Car has trouble idling

[Turbogst15]

I have a 98 gst 5sp and here is my problem. I'v been having a problem where my car would not idle at all. I cleaned out my isc sensor and after this it idled perfect when i first started the car and drove it. After i shut it off then started it again it would not idle. So i changed the isc sensor with another one i have and it did the same thing. Worked perfect untill i shut the car off then when i started it back up did not idle, but this time i still tried driving it around and after about 5 min of driving the idle came back. I shut it off again, stopped idling and this time it never came back and drove for about 15 min. Then thought it might be my tps sensor but the one i have in is only 1 year old??? Would it go bad that fast.. I bought it brand new.

 

[DanThMan1983]

You are on the right track. Do you have a logger? Im wondering if you have unmetered air coming in some where after the MAF, if air was coming in after the MAF it would cause some driveability concerns. Does it only run rough at idle? I have a 1g and I had a similar concern and it was the wire going to my throttle closed sensor, its a one wire sensor on top of the throttle body. Get the car running, wiggle wires around see if you get anything to change. Sorry if I am not much help just throwing some things out there.

 

[Turbogst15]

Yea, i do have a logger, dsmlink, but im not too sure how to tell if a sensor is bad or not. I also know im not getting any extra air in after the mas because i recently did a boost leak test and there were no leaks and i have the nozzles on my intake that are not in use capped off and sealed.

 

[Gstclipse69]

TPS Adjustment
That link will tell you if the tps is adjusted correctly.

 

[Turbogst15]

I took my old isc, cleaned it, put it in, and it was idling good for a while. Then it started to idle surge between 1400-1900 rpm. Then after a couple start ups and driving it won't idle again. I tested my tps and everything was good so its not that. How do you guys usually clean your isc?

 

[stomp]

From what I read you have to basically unscrew your isc so that the needle goes all the way back before reinstall ..So take your neg. off the battery ,take back off isc,make sure isc is decompressed(in) and reinstall,hook back up battery should be good to go

 

[Hmong_1G]

Gotta do the BISS adjustment. VFAQ.com is your best friend.
Far aas I know, by doing the BISS adjustment, you are also correcting the proper step for the ISC. ( the ISC is a stepper motor idle control unit)

 

[kapllia]

first hold throttle cable , is it run rough if yes check tune up
if no still doing same thing

if you have maf if yes unplug and start the car if idle . if it idle then you rev
just a little ,if do any more, your problem solve

 

[kapllia]

one thing check
blow of valve
isc
tps
maf
translator



to me sound you have a vacum leak

best to find vacum leak brake clean but be careful
you will extra hep, one start car

spay around vacum area if it leak idle should go higher

 

[spawn87]

im still new to dsm but the dsmlink is a modified computer for the car that replaces the stock one, right?

well if that is the case try looking at you dsmlink and run a diagnostic to make sure it is not the reason ## car wont idle.

sorry if im wrong, its just a suggestion.