dieselmech0331
Registered Member
Was running fine now idles aroumd 2000 rpm and will not idle back. Wat could be the problem?
CK5
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89 tbi extremely high idle help
- Thread starter dieselmech0331
- Start date
Vacuum leak!
stuck IAC... make sure to check your codes...
Worn out throttle shaft bushings can do this too. They get misaligned and won't let the blades close all the way. That's how my 87 was when I got it, PO tried to fix it by adding throttle return springs. All that accomplished was making a hard pedal. 
my last tbi sucked in part of the brittle tbi gasket.
One truck my friend had in his shop for a "too high an idle speed" problem turned out to be the PCV valve was some cheapo brand plastic POS that had melted somewhat,and the little disc thing in it couldn't move freely,so it allowed a vacuum leak constantly,instead of the spring in it letting the disc close off the vacuum like it should..
The thing didn't always idle too high ,so it made it harder to diagnose..truck threw no codes, and he tried swapping a good used IAC motor on it and cleaning the throttle body to no avail,before he found the PCV valve was faulty...put a new one with a metal body on it and the idle speed returned to normal after a few minutes of running it..
The thing didn't always idle too high ,so it made it harder to diagnose..truck threw no codes, and he tried swapping a good used IAC motor on it and cleaning the throttle body to no avail,before he found the PCV valve was faulty...put a new one with a metal body on it and the idle speed returned to normal after a few minutes of running it..
