do these cars ever idle correctly? - Page 5 - 3000GT/Stealth International Message Center

WhiteR/T · 10-28-2007, 09:23 AM

TPS = Throttle Position Sensor. Its on the front of the throttle body. You can adjust it CW or CCW. I adjusted mine yeterday just messing around with it, no meters or anything. It is quite a bit better, but the chugging is still there. First gear has immensely improved. Still think my IAC is bad...

91rtstealth · 10-29-2007, 08:04 AM

white r/t...what did you do exactly do get the chugging to go away/improve...the stupid idleing doesn't bother me as much as the chugging..i can't stand that..i want to fix that mainly...i'm fairly certain teh chugging is cuz of my bad IAC..but what areyou saying about the TPS..how did you "adjust it"?

3Sfever · 10-29-2007, 09:44 AM

I mentioned this earlier, but in a different context.

One way to determine if the ISC/IAC is the problem is to disable it.

Its purpose is to allow the ECU to control the idle speed by allowing air to bypass the throttle plate. If it is stuck open, or is erratic, then the ECU has no control.

If you want to disable it as a test --> Remove the ISC from the throttlebody, spin the plunger out all the way, so that when installed there will be no bypass air coming from ISC. Do not hook up the wiring harness, so that the plunger will stay out.

If the bucking goes away, then you know it was the ISC. If it does not go away, then mostly likely something else is leaking air.

This test worked great for me. I even drove it with the ISC disabled for several months.

92_stealth · 10-29-2007, 09:59 AM

i had similar problems, idling horribly, tach jumping around everywhere, and the idling really low, "chugging" possibly what your saying, and after trying many different things, mine turned out to be the ECU.... :/ dunno if that helps, but that's what my problem was.

3Sfever · 10-29-2007, 10:04 AM

Quote:

Originally Posted by 92_stealth

i had similar problems, idling horribly, tach jumping around everywhere, and the idling really low, "chugging" possibly what your saying, and after trying many different things, mine turned out to be the ECU.... :/ dunno if that helps, but that's what my problem was.

Oh yeah . . . good point.

I was having problems with ECU caps and ISC/IAC at the same time. Made it really tough to diagnose.

Ended up they were both bad. Made me wonder if one caused the death of the other.

.

WhiteR/T · 10-29-2007, 10:30 AM

Ok well more bad news. The chugging went away in the most part in first, but is still pretty evident after driving it for a while, and still very annoying. The caps are on order, should be here mid week.

91rt, just loosen the top and bottom screw on the tps, dont take them out. Tighten them back up just so that you are positive it wont move, but you can still twist it. Just play with it a bit. Try it in one spot, if it doesnt get better, stop, pop the hood, turn it a bit, and try it again. Not very precise, but it works.

Oh, and dont get the caps from that digi key place like the wiki recommends, I'm only one state away, and they charged me $8.50 to ship 2 caps, and the one that was on backorder they charged me $4.50 to ship. I am not very happy. The local radio shack said they could order them for me for $15 total, I spent almost $20 at that digi key place. Yeah a few bucks difference doesnt sound like much, but I could have had them in by now if I wouldve went to RS. That shipping is unreal...

I'll have to screw it in and do what you say, thanks a lot guys for helping out.

91rtstealth · 10-29-2007, 10:31 AM

did you guys end up getting new ECU's or just having the caps replaced....if so, who replaced the caps for you? and how much did it cost to fix?

91rtstealth · 10-29-2007, 10:35 AM

i posted that msg just as you posted your msg about where to get the caps..hah...so to my next question..how do you replace them? I'm electronically savy, but I don't nkow if I wanna mess with an ECU...what's the proecdure..what do i need..etc..i figure it's probably a good idea to replace them neways...whether they are bad or not..the car is totally original,..so I my as well

3Sfever · 10-29-2007, 01:56 PM

I replaced the caps on ECU myself. You can start with wiki for instructions. A search for "ecu" will point to link.

I got lucky and bought them thru work, only about $2.00 total, including my share of shipping. They were shipped with other stuff.

91rtstealth · 10-29-2007, 08:00 PM

cool..i'll have to look into it...the car was manufactured in 1990..so yeah, those caps are probably shot...everything on the car is original for the most part...so i bet the IAC is bad too...we'll see after teh caps..but that won't be until a few months...the car gets put away in a few days..but who knows..i might mess with it here and there...i'm anxious to see what white r/t has to say after he puts his caps in...

