent into the throttle body fuel injector assembly and let soak a minimum of four hours.

#### NOTICE: Spark plugs must be removed to prevent engine damage during cranking.

6. Remove spark plugs and place rags in front of each spark plug hole.

#### NOTICE: Rocker arm tangs (slots) must be properly seated prior to tightening rocker arm shaft bolts or valve and piston damage will occur.

7. Uniformly tighten intake valve rocker arm shaft and install valve rocker arm cover.

Torque: 25 N-m (19 lbs. ft.) - Rocker Arm Shaft 30 N-m (22 lbs. ft.) - Rocker Arm Cover NOTICE: Do not crank engine for longer then 15 seconds at one time or damage to the starter motor could result.

8. Crank engine 15 seconds, wait one minute, than crank engine for another 15 seconds.

9. Remove rags, and install spark plugs and "DIS" fuse.

Torque: 27 N-m (20 lbs. ft.)

10. Start engine and allow it to reach normal operating temperature.

11. Connect PDT to vehicle and perform special test "MAX IAC. "Slowly pour remaining contents of the Saturn Top Engine Cleaner (P/N 21007128) or equivalent into the throttle body fuel injector assembly.

12. Install air cleaner cover.

If the condition still exists, the valves are most likely contaminated with fuel deposits and must be cleaned with the Saturn Carbon Blaster SA9212NE or an equivalent carbon blasting tool. For instructions, refer to "Engine Mechanical Service Manual."

#### DOHC (LLO) ENGINES

Only oil carbon deposits have been identified on the DOHC (LLO) engine valves and the following procedure must be used.

#### IMPORTANT: Prior to performing the following procedure on 1991-1992 vehicles built before and including VIN NZ237382, refer to "Technical Information Bulletin 92-T-14A - Oil Consumption on DOHC Engines or Carbon Buildup On SOHC Engines (Replace Valve Stem Seals)" and follow the procedures listed in the bulletin.

1. Remove front air inlet duct assembly.

2. Run engine until normal operating temperature is obtained.

3. While engine is running, remove positive crankcase ventilation (PCV) valve (also called the crankcase vent valve assembly) from grommet in camshaft cover assembly. Leave PCV valve attached to the vacuum line.

4. Connect PDT to vehicle and perform special test "MAX IAC." Allow complete can of Saturn Top Engine Cleaner (P/N 21007128) or equivalent, to be slowly drawn into the engine through the PCV valve by dipping the PCV valve in and out of the Saturn top engine cleaner.

5. Install front air inlet duct assembly and the PCV valve into the grommet in the camshaft cover assembly

Verify that the condition has been repaired. If the condition still exists, refer to the appropriate service manual for diagnostic procedures.

PARTS REQUIREMENTS: 21007128 Saturn Top Engine Cleaner

CLAIM INFORMATION: To receive credit for this repair, submit a claim through the Saturn Dealer System as follows: Labor Case Operation Type Description Code Time ---------------------------------------------------------- VW Chemical Valve T9659 1.3 hrs Cleaning-SOHC Engine

VW Chemical Valve T9659 0.8 hrs Cleaning-DOHC Engine

Add if required: VW Clean (Carbon Blaster) Valves, J0400 3.4 hrs Intake - SOHC Engine

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those 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 a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.