Confusing Errors!!

[masbury]

1990 750i German National car. DC02833

The car has no cats. In fact, I believe it shipped new sans cats. It also does not have O2 sensors. Attached pics of where (I think cats and O2 sensors go). It looks factory, if some muffler shop had deleted them, they would have used plain Jane straight pipe, and would have welded in O2 bungs like my 850.

So, here's the dilemma - when I ran the codes, I got the error about one bank being as lean as possible while the other as rich as possible. Same error I got on my 850 when the O2 sensor connectors were reversed.

Since there is no O2 harness and no way to put in either sensors or harnesses, is this actually running this way, or is it running with both banks correct and just complaining.

Thank you

Edit: Forgot the pics. Can't add after the fact.

[shogun]

Prod.date 1990-01-17 and L801 National version Germany/Austria should have been delivered with cat system or at least CATALYZER PREPARATION CONVENTIONAL EXHAUST TECHNIQUE, http://www.realoem.com/bmw/enUS/part...BMW-750i&mg=18 That means the Motronic and the wiring is there for O2 sensors. But how that works w/o installed sensors and you get a warning I have no idea.
Here is how you can test the Motronic for the signals
oxy sensor testing at the DME/MOTRONIC in E-box
http://www.bimmerboard.com/forums/posts/622383/
unfortunately the imageshack pics do not work anymore, but I uploaded it again below.

Maybe you check once more, even if there is no cat, maybe they installed the O2 sensors in the normal exhaust, on the E32 there are anyway only O2 sensors which check what comes out of the engine and not what comes out of the cats.

[masbury]

shogun;

I looked at the exhaust all the way to where the exhaust header flanges bolt to the head pipe (springs on bolts) as well as clear back to the resonator and there is neither cats nor O2 sensors. I've attached the pics of the pipe where the cats and O2 sensors "should" be. To me, these look original to the car.
20170522_104327.jpg20170522_104338.jpg

I know the car was not "Federalized" when it was imported in 1994. The original owner was a German Air Force pilot going to a duty assignment in Texas for NATO, so customs just "waved" the car through, and since I have all the service records since new, there is no mention of removing the cats.

I don't have a problem with the "no cats" part, it's just worrisome that the DME is complaining about the O2 sensors that don't exist. Not to mention the "How is this working?" part. The car runs very well. Idles totally smooth, accelerates like a stock V12 should.

I have not yet pulled the plugs, so cannot tell about mixture conditions based on banks. I will test the DME as soon as I can and post up results.

If you have any more ideas or if you think these pipes are not original, I would appreciate your feedback.

Thanks

[whiskychaser]

IIRC, some cars had the facility to use O2 sensors and cats but they were not fitted when the car left the factory. There is a term for this but I've only seen it in German and can't remember it. I don't see it mentioned in the VIN decoder but perhaps Shogun can remind me anyway

Even if the car does have O2 sensors and they are plugged in and tucked away somewhere, they will not be reading much of anything. So it is doubtful the rich/lean mixture comes from them. Maybe confirm what code or data you are getting?

[masbury]

Gentlemen;

I checked for a voltage on (I think) the right pins and got no voltage on either pair. I am adding pics of the errors from GT1 DISV44. As I said in my first post, these are the same errors I had on my 850 when the O2 sensor connectors were reversed.

I'm at a total loss. I see no O2 sensors nor cats throughout the whole length of the exhaust system, from the headers to the tail pipes, yet I can't figure out what the errors mean or their origin.

DME 1-6 Diag.pdfDME 1-6 Errors.pdfDME 7-12 Diag.pdfDME 7-12 Errors.pdf

Apologies for the sideways view. That seems to be the way that GT1 wants to print screen shots.

Help!

[shogun]

Not refering to the fault codes you got there now: Also check the 2 MAF = hot-wire sensor, M70 have mass airflow meters. Here is how to test http://bmwe32.masscom.net/sean750/MA...leshooting.htm
You can swap the MAF from right to left (bracket does not fit, but does not matter for a test), if the fault switches to the other side, = bingo, 1 MAF defective.
Also pull on the wire loom close to where the cable loom is plugged into the MAF, the plug breaks when old and then the pins have no contact anymore = if you can pull out the plug without releasing the lock mechanism, the plug is broken internally.
I have some in stock new, in case you cannot get them locally. Part number for spare plug is difficult to find, here my info http://www.bimmerboard.com/forums/posts/697579/
http://www.bimmerboard.com/forums/posts/1239402/
Also check on the intakes close to the firewall, on each side bank there is a plug connection for air intake temperature, check if that is connected. http://bmwe32.masscom.net/sean750/sp...enumIntake.jpg

[whiskychaser]

My E34 left the factory without cats/O2 sensors because of where it was built. I have DIS v44 too and never had any readings like that. The strange thing is that it appears to have happened only 3 times. So I'd be inclined to follow Shogun's fault finding steps though I have to say I am curious what the fault codes are