10-28-2007, 09:23 AM	#41 (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? TPS = Throttle Position Sensor. Its on the front of the throttle body. You can adjust it CW or CCW. I adjusted mine yeterday just messing around with it, no meters or anything. It is quite a bit better, but the chugging is still there. First gear has immensely improved. Still think my IAC is bad... __________________ '92 Pearl White R/T Driver, pretty much stock. 1967 Dodge D200 5.7 HEMI 1971 Dodge Challenger 383/727

10-29-2007, 08:04 AM	#42 (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? white r/t...what did you do exactly do get the chugging to go away/improve...the stupid idleing doesn't bother me as much as the chugging..i can't stand that..i want to fix that mainly...i'm fairly certain teh chugging is cuz of my bad IAC..but what areyou saying about the TPS..how did you "adjust it"?

10-29-2007, 09:44 AM	#43 (permalink)
3Sfever Forum Member Join Date: May 2004 Location: Virginia Drives: '91 Stealth TT Trader Rating: (3)	Re: do these cars ever idle correctly? I mentioned this earlier, but in a different context. One way to determine if the ISC/IAC is the problem is to disable it. Its purpose is to allow the ECU to control the idle speed by allowing air to bypass the throttle plate. If it is stuck open, or is erratic, then the ECU has no control. If you want to disable it as a test --> Remove the ISC from the throttlebody, spin the plunger out all the way, so that when installed there will be no bypass air coming from ISC. Do not hook up the wiring harness, so that the plunger will stay out. If the bucking goes away, then you know it was the ISC. If it does not go away, then mostly likely something else is leaking air. This test worked great for me. I even drove it with the ISC disabled for several months. __________________ -Ron '91 Stealth TT purchased Aug 2004

10-29-2007, 09:59 AM	#44 (permalink)
92_stealth Forum Member Join Date: Apr 2007 Location: Kalamazoo, MI Drives: A semi-broken one Trader Rating: (0)	Re: do these cars ever idle correctly? i had similar problems, idling horribly, tach jumping around everywhere, and the idling really low, "chugging" possibly what your saying, and after trying many different things, mine turned out to be the ECU.... :/ dunno if that helps, but that's what my problem was. __________________ everything stock........for now

10-29-2007, 10:30 AM	#46 (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? Ok well more bad news. The chugging went away in the most part in first, but is still pretty evident after driving it for a while, and still very annoying. The caps are on order, should be here mid week. 91rt, just loosen the top and bottom screw on the tps, dont take them out. Tighten them back up just so that you are positive it wont move, but you can still twist it. Just play with it a bit. Try it in one spot, if it doesnt get better, stop, pop the hood, turn it a bit, and try it again. Not very precise, but it works. Oh, and dont get the caps from that digi key place like the wiki recommends, I'm only one state away, and they charged me $8.50 to ship 2 caps, and the one that was on backorder they charged me $4.50 to ship. I am not very happy. The local radio shack said they could order them for me for $15 total, I spent almost $20 at that digi key place. Yeah a few bucks difference doesnt sound like much, but I could have had them in by now if I wouldve went to RS. That shipping is unreal... I'll have to screw it in and do what you say, thanks a lot guys for helping out.

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10-29-2007, 10:31 AM	#47 (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? did you guys end up getting new ECU's or just having the caps replaced....if so, who replaced the caps for you? and how much did it cost to fix?

10-29-2007, 10:35 AM	#48 (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? i posted that msg just as you posted your msg about where to get the caps..hah...so to my next question..how do you replace them? I'm electronically savy, but I don't nkow if I wanna mess with an ECU...what's the proecdure..what do i need..etc..i figure it's probably a good idea to replace them neways...whether they are bad or not..the car is totally original,..so I my as well

10-29-2007, 01:56 PM	#49 (permalink)
3Sfever Forum Member Join Date: May 2004 Location: Virginia Drives: '91 Stealth TT Trader Rating: (3)	Re: do these cars ever idle correctly? I replaced the caps on ECU myself. You can start with wiki for instructions. A search for "ecu" will point to link. I got lucky and bought them thru work, only about $2.00 total, including my share of shipping. They were shipped with other stuff.

10-29-2007, 08:00 PM	#50 (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? cool..i'll have to look into it...the car was manufactured in 1990..so yeah, those caps are probably shot...everything on the car is original for the most part...so i bet the IAC is bad too...we'll see after teh caps..but that won't be until a few months...the car gets put away in a few days..but who knows..i might mess with it here and there...i'm anxious to see what white r/t has to say after he puts his caps in...