1G high idle while driving in neutral

[JStrateger]

This only happens when I'm driving the car above 15mph but between shifting the car jumps to around 3000-3200rpms. Anytime in neutral above 15mph, the car jumps idle.

This is a 1G Eagle talon awd, 6-bolt, 16g turbo, fmic, 550cc injectors, walbro 255 fuel pump.

I searched but didn't find anything. Any ideas to what could cause this? Thanks guys.

 

[NateTheGreat]

hey guys. im new to dsm and i have a 91 talon tsi. just traded for it not to long ago, off topic best damn choice of my car career! but heres the bad. when im driving, between shifting and in nuetral any time over 15 mph, the car jumps way up to 3200 rpms! thats f*ing crazy. never experienced anything like this. ive been looking through some threads on here but none of them seem to be anything relatively close, unless its something stupid which it probably is, cause the guy i traded had some jimmy rigged things. but any help asap would be extremely aprreciated. thanx, nate.

 

[xreaction122]

check/test your ISC.

i had a terrible idle last winter like you and it was the isc

its attached to your throttle body on the bottom side

 

[NateTheGreat]

ok, my buddy has a spare one, but its off a 7 bolt. will it work for mine?

 

[ccb21]

Idel Speed control motor mite be a bit out of wack, tryed looking up that?

 

[Evil_speedracer]

I would check the ISC, but first you might wanna make sure that there are no vacuum leaks. Mine did this when I first got my new block in, I had a few cracked vacuum lines from sitting for 3 years. I just sprayed some carb cleaner around the lines and listened for the idle surge. Another possibility could be the MAF sensor going bad, I have seen those cause idle surge before too. Did you change the idle setting recently? If you set the BISS without grounding out the plug near the firewall (forgot what this is called) the car will have to correct the idle, which could also cause the issue you describe.

 

[JStrateger]

put in a diff isc, not that. havent tried anything else but im going crazy! could the maf go bad and not throw a code? cause i have what seems to be an original one with no air filter, just the sensor is exposed. but thats how i got it when i traded.

 

[Evil_speedracer]

Thats no good man, you might have a MAF problem. I don't know for sure if there would be a CEL, do you know someone who would swap MAFs with you for testing purposes?

 

[Zenja]

I recall seeing someone say that this can happen if you disable ABS the wrong way - maybe by pulling the wrong fuse.

 

[xreaction122]

they should work fine.

i have a 91 tb in my car with all the 1g sensors except the tps and it works like a champ

 

[NateTheGreat]

my buddy posted this for me, but its my car. its wierd you bring up abs. my abs light is on. and i heard its rare to have abs on a 1st gen talon. anywho, the ground wire is broke off the abs unit, but i dont understand what it could do with the abs.. if the maf is bad it would throw a code right? cause i unplugged it and the light came on. i can try to also find somebody with a diff maf, but i planned to get the upgraded one and the translator. is that ok?

 

[NateTheGreat]

ok i tried the other isc. it only took the revs to 2500 but other than that it still does it.

 

[PhenomTSi]

Hate to bring up an old thread, but there was never a resolve to this issue. I just bought a '91 TSi AWD and it has this issue. My ABS light is also on... Anyone have any suggestions?