do these cars ever idle correctly? - Page 11 - 3000GT/Stealth International Message Center

91rtstealth · 02-14-2008, 10:30 AM

yeah..i don't know what to tell you there...these cars are certainly big pains in the a$$es..but whatever, u gotta love em...hah..

leet · 02-14-2008, 03:04 PM

mine actually idles better with the semi gutted maf then it did before lol

these cars don't make sense

OhioSpyderman · 02-14-2008, 04:54 PM

I've watched this thread and I just wanted to add that ALL 3 of our cars idle flawlessly at just about 750 RPM's.

92 TT, 93 VR4 and a 95 Spyder VR4....

Bob.

3Sfever · 02-14-2008, 09:42 PM

Quote:

Originally Posted by WhiteR/T

The only other thing I have tried, is to determine if I have a vacuum leak. I took out the isc and spun it all the way out, and unplugged it so it would stay out. While it was running, I screwed the biss screw all the way in, and the darn thing was still running! With those two air passages closed, wouldnt the engine choke itself out, or shouldnt it?

When I did exactly what you just described I could probably have stalled mine out if turning BISS screw closed. I did not turn the BISS screw all the way in, but it was idling steady at about 400 rpm at one point.

(note this was with engine warm, because if cold the FIAC is going to allow some air to bypass)

It sure seems like extra air is getting in somewhere.

Quote:

Originally Posted by WhiteR/T

I'm getting really impatient with this thing, and dont feel like spending any more $$.

This really stinks, I wish you could find the problem.

I am having the same experience as OhioSpyderman, after replacing my ISC/IAC, mine is idling perfect.

.

Hammer · 02-15-2008, 12:12 AM

Quote:

Originally Posted by WhiteR/T

Sorry I havent replied in a while, I dont visit here often anymore, I've been too busy.

I still have all problems, and more. Now I am getting a slight grinding noise from the drivers side of the engine. I dont think its anything to do with the engine, because it isnt consistent. Its a random noise. I hope its a serpentine idler bearing or alternator bearing or something, I really dont know what it is.

The only other thing I have tried, is to determine if I have a vacuum leak. I took out the isc and spun it all the way out, and unplugged it so it would stay out. While it was running, I screwed the biss screw all the way in, and the darn thing was still running! With those two air passages closed, wouldnt the engine choke itself out, or shouldnt it? I'm getting really impatient with this thing, and dont feel like spending any more $$.

I know one thing, next time I buy a car, there is going to be much more research.

A new ISC costs about $100 dollars. How many man hours do you have into your car already? Isn't your time worth that 100 dollars?
Although you are screwed now that you messed with the BISS screw, even with a new ISC you will have a messed up idle now.
Hint never ever turn the BISS screw. You never have too.

If the car is stock and a new ISC does not fix the idle then most likely cause
is a bad ECU. Assuming the BISS screw is still in stock position.
It could be gas or spark problems but those would show up in other areas besides idle.

WhiteR/T · 02-15-2008, 04:50 PM

Well I really havent spent a ton of time on it, I was just a little frustrated when I wrote that, I have since simmered down. I do know what you mean though.

I do have a newer ISC, it isnt the brown one, it is all black, do those "go bad" like the original brown ones? When I have it out and plugged in, and turn on the ignition, it does screw in a bit, to allow air to enter. When I shut it back off, it spins back out. I would assume that if my ISC is bad, it wouldnt do that.

For the heck of it, I yanked the front valve cover to see if any of the lobes looked bad, and they all looked fine. So at least my grinding noise isnt coming from there...

I just wish it was warmer out. My truck is in the heated shop in the process of going back together.

I would think that most people with an idle problem have touched the BISS, why do you say I'm screwed?

I know of another stealth that is a half hour away, maybe some afternoon he'd let me swap ISC's and see if that makes any difference. Wouldnt hurt...

Thanks for those who are still listening to me complain about my car. Someday it will be nice to drive...

Edit, I forgot that it still does have a miss after plugs and wires. Could a plugged/non working injector cause a bad idle and "chugging"?

Street_Chally73 · 02-15-2008, 08:53 PM

WhiteR/T, when you had the ECU apart, did you notice if any of the traces were damaged? I took my ECU out of my R/T TT the last time I was home on break and while it was definitely repaired before, I'm almost positive it's causing my problems 'cause there is some crap underneath one of the capacitors. Sorry you're having so many problems with your car. I figured it was a pretty good deal for the mileage/condition back when you asked about it. I assumed the chugging problem was just from these cars wanting to run in a higher RPM range than we're used to...Turns out, they are supposed to be like the other cars, but be more fun than others when they are running correctly. This summer I'm probably going to send my ECU/ECS out to AvPro or ECMToGo.com, so I'll definitely let you know if that corrects the problem. I also plan on getting a new ISC, doing a pressure test (probably half my problem), and cleaning the injectors (new O-rings, too). I have newer coil packs, wires, and plugs in it now, so that shouldn't be my problem. I have noticed that when my stuttering occurs, it sounds as if I am arching/spark cut, so hopefully it's something to do with just the ECU.

