Note. Idle mixture on fuel injected models is controlled by Electronic Control Module (ECM) and is not adjustable. Controlled idle speed and IAC count can be checked using scan tester. See CONTROLLED IDLE SPEED & IAC COUNT table.
| Application | Idle RPM | (1) IAC Counts |
|---|
| 4.3L CPI |
| "L" Series |
| Auto. Trans. (2) | 625 | 15-50 |
| "M", "S" & "T" Series |
| Auto. Trans. (2) | 550 | 5-40 |
| 4.3L TBI |
| "C" & "K" Series |
| Auto. Trans. (2) (4) | 537 | 5-30 |
| Auto. Trans. (2) (4) | 650 | 20-35 |
| Manual Trans. (3) | 550 | 2-20 |
| "G" Series |
| Auto. Trans. (2) | 538 | 5-30 |
| Manual Trans. (3) | 650 | 5-30 |
| "L" Series |
| Auto. Trans. (2) | 625 | 5-50 |
| Manual Trans. (3) | 700 | 3-30 |
| "M" Series |
| Auto. Trans. (2) | 538 | 5-30 |
| "P" Series |
| Auto. Trans. (2) | 650 | 5-30 |
| Manual Trans. (2) | 700 | 5-30 |
| "S" & "T" Series |
| Auto. Trans. (2) | 650 | 5-30 |
| Manual Trans. |
| Pickup | 725 | 3-30 |
| Utility | 700 | 5-30 |
| (1) Add 2 counts for engines with less than 500 miles. On 4.3L engines, add 2 counts for every 1000 ft. above sea level. (2) Automatic transmission in Drive. (3) Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. (4) Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. |
| (1) | Add 2 counts for engines with less than 500 miles. On 4.3L engines, add 2 counts for every 1000 ft. above sea level. |
| (2) | Automatic transmission in Drive. |
| (3) | Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. |
| (4) | Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. |
CONTROLLED IDLE SPEED & IAC COUNT
