high idle confusion
#1
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Location: Newington, CT
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Car: '85 Firebird, '74 Nova
Engine: 2.8, 5.7
Transmission: T5, TH350
Axle/Gears: 3.42 open, 3.08 open
high idle confusion
I've got a bit of a strange problem.
When my car is fully warmed up, it idles fine at about 700-800rpm. But when you start going past about 5mph and the car is in neutral, it won't idle below 1500rpm, unless the car is basically stopped.
What's the problem?
When my car is fully warmed up, it idles fine at about 700-800rpm. But when you start going past about 5mph and the car is in neutral, it won't idle below 1500rpm, unless the car is basically stopped.
What's the problem?
#4
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Location: Inyokern, CA
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Car: 1984 Camaro Sport Coupe
Engine: 2.8 L v6 (Carbureted)
Transmission: Automatic
Re: high idle confusion
just throwing this out there...what about a speed sensor? Ya think that went bad? I've got a bad one that keeps throwing my SES light, but nothing physically changes that I notice. I'm gonna stop while I'm only a little behind, because I don't know anything about your problem lol
#5
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Car: 1988 Camaro RS
Engine: 2.8L of Raw POWER!!!
Transmission: Stick Shift
Axle/Gears: 3.42's
Re: high idle confusion
completely normal. It's programmed into the ECM to open the IAC valve when you'r moving. It's designed to help reduce HC emissions on decel and to reduce driveline shock if you were to release the clutch. All 3rd gens do it, it's just that it's only noticable on manual trans cars.
#6
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Car: '85 Firebird, '74 Nova
Engine: 2.8, 5.7
Transmission: T5, TH350
Axle/Gears: 3.42 open, 3.08 open
Re: high idle confusion
completely normal. It's programmed into the ECM to open the IAC valve when you'r moving. It's designed to help reduce HC emissions on decel and to reduce driveline shock if you were to release the clutch. All 3rd gens do it, it's just that it's only noticable on manual trans cars.
I also had a problem today where the car's idle dropped to about 500 or so and ran rough, which is leading me to believe that my IAC is on it's way out.
Edit: there is also a dry vacuum line at the back on my intake plenum, but I don't think a tiny leak would cause something as random and severe as this. Either way I will be replacing the vacuum line.
Last edited by poppn; 11-21-2007 at 12:10 PM.
#7
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Car: 87 trans am
Engine: 5.7
Transmission: t-5
Axle/Gears: 9 bolt posi 3:27
Re: high idle confusion
its not suppose to drop below 1500 when your slowing down but when yer at a stop idle should be about 800. yer IAC could be or your vacuum might be leaking somewhere. check the vac lines then the IAC
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