Ensure idle speed and base ignition timing are set to specification. See IDLE SPEED SPECIFICATIONS and IGNITION TIMING tables. If necessary, see the ADJUSTMENTS article.

IDLE SPEED SPECIFICATIONS ⁽¹⁾

Application

⁽²⁾ Idle RPM

With A/C Off

750-850

With A/C On

⁽³⁾ 950-1050

⁽¹⁾	Transaxle/transmission in Neutral or Park.

⁽²⁾	Idle speed is checked with scan tool and a jumper wire connected between duty check data link connector terminal No. 2 (Blue/Yellow wire), diagnostic request, and terminal No. 3 (TBI) or No. 4 (SFI), (Black wire) ground.

⁽³⁾	Idle speed should be 750-850 RPM in any gear.

IGNITION TIMING ⁽¹⁾

Application

Man. Trans.

Auto. Trans.

SFI

⁽²⁾ 4-6 @ 800

⁽²⁾ 5 @ 800

TBI

⁽³⁾ 7-9 @ 800

⁽¹⁾	See Fig 1 for timing mark location.

⁽²⁾	With jumper wire installed between 6-pin duty check data link connector terminals No. 4 (Black wire) and No. 5 (Blue/Red wire), located between right strut tower and battery.

⁽³⁾	With jumper wire installed between 4-pin duty check data link connector terminals "C" (Black wire) and "D" (Blue/Red wire), located between right strut tower and battery.

Fig 1: Locating Ignition Timing Mark

Courtesy of GENERAL MOTORS CORP.

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.

Safety Warning

Idle Speed & Ignition Timing

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?

Safety Warning

Idle Speed &amp; Ignition Timing

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?

Idle Speed & Ignition Timing