Stall in the cold?

[booksat]

On cold mornings, about half the time, car stalls after backing down the 60 ft driveway into the street and putting the car in drive.
Otherwise, the engine purrs.
Doesn't happen again later in the day.
No vacuum leak.

Any ideas?

[jclausen]

Cold start valve or sender for valve

[richardodn]

Cold start valve isn't in play here. Even if the car were equipped with one, that's shut off within a few seconds. It's a cold START valve, not a cold RUN valve.

When the engine is cold, it does require fuel enrichment at idle. As soon as you pop it into drive, give it a sudden load and it dies. I would check the ECU's temp sensor (2 pin one, typically blue or white) and the throttle position switch.

[booksat]

Cold start valve isn't in play here. Even if the car were equipped with one, that's shut off within a few seconds. It's a cold START valve, not a cold RUN valve.

When the engine is cold, it does require fuel enrichment at idle. As soon as you pop it into drive, give it a sudden load and it dies. I would check the ECU's temp sensor (2 pin one, typically blue or white) and the throttle position switch.

Thanks!!

Can you help me further here (my mechanical knowledge is limited).
-I'd assume that this stall only happens when it's cold out and only after sitting overnight would be clues. Also remembering now that when it does stall, it can be hard to start again..but then when it does, it's fine for the rest of the day.
- Question: Does the stall only happening in the cold weather point more to the ECU temp sensor or to the throttle position switch?

Questions:

A. Trying to tackle this problem, mechanic did the following, which didn't help. I'm wondering if these were reasonable steps, especially given that the car ran and idled perfectly. Replaced spark plugs, fuel filter, fuel regulator, air filter, He also found a small leak from the valve cover to spark plugs. So, the valve cover gasket was also changed.

B. Less than a week after the work was done the car ran rough and was stalling. Mechanic found that the AFM was soaked with oil. While he suspected that this might have part of the original problem, isn't more likely that he soaked the AFM while doing the other work? The car wouldn't be idling and running smoothly with oil building up in the AFM, would it?

[richardodn]

Does the stall only happening in the cold weather point more to the ECU temp sensor or to the throttle position switch?

In general, the TPS is more likely to fail due to oil entering the switch. It's located below the throttle body and oil can seep down into it. Internally it's only two microswitches; 1 for idle and 1 for wide open throttle. Oil enters the intake through the crankcase ventilation hose. After time, the whole tract from the AFM to the intake valves can get covered in oil. Whether yours is excessive or not is an indication of how well the rings are sealing the pistons. To check that have a compression and leak down tests done. They'll give you a good picture of the health of the motor. The temp sensor can be tested, but that's cheap enough to just replace. The TPS can be tested on the car. If you do find that failing, you can get away from replacing it by drilling some small (1/8" is fine) holes in the plastic cover to allow oil to drain out. Then use carb or brake cleaner to spray in the cavity to flush it out.

Trying to tackle this problem, mechanic did the following, which didn't help. I'm wondering if these were reasonable steps, especially given that the car ran and idled perfectly. Replaced spark plugs, fuel filter, fuel regulator, air filter, He also found a small leak from the valve cover to spark plugs. So, the valve cover gasket was also changed.

Not really. A good mechanic would have homed in on the association with cold. It sounds like he was just swapping parts. In particular, I hope he did a fuel pressure test before replacing the fuel pressure regulator and found an issue. If he didn't, I wouldn't go back to him.

Less than a week after the work was done the car ran rough and was stalling. Mechanic found that the AFM was soaked with oil. While he suspected that this might have part of the original problem, isn't more likely that he soaked the AFM while doing the other work? The car wouldn't be idling and running smoothly with oil building up in the AFM, would it?

Oil in the AFM usually doesn't do a thing on these cars. This is an early system and it measure's air by how much a mechanical vane deflects. Later types with mass air flow (MAF) meters would be affected. And as I said before, oil ends up covering the intake tract. As for the rough running and stalling, he left a vacuum leak somewhere when he first had the car. It could have been something as trivial as a loose oil cap.

To be honest, I'd recommend finding a good independent shop that knows BMWs. They may cost a bit more up front, but you won't keep having to bring it back.

[booksat]

To be honest, I'd recommend finding a good independent shop that knows BMWs. They may cost a bit more up front, but you won't keep having to bring it back.

Again, thanks so much!
Unfortunately you may be right about finding a new shop. Would hate to leave this great German only shop, but the new BMW guy's experience doesn't extend deeply into E30s, as did the mechanic who had left.

[richardodn]

Again, thanks so much!
Unfortunately you may be right about finding a new shop. Would hate to leave this great German only shop, but the new BMW guy's experience doesn't extend deeply into E30s, as did the mechanic who had left.

That's a pity. Of course the only way you gain experience is by working on them, but it shouldn't have to be on your dime.