very high idle???
Thread Starter
Cruising
Joined: May 2012
Posts: 12
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very high idle???
I have a 99 frc m6, Sometimes after driving for a while, when I push the clutch in the motor revs up to 1500 sometimes 2500 rpms, a/c on or off, has it done it both ways. it will continue to idle this high until i turn it off and restart it. it usually idles at 950 or so but occasionally it will idle at 650-700, does not matter if its hot or cold, the check engine light does not come on when this occurs, however, I do have the occasional p1125 p1276 p1281 p1286 c1278 codes, but these codes are not set when the idle decides to take off and do its own thing. Can anyone tell me what all controls the idle ? I have been looking at replacing the tac module for the codes being thrown but now I think it may be the pedal reading incorrectly. any ideas?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
What MODs do you have??? Have you checked for vacuum leaks????
Is the PCM professionally tuned???
Does the air ducting between the MAF and the Throttle Body have a good seal and no air leaks???
Bill
Is the PCM professionally tuned???
Does the air ducting between the MAF and the Throttle Body have a good seal and no air leaks???
Bill
Thread Starter
Cruising
Joined: May 2012
Posts: 12
Likes: 0
long tube headers, straight pipe exhaust, vararam cai, the tune is stock to my knowledge.
I have checked for vacuum leaks and I cannot find any,
and it appears to seal well between the throttle body and maf, no leaks that I can find.
I have checked for vacuum leaks and I cannot find any,
and it appears to seal well between the throttle body and maf, no leaks that I can find.
Racer
Joined: Aug 2011
Posts: 279
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From: MN
Coming from the old-style engines, that random idle screams vacuum leak to me. However, you do have more air coming in and exhaust going out on a factory tune from the CAI and headers. It may very well be time for a tune sir.
Tech Contributor
Joined: Aug 2008
Posts: 2,902
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From: Oak Hill Virginia
Did you check the connection of the PCV hose to the throttle body? It is extremely common for that elbow to rot resulting in a significant vacuum leak. Make sure you look at the underside of the hose as well... don't just look at it from the top.
Thread Starter
Cruising
Joined: May 2012
Posts: 12
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ok thanks ill check again for the leaks, however I have started to notice a pattern, the idle always jumps over 1100 after I clear the codes for p1125,p1276,c1278. Also, it seems to jump in rpm right before it throws these codes. It happened again this morning on my way to work. It went into REP mode idle was 950 or so before, I came to a stop and the idle was at 650, I cleared the codes and as soon as I cleared them the idle jumped to 1500??? and then other times I clear the codes and it will idle at 650 for days with out any trouble !! Im starting to think now maybe the pedal is reading incorrectly and telling the computer Im pressing it at idle when im not? is that possible ?
