97 528I rough idling and an answer

[billB]

Finally my car (97 528I) gave me all the anwers I needed for my thread dated 8/17/2004. the answer is CHECK ENGINE with the follwing 8 codes/table 11 based on My Peak Reasearch manual and code tables:

C8: Precat O2 sensor no activity cyl 1-3
CA: O2 sensor control limit, cyl 1-3
CB: O2 sensor control limit, cyl 4-6

E3: O2 sensor adaption limit, cyl 1-3
E4: O2 sensor adaption limit, cyl 4-6

EE: Misfire detected, cyl #1
EF: Misfire detected, cyl #2
F0: Misfire detected, cyl #3

Although I have changed all 4 sensors I have to assume the precat ones are defective since they've good connection and can be mixed since they are all one of the same.

The big question becomes: is all this misfiring in cyl #1, #2, and #3 related to the O2 sensors or is it a different beast. The car has brand new dealer spark plugs and no codes of 01, 02, or 03 related to problems in the ignition coils, thanks God.

Any thoughts top gunners out there????????? Thank you

[billB]

I did some research on my own, came up with the following, and wish to post these answers in case someone out there gets a similar problem. Enjoy!

ENGINE APPEARS TO MISFIRE OR STUMBLE INTERMITINTLY
MODELS AFFECTED: 5 Series(E34), 7 series(E32), 8 series(E31) all equipped with ACS.
FAULT: Under certain specific conditions an apparent engine misfire or bucking may occur. This is not
an engine misfire.
CAUSE: Short (less than 100 milliseconds) fuel injection cut-off, as a result of MSR (engine drag torque
control) regulation. This is a normal ASC function that may occur under these conditions:
-The vehicle is equipped with ASC
-Vehicle speed between 45 and 60 MPH
-A rough road surface (e.g. potholes, railroad tracks)
-Light throttle(accelerator pedal only depressed 1/8)
-ASC not switched off.
SOLUTION: Replace the ASC control unit. no further diagnosis of the ABS/ASC system should be necessary.


for more in depth analysis check the following address http://www.bba-reman.com/bmwabsfaults.htm
Bill B

[Dirty_Tool]

Hey Bill,
sorry to take so long to reply but hopefully i can help here. 1st of all by looking at those faults I wouldnt think of an 02 sensor problem at all but more likely a fuel mixture problem possibly caused by a vacuum leak. The fact that the fault reads "02 adaptation limit " its saying that the fuel mixture is out of range so bad that the 02 sensors cannot compensate. A large vacuum leak could cause the misfire faults as well. I tell you what 1st comes to mind is that the evap hose which runs along the top of the intake manifold may be split. I would recommend removing the top plastic engine cover and inspecting it. There was actually a recall early on for this problem and an updated hose. Any idea if your car had this recall performed? Either way I would still recommend checking this 1st. Then continue normal vacuum leak troubleshooting along the rest of the intake manifold if the hose is not leaking. Unfortunately the OBD2 software that you are using does not specify whether the engine adaptions are too rich or too lean so the suggestions I am giving you will only apply if it is indeed lean (lean misfires are more common.)
Hopefully this helps, if I can help anymore please email me or PM me.
Good Luck,
DT

[billB]

Will this claim of lean mexture holds true even if the OBD 11 gives me a fault of C8 = precat O2 sensors, no activity???

Well put and phrased response and for sure will check the hose for leaks and let you know the outcome; many thanks.

[CosmosBlack]

Have you checked the oil separator?

[billB]

Dear CosmosBlack
Sorry I did not; and I cann't quite make the relationship with the oil separator since all the codes above are concentrated on the precats 2 sensors without activity (new ones though) If u wish u can elaborate further. Meanwhile DIRTY TOOLS had an excellent response and a good point worth checking (see his response above. He is saying the O2 sensors are paralyzed as a result of a huge leak . surely Will do the vacuum leak check tomorrow; and for the benefit of all member we will post the outcome.

By the way where is Beelzibub on this? Beelzibub you are missing all the fun troubleshooting this one?

regards
Bill

[billB]

Dirty Tools a year ago or two I had received a little card in the mail from BMW for a recall. Unfortunately I can not RECALL what that recall was about. Never bothered with it. I know shame on me!!!

[CosmosBlack]

Bill,
the oil separator...>>> separates oil and air intake.
If there is a leak or break, which is common, I have replaced it on both my E34 and E39, there will be a vacuum leak. Oil will get into the air intake as well. Sometimes you get a "whistling" sound from the engine.

Symptoms can include:
smoke from exhaust
sputtering, hesitant when accelerating
rough idling

symptoms get worse with time, eventually there will be loss of power and car will be sputtering and very rough running.

If I remember correctly, The error codes stated oil/air mixture too rich or lean. The left and right banks of the V8 were not firing consistently on the diagnostics.

[BeelZibub]

It's been a long time since I got my hands this dirty Bill, so I'd rather listen & learn on this one.

[billB]

Cosmo
Thanks buddy I'll look into the vacuum leak posted by dirty tools
and the oil separator if I can find!! of course I'll let u know ;much appreciated

For Beelzibub? Yah keep that white suite on while I get dirty with vacuums and oil separators. You know Cosmos comment let me think of BMW's resemblance to human bodies. OIL/Air separator doesn't that sounds like the blood/air bariers in the human lungs? just a crazy thought. see ya all soon.
regards
bill