ENGINE STALLS ON COAST DOWN CLEAN CARBON DEPOSITS
SUBJECT: INTERMITTENT STALL; ENGINE STALLING ON COAST DOWN; HESITATION COLD (DIAGNOSIS AND CLEAN CARBON DEPOSITS)
VEHICLES AFFECTED: 1990-92 CADILLAC "C,E,K" MODELS DEVILLE, FLEETWOOD, ELDORADO, SEVILLE
THIS BULLETIN HAS BEEN REVISED TO ADD 1992 MODELS, INCLUDE UPDATED PART NUMBERS AND REPAIR PROCEDURES.
Some owners of 1990-1992 DeVilles, Fleetwoods, Eldorados, and Sevilles may experience an intermittent stall after start cold, stall on coast down with an immediate restart,-or cold engine hesitation. This condition may be accompanied by an ECM code E22, E26, E32, E55, E70, or E85. This may be caused by an erratic signal from the Throttle Position Sensor (TPS), a poor ground connection near the starter, and/or PCM PROM calibration.
To repair this condition use the following procedure:
1. For 1990-1991 vehicles only, visually inspect the TPS. If the TPS is the old style, replace it with P/N 17112609 (Figure 1). Refer to Section 6E-C2 of the appropriate Service Manual for correct replacement and adjustment procedures.
2. Relocate ground connection near starter (Figure 2) as follows (use procedure in Product Service Bulletin 90-645-107 when available):
- On DeVilles and Fleetwoods, remove ground terminal (G101) from front motor mount stud. - on Eldorados and Sevilles, remove ground terminal from starter bracket stud. - Remove starter bracket and bend as necessary to provide clearance between bracket and block for ground terminal. - Clean ground terminal and block with a wire brush. - Install starter bracket with ground terminal between block and bracket. - Torque starter bracket to block 38 N.m (27 lb. ft.) and starter bracket to starter 3.0 N.m (27 lb. in.)
NOTE: Remove all star washers at this ground connection.
3. On 1991 and 1992 vehicles only, check the PCM PROM I.D. using on-board diagnostics. If the PROM I.D. in the vehicle is lower than the indicated service PROM I.D. in the following chart, replace the PROM with the indicated part number.
Service Service Emission PROM Broadcast Service Vehicle Year System I.D. Code P/N ----------------------- -------- -------- ------- --------- -------- DeVille Coupe/Sedan, 1991-1992 Fed. 417 BBXF 16180314 Fleetwood Coupe
DeVille Coupe/Sedan, 1991-1992 Cal. 418 BBXH 16180315 Fleetwood Coupe
Fleetwood Sedan, 1991-1992 Fed. 421 BBXL 16180320 60 Special, Funeral Coach
Fleetwood Sedan, 1991-1992 Cal. 419 BBXJ 16180317 60 Special
C - Touring Sedan 1991-1992 Fed. 416 BBXC 16180312
C - Touring Sedan 1991 Cal. 416 BBXC 16180312
C - Touring Sedan 1992 Cal. 415 BBXB 16180310
C - Heavy Duty 1991-1992 Fed/Cal 420 BBXK 16180318 Chassis E/K 1991 Fed. 1065 BBWW 16180302
E/K 1991 Cal. 1066 BBWX 16180303
E/K 1992 Fed. 1068 BBWZ 16180307
E/K 1992 Cal. 1069 BBXA 16180308
ETC/STS 1991 Fed/Cal 1067 BBWY 16180304
ETC/STS 1992 Fed/Cal 1070 BBXD 16180313
4. Clean carbon deposits from the throttle blades and bores using a soft bristle brush (i.e., toothbrush) and GM top engine cleaner, P/N 993026, or A/C-Delco carburetor tune-up conditioner, P/N X66-P, or equivalent.
IMPORTANT: Do not use any solvent that contains methyl ethyl ketone.
5. Perform TPS and idle learn Procedure:
NOTE: Do not touch the accelerator pedal or steering wheel during the TPS and idle learn procedure. Make sure the outside air temperature reading is at least 10 degrees C (50 degrees F).
- Inspect throttle linkage for any signs of binding or improper cruise control cable adjustment. Ensure the accelerator pedal is free and clear. - Ensure the minimum air rpm is set at 500 rpm on vehicles with less than 800 km (500 miles) or 525 rpm on vehicles with more than 800 km (500 miles). - Turn ignition on, enter diagnostics and wait for code display to begin, turn ignition off, and wait 20 seconds. - Turn ignition on, enter diagnostics and wait for code display to begin, turn ignition off, and wait 20 seconds. - Turn ignition on, enter diagnostics and wait for code display-to begin, turn ignition off, and wait 20 seconds. - On 1990 vehicles, run the engine continuously for 18 minutes (under any operating conditions). - On 1991 and 1992 vehicles, run the engine continuously for 13 minutes (under any operating conditions). - Apply brake and shift transaxle into Drive. - Place the Electronic Climate Control in the OFF position and allow engine to idle for one minute. - Make sure the outside air temperature reading is at least 10 degrees C (50 degrees F). - Place the Electronic Climate Control in the AUTO position, select HIGH blower, verify A/C clutch engagement by listening for A/C clutch "click" under hood, and allow engine to idle for one minute. - Place transaxle in Park and turn ignition off.
IMPORTANT: Because of the load differences on the engine with A/C on versus A/C off, idle learning must be completed under both conditions.
6. If the above steps do not correct the stalling or hesitation problem, continue diagnosis using the appropriate Service Manual procedures.
For vehicles repaired under warranty use:
VEHICLE SERIES
Operation Description C E K
Engine Stalling on Coast 1.0 1.0 1.0 Down and/or ECM Codes E22, E26, E32, E55, E70, or E85
ADD:
A - To replace TPS 0.3 0.3 0.3 B - To replace PROM 0.4 0.4 0.4
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.
