M20 Stalling When Warm/ Operating Temperature

[KIRIEIW]

I actually did a timing belt job for a buddy just last week, along with a few other things and the breather hose was one of them. He didn't have a new breather hose to put back on the car and he chanced it and drove it home with NO hose attached. Ran great for him, in fact a lot of 2002 guys just put a little air filter deal on the valve cover where the breather hose nipple is with no issues. With that being said, I got a new breather hose from work for him the next day and installed it for him. I don't think vacuum leaks from the Valvetrain area effect the car much, if at all that breather hose is there just to help with emissions (I hope so anyways otherwise I'm looking like a dummy here).

I just installed the new coolant temp sensor with no change, looks like it's time to test the TPS. It does click, so I need to test its resistance with the specs the Bentley calls for.


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[KIRIEIW]

M20 Stalling When Warm/ Operating Temperature

TPS is working and in spec


Edit: decided to just take the throttle body off and clean it. Was pretty clean, light amount of oil but I've seen much worse on m20's. I was able to instal my new throttle body gasket though so that was nice. Crappy pic of before I cleaned it.



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[KIRIEIW]

I found this kinda interesting (the first line) when I was going threw the records. I guess the car was brought into the dealership and they replaced the fuel pump AND its connector. I'll take a look at it but like I've said many time's, the car has a really smooth idle when you first start it, then a couple minutes later it'll become rougher until it finally start's stalling on you when you tap the throttle pedal, or come to a complete stop at a light (basically whenever you bring the car back to idle from when then engine was just being rev'd). The car still has a hesitant idle that you can hear when warm, but usually won't stall until you tap the throttle pedal... Occasionally will stall on its own at idle.




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[Bullet Ride]

That's a good catch, there could be a botched solder that worked ok for a while but is now cracked or separating.

[Jdbush2010]

I found this kinda interesting (the first line) when I was going threw the records. I guess the car was brought into the dealership and they replaced the fuel pump AND its connector. I'll take a look at it but like I've said many time's, the car has a really smooth idle when you first start it, then a couple minutes later it'll become rougher until it finally start's stalling on you when you tap the throttle pedal, or come to a complete stop at a light (basically whenever you bring the car back to idle from when then engine was just being rev'd). The car still has a hesitant idle that you can hear when warm, but usually won't stall until you tap the throttle pedal... Occasionally will stall on its own at idle.




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These were my exact symptoms, not dying but idling right around 450-500. Except I've gotten it kinda controlled now with the crankshaft sensor. It still wants to idle rough but I'm getting on the upper side of the fight. I don't know if you checked that or not

[KIRIEIW]

Good news! I swapped out the ICV today and it hasn't stalled yet. I was messing around in the morning today and the car would run with the old one un plugged at operating temp, but as soon as you re connected the plug it would die right away. After that test, I figured it would be worth swapping it out for another one and the car's been running fine *Cross fingers* since.

The other good news was I got it smog'd right after and it passed with great numbers! I should have just swapped the ICV from the very beginning, I just found it un likely to be the issue because the old one in the car would buzz as soon as the ignition was turned ON. To future readers, don't assume your ICV work's because it's buzzing with the key ON, your best bet is to swap it for another used one or at very least check if the flap is binding (which mine wasn't, but wasn't very smooth to turn).

Will update the thread if this permanently fixed the problem or not. Thanks everyone for the suggestions and help.

[goldenbb]

You can usually just clean an ICV and it will work again. I found that the TPS (throttle position switch) can test good and still not work--the solder joints get old and lose conductivity and even though they look ok, they are not. I have fixed them by just adding new solder.

[KIRIEIW]

You can usually just clean an ICV and it will work again. I found that the TPS (throttle position switch) can test good and still not work--the solder joints get old and lose conductivity and even though they look ok, they are not. I have fixed them by just adding new solder.

Well I cleaned the original ICV and the problem remained, since installing this used ICV though it hasn't acted up. Like I said though, I still have my fingers crossed this fixed the problem. I've only driven it 10 miles since, but before I couldn't even drive it a half mile with out getting stranded.

Hmm interesting on the TPS, I'd think if the solder joints broke it would test faulty.


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[Som]

The WOT connections on my TPS had cracked at the solder points. It tested faulty/good intermittently. I just resoldered with a little added solder and the problem was fixed. Never really looked at the idle switch side, though, to see if the same problem could exist there, but I don't see why not.

I've read that you should be able to clean ICVs, but it's not something I've looked at, which is why I figured trying a different one would help. If it ends up working, I'd wonder if it had something to do with the connector/wiring in that area. Maybe it wasn't plugged in right the first time around? I haven't really been able to find a good description of what actually fails when they "go bad". According to this wiki (http://www.e30zone.net/e30zonewiki/index.php/Intake), it's "rare that they fail completely".

Problem fixed is a problem fixed, though. :) Glad it's working out!

Som

[KIRIEIW]

Drove it to work today and still no stalling


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[mazzo]

Is your e30 capable to do stomp test? Is yes, what is the code?

[KIRIEIW]

M20 Stalling When Warm/ Operating Temperature

Is your e30 capable to do stomp test? Is yes, what is the code?

You can only a stop test if the check engine light is currently on, or was on long enough to store a code which wasn't the case for me. The check engine light would only flash for a split second.


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[KIRIEIW]

Ok well the car still hasn't stalled, but it's still idling low. In fact, it's gotten even lower over the past couple days. Once warm, it idles at around 475-500RPM's. Clicking the AC button doesn't help much, maybe brings it up to exactly 500RPM if even that. I still can't get over the fact how well this thing idles and sounds when its warming up. Sounds just like a normal M20 should and I've owned 4x m20 cars, currently owning two. As soon as it's up to operating temp it still idles, but you can hear it's not running happy (of course plus you can see it's idling on the low side via the tach.)

Either the stalling problem has been fixed but the low idle issue remains, or the stalling issue has just went away temporally. Either way I'm even more stumped then before, I'll most likely try another idle control valve just because since swapping it out the stalling issue went away, but doubt it will help. I'm wondering if my rear main seal leak can cause a big enough vacuum leak to cause low idle issues. It did pass smog last Saturday with good numbers though..

I'm just about forced to drive this car around now as my temporary daily, my other car just started whining and clunking from the rear end TODAY. At least work is only a few miles away.

[KIRIEIW]

Well my tach was reading 250RPM's today at idle, now we all know that's not possible especially when the idle sounds the same as it did a few days ago. The SI board is failing is my guess, but that's the least of my worries. I've been driving the car everyday since replacing the ICV and it still hasn't stalled on my once which is awesome. It idles somewhat better, but it's still has that "unhappy idle" sound once the car gets to operating temp. Since I can't really rely on the tech for an accurate idle RPM reading, I'll just take a guess that it's probably idling around 600. Clocking the AC button doesn't really bump up the idle much, but the extra maybe 50RPM's it gives the car (yes I know it should bump up the idle up around 300RPM with the AC switch on) does help.

[mazzo]

Can you also check your distributor cap and rotor?