horrible s50 idle, please read, I am sick of this

[gregslow318i]

o2 sensor? what about coolant temp? how new are they? also fuel injectors/ fuel filter?

[BMW_TUNER]

Any chance that there is a fault in the wiring to the alternator/starter. It may be load cycle that you are getting due to an intermitent loss of continuity at the alternator.

[sharky]

is your throttle cable adjusted correctly, you will get a rpm surge and drop from that.

[Farbin Kaiber]

Can you test another DME? Is there anyone that could help you with testing another set of sensors from a known working engine setup?

[VacMan]

Agree with Farbin. I'd be swapping in another DME if you're 100% certain you have no vacuum leaks.

[Farbin Kaiber]

Agree with Farbin. I'd be swapping in another DME if you're 100% certain you have no vacuum leaks.

And, you are sure that way back in the beginning that ICV you installed is in known, good working order. And not backwards.

[Bimmer335is]

Check your Brake Booster as well for any leaks, that's where I found mine. I also had a bad DME. So check the both of those.

[Jason89i]

its hard to diagnose over the internet without any knows / unknowns ruled out. need more hard data.

how much vacuume are you pulling? go buy a vacuume gauge and test at idle.
after clearing codes, do you still get "A1" ?
is there any slack in your t-body?
does your throttle plate return to set screw naturally?

cheers, jason

[rede30]

I finally spent some time on this. I grabbed the nuked wire harness and traced the melted wires and saw where they went and what they touched. I saw that a ground wire had melted in a spot where the green wire touched it and that ground wire grounded the TPS, intake air temp sensor, and the engine coolant temp sensor. I am not that great with how wiring works but I feel like when I had a wire melt in my harness, if a ground wire got power it would do damage to the sensors. So I ordered the three new sensors that got powah to their ground.

my tps did check out when I tested it with teh bentley tests. I have not checked my Intake Air sensor, it was only $20 for a new one. Can a bad TPS or Air intake sensor cause a surging idle?

[Farbin Kaiber]

Prolly not on the two sensors, prolly yes on the three.

[rede30]

Prolly not on the two sensors, prolly yes on the three.

wait, what? do yo mean if all three are bad my idle might surge? Or that they all three would go bad if their ground got power?

[Farbin Kaiber]

No, that the issue is more likely related to the three sensors you said you were replacing opposed to the two you asked about potential for causing issues. It may only be one of those three, but who knows without pulling them and testing them by the book.

[r4esh]

With the intake off, go through the ETM test. Get a multimeter and test each sensor one by one... tedious, but it will eliminate the questions... did for me - i determined I had a failed cam sensor. Replaced it and she purred.

[Farbin Kaiber]

^ He said he already ordered all three that were potentially fried via a ground short in the harness.

[sushipower]

A bad TPS or Air intake sensor can cause rough idle. The question is what caused the short? Did you make sure "ALL" ground cables are connected (including the engine block)? Hope you find the cause.