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.
1992 Chevrolet G 30 Van V8-350 5.7LFACTORY OEM SERVICE PROCEDURE
Idle Speed
CONTROLLED IDLE SPEED CHECK
NOTE: Before performing this check, there should be no codes displayed, idle air control system has been checked and the ignition timing is correct.
1. Set parking brake and block drive wheels.
2. Connect a SCAN tool to the assembly line data link (ALDL) connect with tool in Open Mode.
3. START engine and bring it to normal operating temperature.
4. Check for correct state of PARK/NEUTRAL switch on SCAN tool.
5. Check specifications chart for controlled idle speed and IAC valve pintle position (counts).
6. If within specifications, the idle speed is being correctly controlled by the ECM.
7. If not within specifications refer to COMPUTERS AND CONTROLS / SYSTEM DIAGNOSIS / TESTING AND INSPECTION / PROCEDURES / DIAGNOSIS BY SYMPTOM / ROUGH, UNSTABLE OR INCORRECT IDLE, STALLING.
UNDER 8500 GVW
Transmission Gear Idle Speed IAC Counts OPEN/CLOSED Loop
Man N 600 5-30 [1] OL [2]
Auto D 525 5-30 [1] CL [2]
[1] Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level.
[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).
OVER 8500 GVW
Transmission Gear Idle Speed IAC Counts OPEN/CLOSED Loop
Man N 600 5-30 [1] OL [2]
Man [3] N 600 5-30 [1] CL [4] [2]
Auto D 550 5-30 [1] CL [2]
[1] Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level.
[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).
[3] G van and Suburban with a single catalytic converter.
[4] Switches to OPEN LOOP after three minutes.
NOTE: Before performing this check, there should be no codes displayed, idle air control system has been checked and the ignition timing is correct.
1. Set parking brake and block drive wheels.
2. Connect a SCAN tool to the assembly line data link (ALDL) connect with tool in Open Mode.
3. START engine and bring it to normal operating temperature.
4. Check for correct state of PARK/NEUTRAL switch on SCAN tool.
5. Check specifications chart for controlled idle speed and IAC valve pintle position (counts).
6. If within specifications, the idle speed is being correctly controlled by the ECM.
7. If not within specifications refer to COMPUTERS AND CONTROLS / SYSTEM DIAGNOSIS / TESTING AND INSPECTION / PROCEDURES / DIAGNOSIS BY SYMPTOM / ROUGH, UNSTABLE OR INCORRECT IDLE, STALLING.
UNDER 8500 GVW
Transmission Gear Idle Speed IAC Counts OPEN/CLOSED Loop
Man N 600 5-30 [1] OL [2]
Auto D 525 5-30 [1] CL [2]
[1] Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level.
[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).
OVER 8500 GVW
Transmission Gear Idle Speed IAC Counts OPEN/CLOSED Loop
Man N 600 5-30 [1] OL [2]
Man [3] N 600 5-30 [1] CL [4] [2]
Auto D 550 5-30 [1] CL [2]
[1] Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level.
[2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop).
[3] G van and Suburban with a single catalytic converter.
[4] Switches to OPEN LOOP after three minutes.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.