Any E39 gurus out there?

[valvesprung]

My recent puchase of a '99 528 has left me grinning for days on end.

Unfortunately, it has begun to quickly and intermitently stumble @ idle. It only drops 50-100 rpm, so it's no big deal except that it shouldn't be happening. I removed the air box to take a look at everything and found that the problem stopped without it. When I blew slightly into the MAF and the car died, an odd thing for it to do. I worry that the MAF may be getting weak, but even though I am a technician, I am unfamiliar with BMWs. I removed the restrictor tube from the opening of the air box and the problem has gotten better, but not subsided.

Any great words of advice?

[Chip]

we have replaced the MAF on my wife's 97 528, then a year or so later replaced the idle regulating valve-
I will say that these cars have no shortage of electrical systems-
sometimes on the wife's car I'll take it to the stealer so they can diagnose the problem, then I fix it-

good luck



My recent puchase of a '99 528 has left me grinning for days on end.

Unfortunately, it has begun to quickly and intermitently stumble @ idle. It only drops 50-100 rpm, so it's no big deal except that it shouldn't be happening. I removed the air box to take a look at everything and found that the problem stopped without it. When I blew slightly into the MAF and the car died, an odd thing for it to do. I worry that the MAF may be getting weak, but even though I am a technician, I am unfamiliar with BMWs. I removed the restrictor tube from the opening of the air box and the problem has gotten better, but not subsided.

Any great words of advice?

[valvesprung]

I work @ a Volvo dealer, so I have connections to the local BMW dealer, but what might I expect for parts prices?

[winfred]

common problem on them is the cyclonic valve pops and leaks vacuum on the bottom of the intake, theres a oil drain that goes from it to the dipstick tube that rots off and leaks air and oil vapor too, you can usually hit it with some carb cleaner and effect the idle when you find the leak

[Jon K]

blowing on the maf will cause the car to stumble and or shut off. It's seeing the hot wire go colder (indicating air flow to the engine) the TPS not moving, and the RPM not changing, so its probably adding fuel because of a false positive on air cooling the hot wire maf... this will stall or bog it down.

[valvesprung]

Thanks I'll give it a shot.

[valvesprung]

Haven't had a chance to give it a shot, but are there any other words of wisdom?