WhiteR/T · 02-15-2008, 10:53 PM

Everything looked fine when I had the ECU out, I didnt see anything burnt or melted.

mikes2nd · 02-16-2008, 03:46 PM

okay... if you have the "original" ecu in your 91-93... 99% of the time its got broken traces. Just because you change out the caps means the broken traces are still there.

hhmm how do you pressure test a NA car?

3Sfever · 02-17-2008, 02:33 PM

The purpose of the BISS screw IS to adjust the idle. . . . the one we normally do not want to fool with is the SAS screw. It holds the throttle plate open just a tad to keep it from touching the side of the body bore.

The Wiki has a good writeup on the adustment of these:
http://www.3si.org/wiki/index.php/Idle_Speed_Adjustment

.

02-14-2008, 10:30 AM	#101 (permalink)
91rtstealth Dru Join Date: Sep 2002 Location: Lehighton, PA Drives: 91 Stealth R/t Stock Trader Rating: (0)	Re: do these cars ever idle correctly? yeah..i don't know what to tell you there...these cars are certainly big pains in the a$$es..but whatever, u gotta love em...hah..

02-14-2008, 03:04 PM	#102 (permalink)
leet Now with 100% more NSX Join Date: Feb 2004 Location: Belgium / Michigan Drives: 95 NSX and 92 TT Trader Rating: (24)	Re: do these cars ever idle correctly? mine actually idles better with the semi gutted maf then it did before lol these cars don't make sense __________________ the stealth is officially for sale, PM for info

02-15-2008, 04:50 PM	#106 (permalink)
WhiteR/T One too many projects... Join Date: Oct 2007 Location: New Richmond, WI Drives: Stock 92 Stealth R/T Trader Rating: (2)	Re: do these cars ever idle correctly? Well I really havent spent a ton of time on it, I was just a little frustrated when I wrote that, I have since simmered down. I do know what you mean though. I do have a newer ISC, it isnt the brown one, it is all black, do those "go bad" like the original brown ones? When I have it out and plugged in, and turn on the ignition, it does screw in a bit, to allow air to enter. When I shut it back off, it spins back out. I would assume that if my ISC is bad, it wouldnt do that. For the heck of it, I yanked the front valve cover to see if any of the lobes looked bad, and they all looked fine. So at least my grinding noise isnt coming from there... I just wish it was warmer out. My truck is in the heated shop in the process of going back together. I would think that most people with an idle problem have touched the BISS, why do you say I'm screwed? I know of another stealth that is a half hour away, maybe some afternoon he'd let me swap ISC's and see if that makes any difference. Wouldnt hurt... Thanks for those who are still listening to me complain about my car. Someday it will be nice to drive... Edit, I forgot that it still does have a miss after plugs and wires. Could a plugged/non working injector cause a bad idle and "chugging"? __________________ '92 Pearl White R/T Driver, pretty much stock. 1967 Dodge D200 5.7 HEMI 1971 Dodge Challenger 383/727

02-15-2008, 08:53 PM	#107 (permalink)
Street_Chally73 RTBOOST Join Date: May 2007 Location: Florence, WI Drives: '91 Stealth R/T TT Trader Rating: (8)	Re: do these cars ever idle correctly? WhiteR/T, when you had the ECU apart, did you notice if any of the traces were damaged? I took my ECU out of my R/T TT the last time I was home on break and while it was definitely repaired before, I'm almost positive it's causing my problems 'cause there is some crap underneath one of the capacitors. Sorry you're having so many problems with your car. I figured it was a pretty good deal for the mileage/condition back when you asked about it. I assumed the chugging problem was just from these cars wanting to run in a higher RPM range than we're used to...Turns out, they are supposed to be like the other cars, but be more fun than others when they are running correctly. This summer I'm probably going to send my ECU/ECS out to AvPro or ECMToGo.com, so I'll definitely let you know if that corrects the problem. I also plan on getting a new ISC, doing a pressure test (probably half my problem), and cleaning the injectors (new O-rings, too). I have newer coil packs, wires, and plugs in it now, so that shouldn't be my problem. I have noticed that when my stuttering occurs, it sounds as if I am arching/spark cut, so hopefully it's something to do with just the ECU. __________________ '73 Dodge Challenger 340.............................(X) '91 Firestorm Red Stealth R/T TT...................(X)

02-15-2008, 10:53 PM	#108 (permalink)
WhiteR/T One too many projects... Join Date: Oct 2007 Location: New Richmond, WI Drives: Stock 92 Stealth R/T Trader Rating: (2)	Re: do these cars ever idle correctly? Everything looked fine when I had the ECU out, I didnt see anything burnt or melted.

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02-17-2008, 02:33 PM	#110 (permalink)
3Sfever Forum Member Join Date: May 2004 Location: Virginia Drives: '91 Stealth TT Trader Rating: (5)	Re: do these cars ever idle correctly? The purpose of the BISS screw IS to adjust the idle. . . . the one we normally do not want to fool with is the SAS screw. It holds the throttle plate open just a tad to keep it from touching the side of the body bore. The Wiki has a good writeup on the adustment of these: http://www.3si.org/wiki/index.php/Idle_Speed_Adjustment .