Erratic Idle/Stalling on '98ti

[bullmand]

I'm not 100% on this because I've never messed with it, but from what I've read you can't really test o2 sensors without an oscilloscope. Voltage readings alone won't tell you if the sensor is operating correctly. You might do a good thorough check of all your vacuum lines. It seems lately that vacuum issues are the root of all evil

[anthony318ti]

Originally Posted by bullmand

It seems lately that vacuum issues are the root of all evil

Hahaha nice one i know 100% know what you mean.

[danimal17]

You are right about that.

Thanks for that electrical troubleshooting manual, that'll be very handy. I have a pdf of the E36 Bentley manual, do you need that?

From what I remember, my O2 sensors are 4-wire. Maybe I'll buy one and swap them out sometime. Not right now though, my car has been running fine lately. Which is surprising since it's been bitter cold in northeast Ohio.

[anthony318ti]

Originally Posted by danimal17

You are right about that.

Thanks for that electrical troubleshooting manual, that'll be very handy. I have a pdf of the E36 Bentley manual, do you need that?

From what I remember, my O2 sensors are 4-wire. Maybe I'll buy one and swap them out sometime. Not right now though, my car has been running fine lately. Which is surprising since it's been bitter cold in northeast Ohio.

Hey no worries umm you can email it to me on anthony.titifanua@tds.com.fj let us know how you go with your car.

[danimal17]

Ok this stalling is becoming a regular thing now. Every morning on the way to work when I stop at a red light, with the engine warm, the car stalls. This will happen at about every red light now unless I keep tapping the gas pedal a little to prevent it. This is so frustrating. It looks like a guy had a similar problem here:

http://www.bimmerfest.com/forums/sho...d.php?t=115889

Looks like it may not have been resolved or at least wasn't posted.

Someone in the post mentioned a TDC sensor. The only thing I can think of that standing for is Top Dead Center, but top dead center sensor doesn't make sense. Anyone know what this might be?

[bullmand]

That bimmerfest thread really isn't very informative, is it? I can only surmise that a "TDC sensor" might be a crank position sensor or a camshaft position sensor. Either of those not working might cause the engine to not run, but I'm not sure it would happen in the manner that you're describing. They should also turn on the check engine light. Do you think the stall is related to the brake application or just the change in speed? Could it be vacuum related to the brake booster? Just making wild guesses here.

[danimal17]

No it doesn't seem brake related. It won't happen until the car is stopped or almost stopped, in neutral, with the brake on or off. It really does seem like a vacuum problem, but I've been over everything and just can't seem to pinpoint it.

[318ti_pt]

hey! check the spark cables and all the tubes that run air including PVC valve and tube and check all injection system too!

[marc]

How about trying to unplug the air flow meter while the idle is fluctuating, if it smooths out that would be it. The air boot would definately make it stall.

[anthony318ti]

IF you tried the above and have found no resolve try changing out the oil separator.

[danimal17]

Well I finally got a chance to spend some time on the car yesterday and here's what I did:

Changed PCV valve
Changed the intake bellow (between MAF and throttle body)
Rear brakes
oil change
Replaced main drive belt

I haven't driven much yet, but so far the car seems to be running much smoother. The stalling seems to be fixed and I really think it was the PCV valve. When I lifted the upper intake manifold, I could see some oil and dirt lining the inside of the lower manifold. Had no idea that they're supposed to be changed regularly. Anthony, you mentioned changing the oil separator. Is it called something else? Is it #12 flange here:
http://realoem.com/bmw/showparts.do?...69&hg=11&fg=40

Also, as you all probably know, the AC compressor belt must come off before taking the main drive belt off. I just replaced the drive belt and left the AC belt off in hopes of lightening the load on the engine. I haven't used the AC since getting the car b/c it didn't work when I got it and I just don't care for it enough to spend the money. My gas mileage went up a little. Any thoughts on this, anyone ever do it?

[anthony318ti]

PCV valve. A mate of mine did it in his 97 318is (run without the AC Belt) been running fine for about 5 months now. But i wouldn't recommend it. I think they designed the entire engine as an entire engine Drive Belt pulling to the right and AC belt pulling to the left although you could get away with little stress because of the awesome spring loaded tension pulleys.

As for your AC does your AC Compressor kick on when you turn it on and its not cooling or does it not turn on at all?

[danimal17]

My car stalled several times again today.... The idle is smoother, but now instead of stalling from a rough idle, the car just stalls from a smooth idle. One thing on my mind right now is the ICV. I noticed that it was making the normal buzzing noise with the key in the on position, but it wasn't a constant buzz. It was kind of alternating between a high and low buzz. Maybe it's nothing, I don't know.

I don't even know if the compressor kicks on or not, never even tried to troubleshoot the AC system.

[anthony318ti]

Originally Posted by danimal17

My car stalled several times again today.... The idle is smoother, but now instead of stalling from a rough idle, the car just stalls from a smooth idle. One thing on my mind right now is the ICV. I noticed that it was making the normal buzzing noise with the key in the on position, but it wasn't a constant buzz. It was kind of alternating between a high and low buzz. Maybe it's nothing, I don't know.

I don't even know if the compressor kicks on or not, never even tried to troubleshoot the AC system.

Thats weird but interesting. Never experienced that before. After it stalls when you start it again does it start up alright or does it have a little drag (cranks dead a few times) before it starts up?

[danimal17]

Sorry to keep jerking you around, but today the idle was smooth and there was no stalling. The only explanation I could think of is that it was above freezing outside today, but not yesterday.

To answer your question though, when it did stall, it did take a few dead cranks before starting back up.