2001 325ti: intermittent loss of power, slow starting, wavering tacho reading in the midrange when engine loaded up but with steady engine speed, poor idle. No CEL, P0335 crank position sensor A circuit malfunction and P0161 O2 sensor heater circuit malfunction bank 2 sensor 2.


Changed the crank sensor and P0335 intermittently returns. Not done O2 yet but wouldn't think a post cat sensor's heater would cause any running problems? I may need to go over the wiring but tempted to change the cam sensor next.


2003 M3: engine runs perfect but CEL after first decent run appeared when engine restarted after refuelling (cap is tight). Unfortunately the OBD port supplies power but won't connect with three different fault code readers. Perhaps the CEL and this are related? I did use a tyre compressor in the 12V socket (didn't blow it but will check) but it did a 10 mile trip after and it was only when restarted after fuel that the CEL came on.

 

Did you use an OEM CPS ?

M3....wouldnt suprise if it was a fuel trim fault...

 

No just used a crank pos sensor I could get quickly. That may be a mistake but from searching it seems that P0335 often persists after genuine replacement and can also be cam sensors, fuel pump, swapathon. I will start checking the wiring loom etc.

The M3 can wait, just want to try to get the 325ti going for this weekend to drift again.

 

Hmmm, certainly sounds crank sensor related from the symptoms. But the Inlet cam sensor does give some grief - longer cranking, and low speed performance issues and randomness (as it affects the cam timing), but IIRC it should not affect the tacho reading. Exhaust cam sensor doesn't do much apart from regulate the VANOS.

I think I have ECU pin outs for these somewhere if you wish to test the wiring. Or at least for the saloon version, which should be the same. Its probably online anyway.

Oxygen sensor heater circuit is usually the sensor and less often the wiring (unless it melted on the exhaust)...Easily checked by swapping the connectors over on the bank 2 sensor with the bank 1 sensor...Clear codes, Start engine, recheck codes, if the fault moves to Bank 1, its the sensor. My memory is fuzzy on if the early M54 DME uses the post cat sensor for aging/correction of the upstream sensor, but being 2001 model year I seriously doubt it, so all its there for is to monitor the cat efficiency.


As for the M3 OBD socket...it quite common for these not wanting to talk to generic code readers. Of course, make sure none of the female pins haven't been pushed back into the connector.

CEL on instantly after start-up usually means something has gone open circuit or short circuit. Or a bad battery with excessive voltage drop whilst cranking will cause all sorts of random codes to get logged.

 

I would go for OEM crank sensor.... Aftermarket ones are really poor,and can give some trouble right from the off.

Do you have a scope to monitor the sensor signal ?

 

As I've got my laptop fired up & I'm logged into a well known data site, I had a quick look.. There is a TSB on the compact which might be worth checking.

"crankcase breather pipe corroded, allowing additional air to be drawn in"

There is a modified breather pipe for the 'fix'

I think you might have a few other niggles with it, but it might be worth a check of that (in regards to your idle/power loss) as it can cause.. "poor idle, lean mixture, limp mode, loss of power, O2 sensor faults" according to a well known data provider.

The rev counter does sound like the CAS, but as you say CPS can cause probs. you might have been unlucky with a crappy replacement, OE spec is preferable. See if you can follow the wiring too, there was something I read online the other day about the wiring for the CAS running tight under part of the head somewhere, think it was front of engine as wiring comes up and is tight under something causing damage to the loom.

 

Thanks all. Somewhere I have a Labjack, not had to use for 10 years. Not easy with the car being on a farm 20 miles away near the track and trying to work out what stuff to take and work in sheds.

M3 CEL extinguished itself, will see if comes back. Ordered some BMW diagnostic stuff, INPA cable etc.

 

Adaption values (additive and multiplicative) for the fuel trim in the live data will quickly rule that out - the closer to zero, the better.

 

Checked the loom and was OK. The original O ring was a bit fat to get the sensor located deep enough, in the end with a slimmer O ring it all seems to work but given it was intermittent with the original and aftermarket sensor will have to see.

Meanwhile...

IMG-20150312-WA0001 by jcsbanks, on Flickr

Trying to work out the spacers required and whether the track rod ends need to be modified for so much lock

 

Borrowed 25mm spacers and different offset front wheels. Mad farmer co driver who used to post here is going to shorten the tie rods to bring the toe back as whilst there is thread spare they are likely to bottom out.

INPA is reading the M3. Stored but repeated VANOS faults. Looks like easy DIY of new bolts VANOS gasket but few hundred quid on solenoids. Lots of threads on it. A known E46 weak point.