Car revs up to 3grand with A/C???
09-20-2009, 08:38 PM
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Car revs up to 3grand with A/C??? I have had my car tuned about three times already and still not luck with this issue. The car has a couple of problems:
1. Without the A/C on the first initial start the car stutters like if you have it in a high gear to start with, then it is like someone flips a switch and the car wakes up and functions normal. This is hot or cold right after you start the car and try to take off.
2. With the A/C on, when i am on the highway its like having the cruise control on the car will stay reved up by itself, or if i push the clutch in, the car will rev to like 3 grand and then drop slowly after 5 secs or so. This also happens if i stop at a light, high revs then it slowly drops down to 1grand.
IAC sensor is brand new
MAF sensor is stock/ it did the same thing with a 5 **** ZO6 MAF..
IAT sensor is also good.
MS3, On afr 205's 66cc, 383 stroker
Can someone explain this??
1. Without the A/C on the first initial start the car stutters like if you have it in a high gear to start with, then it is like someone flips a switch and the car wakes up and functions normal. This is hot or cold right after you start the car and try to take off.
2. With the A/C on, when i am on the highway its like having the cruise control on the car will stay reved up by itself, or if i push the clutch in, the car will rev to like 3 grand and then drop slowly after 5 secs or so. This also happens if i stop at a light, high revs then it slowly drops down to 1grand.
IAC sensor is brand new
MAF sensor is stock/ it did the same thing with a 5 **** ZO6 MAF..
IAT sensor is also good.
MS3, On afr 205's 66cc, 383 stroker
Can someone explain this??
Last edited by Pheonix; 09-20-2009 at 11:49 PM.
09-21-2009, 08:56 PM
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I would be looking for a vacuum leak, A/C adds "bonus air" by
the IAC but it sounds like it's air you don't need (so you're
getting some you shouldn't be).
PCV system is a good place to start, are you noticing any other
symptoms of open-vac-ports (climate control flaky, odd whistles,
etc.)?
If you want to shoot some propane at it shade tree style, be
sure to unplug the IAC at a point where idle is steady so it
won't "fight" the effect.
the IAC but it sounds like it's air you don't need (so you're
getting some you shouldn't be).
PCV system is a good place to start, are you noticing any other
symptoms of open-vac-ports (climate control flaky, odd whistles,
etc.)?
If you want to shoot some propane at it shade tree style, be
sure to unplug the IAC at a point where idle is steady so it
won't "fight" the effect.
09-21-2009, 10:43 PM
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Cool man, ill try that. Today the car would surge at idle with the A/C on because the compressor would turn on and off because the idle was too low. I dont notice any whistles, but i will check all my hoses tomorrow. But what i dont understand is why it runs good without the A/C? The tuner told me that the reason why it stutters after i start it and drive away is because it is in closed loop, and then it jumps into open loop. Is there any truth to this?
09-22-2009, 10:01 AM
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Closed loop won't happen until ~140F coolant temp.
More likely the set afterstart enrichment is fading
out according to plan, uncovering the lean / stumble,
and it gets better again once fuel trimming starts
and/or the motor gets up to temp and needs less
enrichment.
A/C will cycle out if your idle is so unstable that the
"stall saver" logic wakes up.
More likely the set afterstart enrichment is fading
out according to plan, uncovering the lean / stumble,
and it gets better again once fuel trimming starts
and/or the motor gets up to temp and needs less
enrichment.
A/C will cycle out if your idle is so unstable that the
"stall saver" logic wakes up.
