check engine light question

[nk530]

I recently aquired a 94 530 with 190,000 mi.
The car is truely unbelievable, with one small exception.
This problem, from what I've found on various forums, is fairly common.
I am hoping that if I can give a clearer explaination maybe someone can help me pinpoint it. Problem is as follows:
Car starts in cold (below freezing) weather just fine. I usually let it warm up about a minute before driving, but if I let it idle for longer than that the check engine light will come on. Some times it comes on, and as soon as I step on the gas it immediately goes off. Sometimes it comes on and won't go off until the car is up to temp. And occasionally it dies when the light comes on, or starts a really rough idle. All these symptoms go away when the car achieves its normal operating temp.

When the light comes on and goes immediately off I was able to get a 1214 code from a stomp test. When the light stays on for a while it is most likely a 1213.

o2 sensors are new, and I can't find a vacuum leak anywhere.
A mechanic who looked at it said there was a low signal from the ecu and the air mass meter, but I don't know how much I can trust the guy because of other things that the shop has screwed up.

let me know if any further info would help, and thanks

nate

[Rus]

Check the fuel pressure from the pump. I experienced similar symptoms with a weak fuel pump. The CEL would come on during prolonged idling, or shortly after start up (when the O2 sensor signals began to be processed and the computer detected a lean mixture). Idle was also rough/loping. The engine also hesitated when the accelerator was depressed. The pump was only providing about 20 psi of pressure instead of the 43.5 (M30 engine) that is required for normal engine operation. The specs for M50 and M60 engines call for 51 +/- 0.9 psi. Hope this helps.

[632 Regal]

http://www.bimmer.info/forum/forumdisplay.php?f=43

http://www.bimmer.info/forum/forumdisplay.php?f=14

[nk530]

I'll probably tear out the intake manifold this summer (no heated garage) until then I'll just make sure not to stop at any red lights

thanks all!