When I let off the gas, or brake, the rpms drop to 500 or below, and usualy kills the car. Whats going on? Any ideas why this is happening?

BlackBowTie

 

You could have a bad or sticking IAC motor. Its the thing on the bottom of the throttle body. Follow the procedure in the tech article on resetting it. If it keeps hapenning, its either a bad IAC, or its not the IAC at all.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

GM has service procedure designed to eliminate this problem. Some TPI cars had the minimium idle speed set too low from the factory. If the minimium idle speed was too low the car would stall at the first stop after an extended cruising period. It appears that the IAC could not react fast enough to correct the low idle and the car would die. After restarting the car it would idle fine. If this is your problem, I would reset your minimium idle speed to 450 - 500 RPM in drive. This will prevent the car from stalling due to minimium idle speed being set too low.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

 

Well then, lemme ask ya'll this. My computer doesn't have the diagnostic link. Its either cramed way up under the dash, or just isn't there anymore. Its an 83 car w/ an 90 interior, 84 block, 89 TPI system/computer w/ a piggyback style control system that makes changes to WOT and idle speed from the cocpit. So...how to aproach this problem is the main key
I call it a bastard car, and for good reason huh?


It just started doing this too, after I got my tranny rebuilt (horrible story). The MAP sensor is like almost dead, it will crank then shut of imediatly, then crank for ~7 seconds then fire up (but flooded, so puffs out lots of black) and the MAP light on the digital fuel system peice keeps lighting up. I will try to clean the IAC, but dunno how to reset it w/o the use of the computer....



Thanks


BLack Bow Tie