Strange idle behavior under specific conditions.

[RADRACR]

Firstly, this is not about the tired discussion of the random stall that all S54s seem to have.

1) When cold (within 5 minutes) engine drops RPMs and nearly stalls at the moment the accelerator is pressed. 90% consistent every morning after waiting for the community gate to open to drive out. After that one occurrence, the rest of the drive is fine. This is different than the more common issue of randomly stalling when cold unrelated to accelerator.

2) After turning on A/C, idle becomes irregular. Very subtle. Can barely see the tach move but I have aftermarket exhaust and can hear it. The issue remains after turning off A/C. But starting the car WITHOUT A/C is fine until I turn A/C on again.

I've been reading about the ICV (idle control valve)? What do you think?

[yousefnjr]

Any codes?

[RADRACR]

I don't have a device to check. No CEL.

[yousefnjr]

Might be able to have Autozone etc. check codes for you. I had a similar situation a few months ago with a rough idle and near-stalls, and I had codes for over/under voltages across several control modules. No CEL either (except the couple times it actually stalled...). Turned out to be my voltage regulator on the alternator, around 60k miles at the time IIRC.

Could be something similar, could be totally different, codes are a good place to start GL

[F360C]

Originally Posted by yousefnjr

Might be able to have Autozone etc. check codes for you. I had a similar situation a few months ago with a rough idle and near-stalls, and I had codes for over/under voltages across several control modules. No CEL either (except the couple times it actually stalled...). Turned out to be my voltage regulator on the alternator, around 60k miles at the time IIRC.

Could be something similar, could be totally different, codes are a good place to start GL

I had some weird idle issues with my car also... replaced the voltage regulator on the back of the alternator and all is fine now. You can get the part off ebay for $60 and it takes about an hour to swap out.

Other causes could your MAF, O2 sensors, very dirty airfilter or maye a vacuum leak somewhere in the engine bay. Grab a beer, flash light and have a good solid look around the engine bay. Gently move/tug lines and wires/hoses/lines to make sure everything is still connected.

[angelr]

Originally Posted by F360C

I had some weird idle issues with my car also... replaced the voltage regulator on the back of the alternator and all is fine now. You can get the part off ebay for $60 and it takes about an hour to swap out.

Other causes could your MAF, O2 sensors, very dirty airfilter or maye a vacuum leak somewhere in the engine bay. Grab a beer, flash light and have a good solid look around the engine bay. Gently move/tug lines and wires/hoses/lines to make sure everything is still connected.

Would you happen to have that part number handy?

[F360C]

Originally Posted by angelr

Would you happen to have that part number handy?

http://www.ebay.com/itm/NEW-VALEO-OE...STRK:MERFB:IID

[yousefnjr]

^^ pretty sure I bought the same one too, sure as hell beats buying a new whole alternator

[angelr]

Originally Posted by F360C

http://www.ebay.com/itm/NEW-VALEO-OE...STRK:MERFB:IID

Cheers!

[RADRACR]

Now my ABS, Brake, and DSC lights are coming on and off intermittently. Radio cuts in and out. Certainly seems electrical related. Will try this voltage regulator.

[StickMon]

How old is your battery?

[RADRACR]

Originally Posted by StickMon

How old is your battery?

Original!

[StickMon]

My car got similarly wacky and ultimately went into limp mode claiming the TPSs were broke.
Replaced 5 year old battery. Problem solved.

[RADRACR]

1) Replaced OEM battery with Napa 9848. No effect to my issue but I'm not upset about it as it needed replacing regardless.

2) Changed Voltage Regulator. Drove to and from work today in 100 degrees with A/C on -- so far so good. But goddamn was it a PITA getting that alternator in and out. Evidently those bolts are only cosmetic.

I imagine lots of folks replace the whole alternator when only the cheap plastic regulator is bad. It would seem the alternator itself is a more robust piece of equipment.

Does not solve issue #1 in my OP. ICV still?

Anyway, thanks A TON to this forum. Saved my ass.

[StickMon]

Originally Posted by RADRACR

... Evidently those bolts are only cosmetic. ...

After finally prying mine out, I filed it down a little bit to make it easier to get back in.
Still had to pound it in with a mallet. Makes it fun to get the holes lined up so the bolt will go through.

[Finnegan]

I'm pre-ordering one of these voltage regulators. It's only a matter of time.