Car dies when I let off the gas

[saiyansniper]

Checked the other threads to no avail.

Just picked up a 91 Eagle Talon TSI AWD after much searching and research. I bought it knowing it needed some repairs (throwout bearing, exhaust leak) which I'm prepared to do but this dying issue is throwing me for a loop.

Basically, if you get the rpms up past 2500 then take your foot off the accelerator then car just idles down then dies, all in one fell swoop. If you tap the gas pedal, it'll stay running, but if you just let it idle down it dies. Any ideas?

 

[CurtTSI]

This a typical problem when the ISC goes bad. Measure the coil resistances in your ISC. Resistances between the two center pins and the pins on each side should be between 28 and 33 ohms. If one of these resistances is very high, open circuit, that is your problem.

 

[saiyansniper]

That doesn't seem to be the problem. I checked the ISC on the datalogger and it appears to be functioning just fine.

To be more specific, the car dies when you have a decent rpm (2500+) and press the clutch in and just let it fall. When you just use some engine braking to slow the car down, then pull it out of gear around 1500-2000, it idles down just fine.

 

[bigbrothajake]

I've had that problem many times. I even thought is was my ISC motor as well. Every time it's come down to a vacuum leak. You'll have to go through all of you vacuum lines for your pollution controls and find the leak. Or you could go to www.taboospeedshop.com and remove all of your pollution control stuff and narrow down where your leak might be. You could also go to www.vfaq.com and get directions on how to make a leak tester.

Finally, it could also be possible that your power transistor has become partially unplugged- that can really mess up your idle. Trust me, I know

 

[saiyansniper]

ahh, the beloved vacuum problem. i'll make sure to check that tomorrow along with the plugs, plug wires, and umm, well i hope i find it out of that.

The idle problem isn't much of an issue now. I hooked up the datalogger and grounded the ignition timing adjustment plug and tweaked the BISS to get the idle back in the range. It is still idling between 850-1000, just kinda swaying back and forth.

any more ideas would be greatly appreciated.

 

[jeremy0203]

sounds just like my car, i have a rough erratic idle and whenever i bring the rpms to a decent number like 2500-3000 like yours or above and let off the gas it just drops down and the car dies. i read some people having stalling probs with lightened flywheels? i dunno i wish i knew

 

[saiyansniper]

The throttle switch/closed throttle position switch/idle switch is not making good contact and showing closed while the car is idling.

I checked the autoparts stores around here, they don't carry it. The only junkyard around with a dsm motor (the part is the same on the 16v motors as far as i can tell) wants to sell me the whole throttle body and i'm not even sure the switch is working in that car. Mitsu wants 98 bucks, Chrysler wants 116.

I'm gonna take it off tomorrow and see if i can fix the thing myself. It will show closed if you press on it but will open back up once you let off. Hopefully there is just some sort of buildup that can be cleaned out.

 

[jeremy0203]

is that the throttle position sensor

 

[BigAirSkier1580]

I had similar problems with my car a few weeks back. Turbo dodge guy told me to go ahead and clean out my TB. Suire enough, I cleaned it out, and my idle smoothed out and the stalling issue went away.

Give that a try.

 

[shamsulaswad]

mine also did the same thing. my only remedy is that to let the car warm enough before any driving. because mine have the same problem only when driving a few minutes. couple of minutes and stalling, she works like charm.

 

[saiyansniper]

I looked inside the throttle body this morning and it looked clean. I sprayed some throttle body cleaner inside. Same problem. Car was at regular temp, same problem. Drove it to the mechanics shop, same prob.

The actual part I'm talking about is on the opposite side of the throttle position sensor. Its a small screw looking switch, about half the length of your pinky finger, that is screwed in right past where the throttle cable ends. It has a small plunger on the end which gets pushed in by metal plate at the end of the cable. When the throttle cable is in the idle position, the switch should read closed and 0 volts. When the throttle is opened (to any degree) the plunger type thing comes out and the switch should read open and 12v. Mine is stuck open (i think i wrote closed last time).

The mechaninc guy has had some experience with DSM's and is pretty confident that the throttle switch is the problem. Downside is that its 98 bucks from Mitsu and 115 from Chrysler. My friend works in a parts department for Chevy so I can get a small discount, 20%, so ease the pain...

 

[CurtTSI]

$98 for a simple contact switch? Outrageous! Go to a local junk yard or buy one on Ebay. Right now there is a 1g throttle body on ebay, with all the sensors, and the current bid is only $5, with 5 hours to go. It even has the recent updated ISC. I would buy it myself, except that I already have 2 extra ISCs.

 

[saiyansniper]

WOOHOOO!!!!!

Manage to get one absolutely free. A local mechanic shop had a 420a laser sittin out front for quite some time. Went by and asked what they were gonna do with it and to see if I could get a part off of it. He said grab whatever I want that it was probably gonna get junked. Installed, problem fixed, me happy very much

 

[shamsulaswad]

glad you solved you problem. but please do update if the problem accurs again. by the way, did you just changer the whole TPS?