Diagnostic check.

I've had a few flat spots here and there. It usually was air getting in somewhere i.e vacuum lines, throttle body tunning caps anda cracked oil vent pipe.

Yours is a different car that I'm not familar with but I'd guess that its going to be something simple rather than major good luck!

See your Dundee way have you ever been to any meets?

Edited by grahame34m5

i'm guessing cam/crank sensor gone belly up, air leaks would be a constant giving idle problems and the like, cam sensor not sending reading to ecu resulting in poor fuel and performance. HTH

the sensor shouldn't affect starting.it should advance ignition when running if its not advancing you have flat spot and high fuel consumption. (send my address after diagnostic!! )

I reckon it will be camshaft sensor around £75 iirc

(Only exact awswers will be considered.  )

whats that noise? Ohh that'll be the goal post moving then 

OK, dutch, I've got you down for camshaft sensor, and grahame34m5 for a
vacuum line.

Any advance on these two?

Crombers wrote: Oh and by the way, I diagnose the car myself using the laptop and interface

could you please tell us what software and connectors are required?

Recently had a similar issue with mine - all is now okay (I think!) - thank god

Proved to be the crank shaft censor - not sure how much they cost as they did it free - coz I just bought the car from them a week earlier

I was experiencing stalls (in an auto!) and then it would not turn over - if it would it would sound awfull and do about 1mph, then stall

Best of luck

And please tell us what software and connection you used to diagnose.

funnily enough a guy came into "my" work/shop a few days ago looking for cable to convert usb to rs232 (usb to serial) for his skyline, being the nosey bugger i am i enquired if he was doing a remap, he said it was just for diagnostics; so i'm intrigued for the details of the bm compatible version (not that i have the nous to be able to fiddle with it but i'd find it interesting to at least look at... )

Edited by stephenperry

you say a faultly MAFF would not show on diagnostics it did on mine, but this was ok. The pressure regulator valve was faulty which caused the MAFF to show up as the fault was before the maFF sensor..

Maybe a read this wrong!!!!

studyolic wrote: Well, the diagnostic check only showed up a faulty Lambda sensor (thats an O2 sensor?);   so I'm getting that done next week, and we'll see how it runs and whether the fuel consumption recovers.   Nothing else showed up, although I understand that a faulty MAF would not register. So I think my fiver is safe, unless I've missed a post above. Anyone claiming?

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There are a number of codes that relate to the Lambda Probe. They can be the heating elements, adaption limits etc. etc.

If one of them fails completely you will have a hard error code. However, a lazy or contaminated sensor will not flag on a pre-EOBD spec car.

When testing, the fuel trims should be investigated fully - this, in conjunction with a gas analyser will give the experienced tech an insight into what's actually happening... For example, you can have a car running 99%, emissions and fuel ratio spot on (Lambda Factor 0.99-1.01) but only because the DME has adapted its strategy to compensate for a fault (e.g. slight air leak). There are loads of adaptions that go on - Idle Control, Idle Fuelling, Part Load fuelling, Ignition timing (modern BeeEms have individual knock control and ignition monitoring/adaption on EACH cylinder).

When the Fault Codes are reset - the ADAPTIONS are not... So it's possible that you've got no error codes, that emissions are ok and it's still not right... Sometimes the adaption values adapt back reasonably quickly - more often, they don't.

As a quick example, I had a 523i that was running rich, and idle was useless... It was looked at by numerous people before I got to see it - (car was in Ennis, that's a long way from me). Different scanners were used - considered good equipment in the trade - Launch X431, Bosch KTS, Carmanscan II, Carsoft, Autodiagnos. All had cleared codes and some had reset adaptions - however, when checked, the ADAPTIONS were not reset...
A reset of adaptions immediately cured the idle. Then as the engine began to warm up I got a trouble code that was relevant - I replaced the relevant part and tested the car again... It still was not right... Adaptions had to be reset again.

Then it was 150 miles or so before the DME "learnt" its new values and finally when tested everything was within spec. Fuel trims, idle adaption etc. etc. It's a testament to the DME strategy that the car ran so well for so long without the owner realising there was a problem.

Fuel consumption was not 100% though - I felt that the Autobox was not changing either as smoothly as it should or exactly when it should. The EGS also adapts it's strategy based on driving style among other things. A reset of the adaptions for the Autobox (and a further 50 miles of driving) cured the car completely.

Sorry for being so longwinded - but I'm trying to get across that just replacing a faulty part does not necessarily fix a modern BMW/Mercedes/Audi. This is going to become more of a problem as time goes on.

OEM parts are now practically vital - I had an Audi A6 that failed the NCT on Emissions (only slightly). There were no fault codes, all values appeared fine - until you looked in detail (translation=hours). The cat was not at full strengh and a new one would have got the car through the NCT - but it was not what was wrong. It turned out to be a non OE part at fault...but it was Bosch, it was correct, but Audi had updated the part (with another Bosch item) and therefore the car was not running ideally. Fitting the new part and resetting those adaptions then cured the fault. Emissions perfect with Lambda Factor at 1.006.

Hope I've not got ye all frightened now ;)
Regards,
BMWcare
bmwcare@eircom.net