$775 Oxygen sensor in NC

[Jon K]

I know Could be a ton of **** I could diagnose but I am not there.

[Tiger]

V8 are pretty reliable car... I owned it for 8 years now... Vacuum leak can be the intake gasket (very common) and the idle control valve that is underneath that...

MAF is a possibility if it shoot out that MAF or O2 engine code... but easily verified by testing the components.

Other than that... I never had any problem.

[Jon K]

Question for the gurus - if I have her unplug the MAF - it should run better, if the MAF is misreading, right?

[bubba966]

Question for the gurus - if I have her unplug the MAF - it should run better, if the MAF is misreading, right?

That's what I've heard as well. But don't run it for extended periods with the MAF disconnected, do that only for diagnosing a MAF problem.

And yeah, have her take it to Korman.They know E34's better, and charge rather reasonable rates looking at the receipts of stuff they did to my car before I bought it.

OEM O2's for the 530 list at $202/each. Even if they wanted 25% over list (seems that most dealers charge 20+% over list) that'd make $500 for a pair of O2's, and it certainly should cost $275 to install a pair of O2's. I've not seen the underneath of a 530 yet, but I'd imagine it's like my 540. Which would make it insanely easy to change them out.

[Ferret]

Question for the gurus - if I have her unplug the MAF - it should run better, if the MAF is misreading, right?

Correct, but it will take both the MAF and the O2 sensors (afaik) out of play... it wont give you a positive diagnosis of the exact component but it'll tell you there's something wrong with the metering rather than a mechanical fault.

On the uk E39 boards they constantly bitch about BMW dealers diagnosing O2 sensors because of a vaccuum leak or MAF failure - the ECU will throw an O2 code whenever there's a metering fault somewhere. The only exception to this is when the MAF fails electrically, a la unplugged MAF.

[repenttokyo]

Try this: unplug the battery long enough to wipe the memory in the computer. Replug the battery and start the car. The car will run in closed loop for the first 5-10 minutes (don't know how long it lasts on the e34) and won't be reading any data from the MAF. If it runs properly....could be an indication.

I used to do this on Ford V8's to run in closed loop when we suspected a MAF or other sensor problem.

[Jon K]

I have the dealer unplugging the MAF and running it and then pulling O2s and seeing if they're super fouled or not.

Why am I telling the dealer how to fix this? Ugh.

[M20Turbo]

[QUOTE=bubba966]Jon, send your sister here http://www.kormanfastbmw.com/

Hey Jon.... Ray Korman in Greensboro is where I had my engine built (I know, I bought and did not build) in 2001, and I live in New Mexico. Ray has been very helpful to me over the years. I know it's frustrating to fix/diagnose anything form long distance.

[DanDombrowski]

When its not reading sensor data, I'm pretty sure thats considered open loop.

Closed loop is when it does modify based on output data.

[Jon K]

The Dealer is saying they're getting an "open circuit" fault on the one O2 sensor - I am letting them replace it (For like $300 ugh). I'll post when it's done...