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Idle Speed & Mixture

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.
CONTROLLED IDLE SPEED & IAC COUNT

Application Idle RPM (1) IAC Counts
4.3L TBI
"G" Series
Auto. Trans. (2) 538 5-30
Man. Trans. (3) 650 5-30
"P" Series
Auto. Trans. (2) 650 20-35
5.7L TBI
"P" Series
Under 8500 GVW
Auto. Trans. (2) 550 5-30
Man. Trans. (3) 660 5-30
Over 8500 GVW
Auto. Trans. (2) 550 5-30
Man. Trans. (3) 600 5-30
7.4L TBI
"G" & "P" Series
Auto. Trans. (2) 750 5-30
Man. Trans. (3) 800 5-30
(1) Add 2 counts for engines with less than 500 miles. On 4.3L and V8 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.
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