Engine - Misses, Surges, or Backfires in All Modes

91saturn03

NO.: 91-T-22A

DATE: August, 1991

GROUP: Electrical

CORP. NO.: 186402


SUBJECT: Engine Misses, Surges or Backfires (Poor Ground at Electronic Distributorless Ignition (DIS) Module) All 1991 Saturns - VIN No. 104754 and Below


Due to an error in the part number for the Module Asm - Elek Ign, this bulletin supercedes Bulletin No. 91-T-22, which should be discarded.


CONDITION: Engine misses, surges or backfires during all driving conditions.


CAUSE: The electronic distributorless ignition system (DIS) module bolt heads may not be making good contact with the ground straps molded into the coil housing. This may cause micro-arcing between the bolt head and the ground straps molded into the coil housing, causing interference with DIS module operation.


CORRECTIVE
ACTION: Replace DIS module with a new service replacement module. The new replacement module has an internal change to the electronic grounding that protects it from any external micro-arcing that may interfere with the firing signal.


PROCEDURES:

1. Verify the condition. If condition is verified, perform a visual inspection making sure that the spark plug wires are seated properly and that the spark plug wires and the DIS wiring is routed correctly.

2. Torque the four DIS module mounting bolts.

Torque: 7 N-m (61 lbs.in.)

IMPORTANT: The two mounting bolts, closest to the front of the engine, must be properly torqued. These are the two bolts that provide a ground path for the laminated coils.

3.

a. Drive the vehicle under the same conditions that originally caused it to miss, surge or backfire. If the condition has been repaired, replace the DIS module and coils.

NOTE: The micro-arcing will not damage the DIS module, however, the DIS module must be replaced to prevent any future reoccurrence of the condition.

Refer to the "Distributorless Ignition (DIS) Module and Coils" removal and installation procedures in the "Ignition System" section of the "Electronic Engine Controls Service Manual."

b. If the condition is still present, the problem is not due to external ground of the module. Refer to "Ignition System Diagnostics" in the "Ignition System" section of the "Electronic Engine Controls Service Manual."

PARTS
REQUIREMENTS: 21020180 Module Asm - Elek Ign
21020589 Bolt/Screw - Coil & Elek Ign Module


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 Verify Condition, Torque T9539 1.0 hrs
Bolts, Road Test, Remove and
Replace Electronic Ignition
Module and Bolts
. .
. .