Idol Problem

Asked by Mar 04, 2009 at 12:41 PM about the 1994 Chevrolet Blazer

Question type: Maintenance & Repair

I have a 1994 s-10 chevy blazer i changed the throttle positioning valve, map sensor, ignition control module, and O2 sensor. Now every once in awhile the truck will idol up high then back down to normal while driving it. What do i need to fix to get it to stop doing that?

12 Answers

i have a 96 with 196xxx on it, it started doing the same thing yours is but the problem has gotten worse. lately the problem has gotten alot worse. i cant even drive it anymore its so bad. i have checked the maf, egr, tps, looked for vacuum leaks around the intake, suspected the brake booster causing a vacuum leake and nothing fixes the problem, i cant figure it out...

clean the IAC with carb cleaner,is located on TB,1 plug, round part with 2 tourx screws.

i cleaned the whole carb. stilll no change...


vaccuum hoses are ok? that and a bad air filter caused my 80 grand prix to gallop like that.

ya the vacuum hoses seem to be ok. i have also used carb and choke cleaner to check all of the gaskets. i have checked just about every sensor aswell. i am completly lost...

OK but did u take out the IAC and clean it.

of course, at the same time that i cleaned the tb. i have also checked the conections and wiring for the iac and tps. i have checked everything i can think of. however i have a hunch that my cat is clogged and i know i have a bad o2 sensor. i was told that neither of these would cause this problem.


You might want to pull off the top of the intake manifold and look at your fuel regulator to the injectors. These have a bad habit of leaking fuel directly into the intake and would cause this issue.

if u think you have a bad cat,do the drill test,drill a 1/8 hole in.pipe before cat,best place is past where the 2 down pipes are welded together,crank and drive a few miles,see how it does,if no change doubt the cat is bad,for the hole udrilled,just put a screw in it or have it spot weilded,most exhaust shops will do this test for free.

man that is one of the things i didnt wanna hear but have been fearing... i am having surgury on tuesday so i will take a look at it asap and get back on and report the findings

does anyone on here live somewhere around chesterfield michigan? i need a fuel pressure gauge to diagnose the pressure regulator and i have no wiggle room in my budget to buy or rent one and dont know anyone that owns one. any help would be appreciated


another more efficient way to check catalytic converter operation use a pyrometer and take a reading before and after the cat, it should appear 100 degrees hotter after the cat, if same or less, cat is not working

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