Idle problems. way to high.

[John_GST]

Ok I have a 2g GST and ever since i bought the car it has had an idle problem. When I start the car cold it will hang at about 1600 rpm but as it warms up the idle will rise all the way upto about 2600 rpm. I am concerned about this and would like to get it fixed as soon as possible. any help is appreciated. I have searched this, but I didn't find specific simialaritys in the search.
Thanks,
John_GST

 

[bob123131]

I hada similar problem once and it was either my tps or isc i'm not sure which though try searching under both of those.

 

[pooker]

If your maf has not been touched I am betting money on the isc.

 

[John_GST]

where is the isc located?

 

[JayRolla]

Bottom left of TB. Big sensor with a plug going to it.

 

[merqury]

ISC the idle control valve is probably the problem. There is also a biss screw right on the throttle body trying adjusting that maybe it will help. Moreover, my talon had the same problem and I changed the ISC and the car idled right at 850rpm, which was perfect! If the ISC looks worn out I would replace it!

 

[John_GST]

ISC the idle control valve is probably the problem. There is also a biss screw right on the throttle body trying adjusting that maybe it will help. Moreover, my talon had the same problem and I changed the ISC and the car idled right at 850rpm, which was perfect! If the ISC looks worn out I would replace it!

hey man thanks for breakin it down for me. the biss looks like it has been screwed all the way into the throttle body like all the way down do u think if i back it out it would help?

 

[funkbuster]

my cousin's 90 gst (my old one) was idleing at around 3k when he bought it from his dad/my uncle (person I sold it to). He ended up putting a MAF sensor on it and he had to ground something out on the ecu and it fixed it. Just the MAF didnt help any, but once he grounded out the ecu thing, it ran great, and has every sence.

 

[John_GST]

my cousin's 90 gst (my old one) was idleing at around 3k when he bought it from his dad/my uncle (person I sold it to). He ended up putting a MAF sensor on it and he had to ground something out on the ecu and it fixed it. Just the MAF didnt help any, but once he grounded out the ecu thing, it ran great, and has every sence.

What might the "ecu thing" be? i haven't had time to check any of these things since i dont get back from college till friday of this week. does anyone know about unhooking the battery to reset the ecu codes does that do anything i know i have heard people talking about that before but im not sure if it will portray to what is wrong with mine.

 

[romeen]

hey man thanks for breakin it down for me. the biss looks like it has been screwed all the way into the throttle body like all the way down do u think if i back it out it would help?

Backing the BISS screw out will RAISE the idle even more. You can try to screw it in more to see if that will lower your idle but it sounds like your problem may lie elsewhere. Does your idle constantly go up and down? If it does then you're experiencing idle surge. There is a good write up (I believe it's in the tech section) on how to narrow down the possible causes of idle surge and hopefully fix the problem.

Edit: Here is the link to the idle surge "trouble shooting" write up: http://www.dsm.org/how-tos/tttt/tttt3.html

 

[John_GST]

Backing the BISS screw out will RAISE the idle even more. You can try to screw it in more to see if that will lower your idle but it sounds like your problem may lie elsewhere. Does your idle constantly go up and down? If it does then you're experiencing idle surge. There is a good write up (I believe it's in the tech section) on how to narrow down the possible causes of idle surge and hopefully fix the problem.

Edit: Here is the link to the idle surge "trouble shooting" write up: http://www.dsm.org/how-tos/tttt/tttt3.html

No the idle doesn't surge its steady at 1500-1600 cold and steady at 2400-2600 when it gets warmed up. it doesnt go down or up while idleing. so i guess that would rule out the surge. thanks for the info on the biss screw thats what i was thinking it would do is raise it more