Idle problem, car stalls if I don't hit the brakes?

[DaJackal]

Ok guys, now I need some help.

My car is a '95 Eclipse N/T, 420a all stock, with a manual transmission. I bought the car 2 months ago, so I'm not yet all familiar with it. I have a Haynes manual and a service repair manual.

The problem: my car stalls when I come to crossroads and press the clutch. The rpms go down to 200-400, and car nearly dies (or dies). The startup is a bit difficult too, I have to rev it up a bit to get the car running. This happens only when the engine is cold, after driving 20-30km this problem is usually gone.

Yesterday I noticed that if I manage to hit the brakes before the rpms go below 1500 the car will not do this "rpm dive".

Is there some sensor which the ECU passes when brake pedal is pressed? That would explain this behaviour. I know my TPS is or might be misfunctional, but... does the ECU reject for example the TPS signal when brake pedal is pressed?

 

[GSTRyder]

Ok guys, now I need some help.

My car is a '95 Eclipse N/T, 420a all stock, with a manual transmission. I bought the car 2 months ago, so I'm not yet all familiar with it. I have a Haynes manual and a service repair manual.

The problem: my car stalls when I come to crossroads and press the clutch. The rpms go down to 200-400, and car nearly dies (or dies). The startup is a bit difficult too, I have to rev it up a bit to get the car running. This happens only when the engine is cold, after driving 20-30km this problem is usually gone.

Yesterday I noticed that if I manage to hit the brakes before the rpms go below 1500 the car will not do this "rpm dive".

Is there some sensor which the ECU passes when brake pedal is pressed? That would explain this behaviour. I know my TPS is or might be misfunctional, but... does the ECU reject for example the TPS signal when brake pedal is pressed?

Sounds like you have a vacuum leak somewhere. Is the check engine light on? Best may to find the leak is have the car running and spray propane around the engine bay to see if the idle changes. Just be careful.

 

[DaJackal]

No CEL. Did the keydance, no trouble codes (well, the standard 12 and 55 of course).

I thought that vacuum leaks would react exactly the opposite way? Like, the car would die if I do hit the brakes? Also vacuum leaks have usually caused high idle rpms, based on other topics I've read. Am I wrong here? Can vacuum leaks cause also this king of behaviour?

Edit: ISC checked, resistances are fine (50 kohm). TPS readings are about 15% idle, 70-75% WOT (I know, they're not OK). New TPS ordered, arrives hopefully on tuesday. I'll take the car to garage next friday, gonna do also the propane thing. Additional question: what do you think, do I need a new TB gasket? If I remember correct, the TPS can't be removed unless you take the whole TB off. How big is the chance that I break the gasket doing this? (I know, a new one doesn't cost much, I just doubt that getting it might take a lot of time 'cause Eclipse parts are not kept right on the shelf here in Finland.)

 

[gpsturbo]

Sounds like your timing is low. Get a timing light and check it. That usually happens when you come to a stop or push in the clutch to slow down. Check your CAS to see if it came loose, and go from there. If it is loose, you might have to reset the timing by the book. Also check all hoses and sensor plugs, (maf), they come loose and won't give a reading at certain rpms, etc.

 

[MikeL18]

Bump, any updates on this?

I'm having all the same symptoms. Car dies randomly, especially when cold. If I let it warm up to operating temperature it usually doesn't die. Sometimes it's difficult to start, I have to press the gas to rev it up so that it doesn't just die right away.

I have a CAI and whenever I turn on the A/C, I hear this loud suction noise from the intake. Could possibly be a vacuum leak?

I had a similar problem to this a while ago but that was fixed by replacing the Crankshaft Position Sensor.

 

[DaJackal]

Sorry for no updates in a while.

I fitted an ecu from an AT model and the car ran fine, this problem was gone. Now a month or two later I finally got my hands on a MT ecu. Swapped it in place and had no problems for weeks, now yesterday the car did this 3 times again. So, as you can see, no clear resolution for this has been discovered.

If this problem continues, I'm going to block off EGR and clean TB & intake manifold really well (seafoam, maybe?). Possibly I'll change some sensors too (cam & crank angle sensor, vss, iscm) though all if them should be fine according to multimeter measurements.

I'll do a full timing belt & water pump job next spring. The car performs well, so I don't think this is a bad problem.

Oh, and mod/chaged parts list since last year is:

AEM CAI, 55mm TB w/new (used) TPS & ISCM, header + 2.5" N1 style catback. Coolant temp sensor & front lambda sensor changed. New plug wires are on the way.

I'll tell you if I can make this go completely away. At the moment I think this has something to do with cooling system, because yesterday was the hottest day of the summer this far (30 degrees celsius in the shade).

 

[lq1driver]

check your coolant temp sensor for resistance

 

[spydergotboost]

well sounds like the ECU change was the right answer, you cant argue with months of not doing this after the change. Now the question is what keeps making the ecu bad. or possibly just throw the AT ECU back in to see if that helps again.