DIESEL HIGH ALTITUDE ADJUST ASSIST PERF. & REDUCE SMOKE. Chevrolet Chevette 1984

For 1990-2009 cars

# DIESEL HIGH ALTITUDE ADJUST ASSIST PERF. & REDUCE SMOKE

#### Model and Year 1983-84 CHEVETTE 1.8L DIESEL (CODE D) FEDERAL AND CALIFORNIA

This copy cancels and replaces Chevrolet Dealer Service Bulletin 84-166 dated July, 1984 which should be destroyed. Included in the reissue is the Illustration II referred to but omitted.

An altitude emissions option for 1.8L diesel engines is not available in 1983 and 1984. Vehicles certified for operation at low altitudes and delivered by dealers at 4000 feet altitudes or higher should make the following adjustment to assist performance and reduce smoke:

PROCEDURE FOR HIGH ALTITUDE ADJUSTMENT FOR GENERAL MOTORS 1983 CHEVETTE 1.8L DIESEL ENGINE FAMILY D1G1.8D7ZZ90 AND 1984 FAMILIES E1G1.8D7ZZ91 (FEDERAL) AND E1G1.8E7ZZ10 (CALIFORNIA)

1. These revisions are to be performed with engine not running.

2. Remove the full-load adjusting screw lockwire and seal.

3. While holding the adjusting screw to prevent rotation, loosen the lock nut.

4. Rotate the full-load adjusting screw 90 DEG counter-clockwise (refer to Illustration I).

5. Retorque the lock nut (8-12 N.m) while holding the adjusting screw to prevent rotation.

6. Install a new lockwire and seal.

When LOW ALTITUDE vehicles are adjusted for high altitude operation, a SUPPLEMENTAL EMISSION CONTROL INFORMATION LABEL, P/N 14067201, must be installed in a visible location as close to the existing underhood emission label as possible. The existing emission label is located on the underside of the hood in a "cut-out" in the hood insulation material blanket. It will be necessary to cut the hole larger or find another location in the engine compartment. Do not attach the label to the air cleaner. Prior to attaching the label, clean the area with solvent for good adhesion. Fill in the appropriate information (refer to Illustration II).

#### DEALER AND CUSTOMER INFORMATION

Dealers located at 4000 foot elevations or higher, may perform these adjustments prior to delivery of a Light Duty vehicle to the customer, or after delivery upon owner comment of excessive smoke. Owners of 1983 and 1984 vehicles, purchased in low altitude areas, taking up permanent residence in a high altitude area should be encouraged to have these adjustments performed when vehicles are brought in for service.

After performing these adjustments, dealers should advise customers that IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW ALTITUDE OPERATIONS, THE ENGINE SHOULD BE RE-ADJUSTED TO LOW ALTITUDE SPECIFICATION PER THE CORRECT CHASSIS SERVICE MANUAL AND THE SUPPLEMENTAL LABEL REMOVED.

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.