1994 Chevy S10, 2.2 motor, 2wd, 111,xxx miles. No problems when I parked Friday afternoon. When I got in Friday night and cranked up, the idle went so high I thought it would redline. It was like I had the pedal pressed all the way to the floor. I have looked up everything I can find on line. I've checked the MAP, TPS, IAC, all vacuum hoses. I had a MAP voltage high code. I unplugged the MAP and when I crank up, it sputters, the rpm is low, then it stalls out. I changed the MAP, but it still idles extremely high and now I'm getting MAP voltage low code. Somebody please help.
MOOSE843
Check the hose that goes from the intake to the PCV valve and if that's not the problem go over all the vacuum hoses again.
High idle is caused by too much air:
1. Bad/dirty IAC
2. Vacuum leak
3. Dirty throttle body, especially around the butterfly.
4. Sticky throttle
1. Bad/dirty IAC
2. Vacuum leak
3. Dirty throttle body, especially around the butterfly.
4. Sticky throttle
I'd clean up the IAC as it's probably the easiest plan of attack. After that, clean up the throttle body, spray it off with some throttle body cleaner. After that, look for vacuum leaks. I know this probably isn't your issue, but my buddy's Honda had the same problem yesterday, it ended up being a leaking intake manifold gasket.
A way that I have used in the past to look for vacuum leaks (probably not the best way, but it works alright) is take a few puffs of a cigar, cover up the butterfly and find a vacuum hose to blow into. Take a puff of the cigar and blow it into the hose, it makes it painfully obvious where it's leaking from, if there is one.
This is how we found out that my buddy's intake gasket was leaking.
Oh god now I feel so embarrassed for using such a half-assed way of finding a vacuum leak
A way that I have used in the past to look for vacuum leaks (probably not the best way, but it works alright) is take a few puffs of a cigar, cover up the butterfly and find a vacuum hose to blow into. Take a puff of the cigar and blow it into the hose, it makes it painfully obvious where it's leaking from, if there is one.
This is how we found out that my buddy's intake gasket was leaking.
Oh god now I feel so embarrassed for using such a half-assed way of finding a vacuum leak
Yeah, you can use carb cleaner or starting fluid. Just make sure the engine is cold or you'll risk a fire. I couldn't see the smoke method working in this case considering all the air that's moving around the engine compartment from the clutch fan.
Yes, I familiar with using a smoke machines and how they work. I can't see blowing a hit of cigar smoke through a hose working.
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