Min idle spec TBI 7.4L
 

Comes up often enough I figure I'd post this from the 1994 service manual for the 454 7.4L...

Looking at the 1994 service manual for 454 TBI under fuel systems (Section 4-4A) the 'Min idle speed' setting is... (Factory set screw)

For the 7,4L auto trans in Drive (wheels chocked) is 625 (+-25rpm) Closed loop

Controlled Idle Speed is as follows:

454 7.4L in Drive (wheels chocked) 675 (+- 25rpm) IAC count 5-30 (Closed loop) at operating temp 196-222F (add 2 counts for every 1000ft above sea level

The 'controlled idle speed' is obtained by the control module positioning the IAC valve. A high/low coolant temp or AC clutch engagement may signal the control module to change the IAC counts.

IAC counts will be above 60 if idle is too low and zero counts if idle is too high. Things to check if so...

1. Vacuum leak/s

2. System too rich

3. TB obstruction

4. PCV issue

5. AC issue

For manuals here: https://www.gmt400.com/threads/88-98...manuals.43575/