For 1990-2009 cars

# ENGINE ADJUST FOR ALTITUDE GAS ENGINES

GENERAL MOTORS DOES NOT OFFER ALTITUDE EMISSIONS PACKAGES AS AN OPTION FOR THE 1981 MODEL YEAR. INSTEAD, THE ENVIRONMENTAL PROTECTION AGENCY HAS APPROVED CERTAIN ADJUSTMENTS ON 1981 VEHICLES BUILT AND CERTIFIED FOR OPERATION AT LOW ALTITUDES BUT DELIVERED BY DEALERS LOCATED AT ALTITUDES 4,000 FT. OR HIGHER. THE APPROVAL OF THESE ADJUSTMENTS IS STRICTLY LIMITED TO THOSE DEALERSHIPS LOCATED AT ALTITUDES OF 4,000 FEET OR HIGHER. VEHICLE INSPECTION THIS PROCEDURE APPLIES ONLY TO VEHICLES WITH ENGINES PRODUCED BY CHEVROLET DIVISION OF GENERAL MOTORS. THESE ENGINES, IDENTIFIED BY THE EIGHTH DIGIT OF THE VIN, ARE LISTED BELOW: * PASSENGER CAR VIN ENGINE CODES: H, J, K, L, X, Z, 6, AND 9 * LIGHT DUTY TRUCK VIN ENGINE CODES: D, F, H, G, L, M, N, P, T AND W * MEDIUM AND HEAVY DUTY TRUCK VIN ENGINE CODES: A, B, E, S, AND T THE FOLLOWING VEHICLES, AS IDENTIFIED ON THE UNDERHOOD EMISSION CONTROL LABEL, IS EXCLUDED FROM THIS PROGRAM AND IS NOT TO BE ADJUSTED. DIESELS THE ADJUSTMENTS LISTED IN THE PROCEDURE WILL REDUCE CARBON MONOXIDE EMISSIONS AND IMPROVE ENGINE PERFORMANCE ON LOW ALTITUDE MODELS WHEN OPERATED AT HIGH ALTITUDES. ALTITUDE ADJUSTMENT LABEL WHEN LOW ALTITUDE VEHICLES ARE ADJUSTED FOR HIGH ALTITUDE OPERATION, A SUPPLEMENTAL EMISSION CONTROL INFORMATION LABEL MUST BE PLACED NEXT TO THE EXISTING UNDER HOOD EMISSION CONTROL INFORMATION LABEL. WASH OFF THE AREA WITH SOAP AND WATER, DRY THOROUGHLY, AND APPLY THE NEW LABEL P/N 14037799. ORDER LABELS DIRECT FROM HELM INDUSTRIES AS OUTLINED IN GM PARTS CATALOG #88. DEALER AND CUSTOMER INFORMATION DEALERS LOCATED AT 4,000 FOOT ELEVATIONS OR HIGHER, IN COUNTIES DESIGNATED BY EPA AS HIGH ALTITUDE COUNTIES FOR THE 1977 MODEL YEAR SHOULD PERFORM THESE ADJUSTMENTS PRIOR TO DELIVERY OF AFFECTED VEHICLES TO THE CUSTOMER. VEHICLES WHICH WERE DELIVERED IN AUTHORIZED HIGH ALTITUDE AREAS BUT WHICH WERE NOT ADJUSTED PRIOR TO DELIVERY MAY BE ADJUSTED WHEN THE VEHICLE IS IN FOR NORMAL SERVICE. OWNERS OF 1981 LOW ALTITUDE VEHICLES, PURCHASED IN LOW ALTITUDE AREAS, TAKING UP PERMANENT RESIDENCE IN ONE OF THESE HIGH ALTITUDE COUNTIES SHOULD BE ENCOURAGED TO HAVE THESE ADJUSTMENTS PERFORMED WHEN VEHICLES ARE BROUGHT IN FOR SERVICE. AFTER PERFORMING THESE ADJUSTMENTS, DEALERS MUST ADVISE CUSTOMERS THAT , IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW ALTITUDE OPERATION, THE ENGINE MUST BE RE-ADJUSTED TO LOW ALTITUDE SPECIFICATION PER THE CORRECT CHASSIS SERVICE MANUAL AND THE SUPPLEMENTAL LABEL REMOVED. HANDLING OF ALTITUDE ADJUSTMENT EXPENSE PREDELIVERY OR ORIGINAL HIGH ALTITUDE ADJUSTMENT IS TO BE PERFORMED AT CHEVROLET EXPENSE BY SUBMITTING PROPERLY COMPLETED WARRANTY CLAIM USING FOLLOWING SPECIAL LABOR OPERATION: OPERATION NO. T0010 TIME ALLOWANCE .3 HOURS LABOR EXPENSE TO PERFORM HIGH ALTITUDE ADJUSTMENTS ON VEHICLES PURCHASED IN LOW ALTITUDE COUNTIES BY OWNERS, WHO TAKE UP PERMANENT RESIDENCE IN ONE OF THE HIGH ALTITUDE COUNTIES, ARE THE RESPONSIBILITY OF THE OWNER. LABOR EXPENSE TO RETURN A VEHICLE, ADJUSTED FOR HIGH ALTITUDE OPERATION, TO LOW ALTITUDE SPECIFICATIONS ARE ALSO THE OWNER'S RESPONSIBILITY. PROCEDURE TO BE USED FOR ALL INVOLVED 1981 LOW ALTITUDE ENGINES. ADVANCE IGNITION TIMING AS MUCH AS 4F FROM SPECIFICATIONS ON EMISSION CONTROL INFORMATION LABEL AS LONG AS ROAD TEST REVEALS NO AUDIBLE SPARK KNOCK AT HIGH ALTITUDE. ADJUST IDLE SPEED TO SPECIFICATIONS SHOWN ON THE EMISSION CONTROL INFORMATION LABEL. APPLY SUPPLEMENTAL EMISSION CONTROL LABEL P/N 14037799 PER PREVIOUS INSTRUCTIONS.

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.