Recall - High Altitude Exhaust Emissions: Overview

Number: 88C32

Section: 6E

Date: Dec. 1993

Subject:
PRODUCT EMISSION CAMPAIGN 88C32 - HIGH ALTITUDE CO EXHAUST EMISSIONS
=== REISSUE ===

Model and Year:
1988 CHEVROLET NOVA WITH 1.6L ENGINE (RPO LC9)

TO: All Chevrolet Dealers

THIS BULLETIN CANCELS AND SUPERSEDES CAMPAIGN EMISSION BULLETIN 88C30 ISSUED OCTOBER, 1992 AND SUPPLEMENT 88C30(a) ISSUED DECEMBER, 1992. THE SERVICE PROCEDURE HAS BEEN REVISED TO PREVENT A DRIVEABILITY CONCERN WHICH COULD OCCUR AS A RESULT OF PERFORMING CAMPAIGN 88C30.

OWNER'S OF ALL INVOLVED VEHICLES (PREVIOUSLY REPAIRED AND UNREPAIRED) WILL BE SENT NEW NOTIFICATION LETTERS INFORMING THEM:

A > TO HAVE THE CAMPAIGN PERFORMED IF THEY HAVE NOT DONE SO; OR

B > TO RETURN TO THEIR DEALER IF THEY HAVE HAD THE ORIGINAL CAMPAIGN ACTION PERFORMED AND ARE EXPERIENCING A DRIVEABILITY CONCERN; OR

C > TO DO NOTHING IF THEY HAVE HAD THE ORIGINAL CAMPAIGN ACTION PERFORMED AND THEIR VEHICLE IS PERFORMING SATISFACTORILY.

THE CLAIM INFORMATION SECTION HAS ALSO BEEN REVISED TO REFLECT THESE CHANGES INCLUDING THE ADDITION OF LABOR OPERATIONS V7414 AND V7415 TO CORRECT DRIVEABILITY CONCERNS FOR VEHICLES WHICH WHERE REPAIRED UNDER CAMPAIGN 88C30.

General Motors has determined that certain 1988 Chevrolet Nova model vehicles with 1.6L (RPO LC9 - VIN CODE "4") engines may exceed high altitude carbon monoxide (CO) Federal Emission Standards. This condition applies to vehicles registered in Colorado, Nevada, New Mexico and Utah (vehicles which have moved to these states from California which are equipped with RPO YF5 do not require this campaign repair).

To correct this condition, vehicles registered in the four affected states will have an improved electronic bleed-air control valve (EBCV) installed and related vacuum hoses replaced with increased diameter vacuum hoses. Additionally, the 6-way vacuum tee will be replaced with two 3-way vacuum tees and a 2nd HAC (High Altitude Compensation) valve will be added.

It has also been determined that some vehicles repaired under the original issue of this campaign may be experiencing hesitation during engine warm-up and manual transmission vehicles may experience a rough idle condition. A procedure is included in this bulletin to correct this driveability condition on these previously repaired vehicles.