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04 Ralliart idle and stall problems

Hey guys, I searched and found several threads about this, but no solution.

When I first start the car, it idles fine. When driving during warm up, when I push the clutch in (or shift to neutral) the idle will drop below 500 and back up, causing the AC blower to slow and the lights to dim. It also dies pretty often. After driving a while it doesn't seem as bad, but it still fluctuates pretty bad. The issue is worst when the engine is slowing from higher revs. I've read about the purge solenoid and blocked off the line to the throttle body with no change, and it happens in neutral so it's not a clutch issue, I've checked for vacuum leaks with an unlit propane torch, and there are no codes. Are there any other things to check?

You sure the check engine light isn't burnt out? Did you scan it for trouble codes?

Clean and reconnect your battery terminals, and check your alternator connections are clean.

And how you did block the purge solenoid lines?

Quote:

Originally Posted by CrAnSwIcK (Post 11836240)

The check engine light came on after I blocked the line between the purge valve and throttle body. I disconnected from the valve, bent it to crimp it ****, and put a zip tie on it to prevent a vacuum leak. This caused an evap code and no change in idle so I put it back. There are no codes currently. I ordered a new primary o2 sensor in case this one is getting lazy and slow to switch. It has 181,000 miles and is probably original so it can't hurt to try. I also ordered a larger throttle body just to eliminate the chance of the stepper motor binding or anything. I'll check the alternator connection, but the charging system is strong as long as the revs don't drop to 300 rpm. I'll report back when the parts get here this weekend.

It's probably the throttle body that's causing the problem. What throttle body are you using?

Right now it's the original throttle body. I have one from a 3.8l Galant on the way, though.

That will probably make it worse. It sounds like a bad purge solenoid. Those are a lot cheaper than a throttle body.

Quote:

Originally Posted by CrAnSwIcK (Post 11836291)

That will probably make it worse. It sounds like a bad purge solenoid. Those are a lot cheaper than a throttle body.

Just an update in case anyone stumbles across this thread: I replaced the upstream oxygen sensor (which runs through the floor pan under the passenger seat) and allowed the ECU to idle for 10 minutes after reconnecting the battery and then drove normally for a day. No change.

Then today I replaced the throttle body with the 63mm Galant unit and allowed the ECU to relearn again. So far this seems to have taken care of my issues. The idle drops back to 800-900 and stays there. As long as it stays this way then I'd call it a success. My theory is that the throttle body stepper motor was getting weak and having a hard time reaching the requested throttle %, but it wasn't bad enough to trigger a discrepancy between the accelerator pedal position sensor and the throttle position sensor and throw a check engine light and go into pump mode.

If it does come back, then it's some kind of learned behavior that I'll have to further diagnose. May look into the evap purge solenoid then, I'm just hesitant to change it since I've never had a code for it until I crimped the line between the solenoid and intake/ removed from the solenoid.

Anyway, hopefully it continues to run well and this year long issue will be solved.

Thank you.

The ECU is not tuned for that size throttle body, it will mess with your fuel trims...if it was the throttle body that caused the issue, then you should use the correct size...

Hi, I have a similar issue with my car, runs fine if I reset the ECU then I get the usual CEL and then at idle at running temps the car does not hold RPMs and stalls, I have just changed the front O2 sensor which was totally burnt out. but this problem is still there I am leaning towards a vacuum leak which I can not seem to find, I am hoping it is not a TPS which will mean a new TB which is in excess of $1kAUD.
the purge for the Evap? sorry not sure what this part is or where it is located. please enlighten me.

photobucket ****ed everyone and I lost all my pictures...so there are probably dead picture links all over the forum...

look on the dipstick side, kinda behind and underneath the intake manifold plenum...has two small hoses and an electrical connector.

I had exactly this maybe 2 years ago and cleaning out my throttle body worked for me. Pulled it out, cleaned it with a brush and solvent. Took a week for the ECU to re-learn how to idle but it’s great now. Just enough buildup formed to choke it at idle. Would have been around 230,000km at the time.

Switching to the new throttle body may have worked because it was clean.