ENG STALL/HESIT DURING OPEN TO CLOSE LOOP TRANS AT COLD TEMP.. Saturn Saturn 1991

For 1990-2009 cars

# ENG STALL/HESIT DURING OPEN TO CLOSE LOOP TRANS AT COLD TEMP.

#### SUBJECT: SOHC (LKO) Engine Stalls or Hesitates During Open to Closed Loop Transition at Cold Temperatures (Install New PCM and Camshaft)

#### MODELS AFFECTED: All 1991 Saturns equipped with SOHC (LKO) engines

CONDITION: Some owners of 1991 Saturns with the SOHC (LKO) engine may comment that the engine stalls or hesitates during cold temperature warm-up or after about one minute of operation.

CAUSE: Due to the new federal regulations to address spring and summer Reid Vapor Pressure (RVP) of fuel, warm-up driveability has been impacted.

CORRECTIVE ACTION: Verify stall or hesitation condition during engine warm-up, about one minute after start or just after open to closed loop transition. If condition is verified, proceed with the following steps.

1. Use the scan tool to check for PCM EC/TC codes and flags. If codes or flags are present, refer to the appropriate chart in the "Electronic Engine Controls" or "Automatic Transaxle" service manuals and repair the concern.

If no codes or flags are present, monitor scan tool data and verify all parameters are within specification. Refer to the "Scan Tool General Information Table" in the "Electronic Engine Controls Service Manual."

2. If no codes or flags are present and the scan tool data is within specification, install a new camshaft, powertrain control module (PCM) and calibration. For camshaft replacement, refer to "Camshaft Removal - In-Vehicle" in the "SOHC (LKO) Cylinder Head" section of the "Engine-Mechanical Service Manual."

#### IMPORTANT: Before replacing camshaft, you must verify that it has not already been replaced. To see which camshaft is installed, refer to the "Vehicle History" to see if the camshaft was replaced with P/N 21006395, or inspect the end of the camshaft. If the number stamped on the end of the camshaft is 21000980, the camshaft must be replaced. (This number is on the opposite end of the camshaft gear.)

For PCM replacement, refer to "Powertrain Control Module" in the "Electronic Engine Controls Service Manual."

#### IMPORTANT: Both the camshaft and PCM must be replaced. Also, before installing the calibration, make a note of the transaxle calibration installed, and download the same transaxle calibration with the correct engine calibration.

1991 CALIBRATIONS SOHC (LKO) ENGINES

1438 Manual Transaxles 1442 Automatic Transaxle "Trans Idler" calibration 1440 Automatic Transaxle

#### IMPORTANT: After repair, verify vehicle does not stall or hesitate during the warm-up period. If vehicle still stalls or hesitates during warm-up period, refer to the "Electronic Engine Controls Service Manual" for the correct diagnostic procedures.

PARTS REQUIREMENTS: 21022373 Powertrain Control Module-SOHC (LKO) Manual 21022374 Powertrain Control Module-SOHC (LKO) Auto 21006395 Camshaft

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 PCM EC/TC Calibration T9635 0.5 hrs (Includes PDT [Scan Tool] Parameter and Code/Flag Checks) and Install New PCM ADD: A - Remove and Install 4.5 hrs Camshaft B - With Power Steering 0.3 hrs C - Replace Rocker 0.3 hrs Gasket if Necessary

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.