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Idle problem

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tnubzdsm

Probationary Member
6
0
Jun 4, 2014
Marion, Ohio
Okay so I have a 1998 eclipse gst with a 6 bolt swap. I have seem to be having a idle problem, here's some details, once I start the car it will idle fine but once the car starts to get warmed up it will start to idle high, once I've been driving it for a little it will eventually start to idle at 2 1/2 to 3k rpms. I replaced the iac and cleaned the throttle body and I could really use some help. Thank you.
 
Possibly the tps or try adjusting the biss (base idle set screw on top of the TB). I had the same problem on my 420a and after cleaning the throttle body and IAC with no results I swapped the tps with one from the junkyard and bam..problem solved.
 
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I had the same problem with my 98 RS. even idled at the same numbers! the moron that had the car before me treated the throttle stop screw as an idle adjustment! if its the same problem AND if the GST is the same as the RS in this regard here's what I did. loosen the bolts that hold the throttle cable so you can create some slack in the cable (mine had 2 bolts right in front of the throttle body but yours is probably different). once you can get slack in the cable adjust the throttle stop (set screw that hits when you let off the gas). keep backing it out until there's a space between the end of the screw and the piece of the throttle it would hit. then screw it in until it touches, then add an extra turn more (or better yet, turn until the throttle doesn't stick at all when you snap it shut). once that's done, adjust the cable so that there's a tiny amount of slack in it (you DONT want it tight or you'll have major idle problems as well). tighten up those bolts and see how she runs. FYI it might take a few on/off cycles for the computer to learn where the new position for the IACV motor should be so it might idle high or low at first so give it some time. also if you have a scan tool that shows real time events, you'll know you got the throttle cable right when the throttle position sensor (TPS) shows as close to 0% when off the gas and as close to 100% when floored as you can get it.
as I said before this might not apply perfectly to your car, hopefully it does or hopefully it helps someone else.
let me know and good luck!
 
Did either of your cars throw a check engine light at all? I'm having the same issue and the warmer it is outside the faster the idle goes up and I have had it up to 3.5k but sometimes if I hop on the freeway for a while it'll go down.. surprisingly the check engine light has never came on..
 
Did either of your cars throw a check engine light at all? I'm having the same issue and the warmer it is outside the faster the idle goes up and I have had it up to 3.5k but sometimes if I hop on the freeway for a while it'll go down.. surprisingly the check engine light has never came on..

Unfortunately check engine doesnt apply to my car as my factory computer is unhooked completely and everything is run by a haltech ECU. so things can be all kinds of F'd up in my car and I wont get a check engine light at all. try the steps I outlined in making sure your throttle snaps shut nicely and leaves a slight amount of slack in the cable (not visible slack! just enough that there's no tension on it). if it still idles high when hot turn the idle screw until it slows down to where you want it. then hopefully it idles good cold. if that doesnt work you may want to test/clean your idle control motor. if your car has cruise control you can unhook that as well to rule it out. I can walk you through how to do that to test if you want.
let me know how it goes.
 
Ya the guy who owned the car before me was an idiot and I've been finding stuff left and right..but I do have some slack in the cable not too much but it's there.. I do know that if the rpms go up and I turn the car off unplug the IAC turn the car on then off and plug it back in then turn it back on the rpms will drop down a bit to around 1200. I do however know there is a different turbo from what I've been told by people on my car that's for a older eclipse And when the guy changed it out he never reconnected the boost control solenoid. So there's just a hose going from the waste gate to the boost source wich is not on the turbo itself it's on the j pipe. Do you think that would have anything to do with it?
 
This post is a year oldLOL regardless if you have a 4g63 or 420a you MUST test your tps and isc/ IAC with a multimeter, then adjust your throttle cable and biss (turbo) accordingly. You should never have to adjust the stop screw.
 
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