Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1986C 10 P/U 2WD V8-350 5.7LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTTECHNICAL SERVICE BULLETINSBY SYMPTOMHIGH EMISSIONSENGINE - PERFORMANCE ALTITUDE ADJUSTMENTSOVERVIEW
1986 Chevrolet C 10 P/U 2WD V8-350 5.7L
Engine - Performance Altitude Adjustments: Overview
1986 Chevrolet C 10 P/U 2WD V8-350 5.7LSECTION Overview
86chevy10
Number: 86-46
Section: 6E
Date: MAY, 1986
Subject: ALTITUDE ADJUSTMENTS FOR ENGINE PERFORMANCE
Model and Year: 1986 C,K,G,P - 10-30 FEDERAL EMISSION TRUCKS EXCEPT H.D. DIESEL
TO: ALL CHEVROLET DEALERS
This revised Dealer Bulletin cancels and replaces 86-46 dated March, 1986 which should be destroyed. This reissue reflects correct model usage, from all 1986 Trucks to 1986 C,K,G,P - 10-30 Federal Emission Trucks Except H.D. Diesel.
The adjustments specified within this bulletin are intended for vehicles currently in customer use and do not apply to new vehicles in dealer inventory. The adjustments are provided for the purpose of vehicular performance and customer satisfaction of emissions specifications for the involved vehicles.
This bulletin has been divided into two (2) procedures. Procedure I is applicable to Low Altitude (NA5) trucks taking up permanent residence in a high altitude county. Procedure II is applicable to High Altitude (NA6) trucks being used primarily in low altitude counties.
The only exception is the closed loop (Computer Command Control) system which is self compensating for altitude. Applicable engines which require no adjustment are the 2.5L, 2.8L, 4.3L, 5.0L, and 5.7L California, and all engines in Federal "M and S" trucks.
Number: 86-46
Section: 6E
Date: MAY, 1986
Subject: ALTITUDE ADJUSTMENTS FOR ENGINE PERFORMANCE
Model and Year: 1986 C,K,G,P - 10-30 FEDERAL EMISSION TRUCKS EXCEPT H.D. DIESEL
TO: ALL CHEVROLET DEALERS
This revised Dealer Bulletin cancels and replaces 86-46 dated March, 1986 which should be destroyed. This reissue reflects correct model usage, from all 1986 Trucks to 1986 C,K,G,P - 10-30 Federal Emission Trucks Except H.D. Diesel.
The adjustments specified within this bulletin are intended for vehicles currently in customer use and do not apply to new vehicles in dealer inventory. The adjustments are provided for the purpose of vehicular performance and customer satisfaction of emissions specifications for the involved vehicles.
This bulletin has been divided into two (2) procedures. Procedure I is applicable to Low Altitude (NA5) trucks taking up permanent residence in a high altitude county. Procedure II is applicable to High Altitude (NA6) trucks being used primarily in low altitude counties.
The only exception is the closed loop (Computer Command Control) system which is self compensating for altitude. Applicable engines which require no adjustment are the 2.5L, 2.8L, 4.3L, 5.0L, and 5.7L California, and all engines in Federal "M and S" trucks.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.