1992 Corvette ZR-1: Service Bulletin: Lack of Wide Open Throttle Engine Underpower

Subject: LACK OF WOT-LOW ENGINE POWER REVISED CABLE ADJUSTMENT PROC.
Model and Year: 1992 CORVETTE ZR-1 WITH 5.7L ENGINE AND MANUAL TRANSMISSION
Source: Chevrolet Product Emission Campaign
Bulletin Number: 92-214A-7B - (07/01/1992)

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 92-2l4-7B, DATED JUNE 1992. THE THROTTLE OPENING NOTATION UNDER "CORRECTION" HAS BEEN CORRECTED. ALL COPIES OF 92-2l4-7B SHOULD BE DISCARDED.

CONDITION:

Customers with VIN up to 800227 may comment about lack of wide open throttle or low engine power for their 1992 model year Corvette ZR-1.

CAUSE:

Adjustment procedures revised at assembly plant.

CORRECTION:

BEFORE MAKING ANY ADJUSTMENT, use a Tech 1 with an 88-92 Brake System Cartridge, check throttle angle percentage by depressing the accelerator pedal. When the pedal is fully depressed, throttle opening should be 100 percent. When the accelerator pedal is released, throttle opening should return to 0 percent. If proper results are not obtained, follow the revised ABS/ASR system adjustment procedures below to improve the above conditions:

1. Remove adjuster cam assembly splash cover, foam shield, and cable cam cover.

2. Disconnect cruise control cable from the cruise control servo.

3. Depress reset button on the throttle control cable and fully extend cable sheaths (see figure).

4. Insert a 1/8 inch drill bit into adjuster assembly alignment hole (see figure, item A).

** NOTICE ** Make certain the drill bit does NOT contact the adjuster assembly gear or improper adjustment and throttle relaxer damage could result.

5. Insert a torque wrench with a 1/4 inch drive extension into square hole on the cruise control cam (type 1) or through the cruise control cam into the accelerator cam (type 2) (see figure, item 6).

6. Turn the torque wrench clockwise until obtaining a torque of 4 N.m (35 lbs. in.). During adjustment, several clicks of the adjuster should be heard. If not, repeat step 3.

7. Remove the torque wrench AND drill bit.

** CAUTION ** Failure to remove drill bit may result in loss of engine control.

8. Adjust cruise control cable. Refer to "Cruise Control Servo Linkage Adjustment" in Section 5El.

9. Replace cable cam cover, foam shield, and adjuster cam assembly splash cover.

10. Using a Tech 1 with an 88-92 Brake System Cartridge, check throttle angle percentage by depressing the accelerator pedal. When the pedal is fully depressed, throttle opening should be 100 percent. When the accelerator pedal is released, throttle opening should return to 0 percent. If proper results are not obtained, check cables for kinks or damage, and repeat adjustment procedures.

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.