Hello, I wonder if anyone can shed some light on this little problem my car had yesterday. The AA man had to toe me away. I was driving my 318i up a hill doing 30mph but it seemed like it wasn't as powerful the engine was warm by now too. I came to the junction and it ticked over ok, then I booted it to overtake, bout 4000rpm and I heard a backfire and it cut out.

I the AA man came, did some checks in the fuse box with his test equipment, turned it over a few times, fuel was there etc. But he said it seemed like it was firing at the wrong time. Could be a CAM or CRANK sensor. I was toed to my local Bosch specialist and they said the same thing.

I've never had anything go wrong with this until now, does anyone else agree? Or had this before? All thoughts on the matter greatly appreciated.

I think you really need to get it to someone who can plug into the OBD and interrogate the ECU for error codes - if it was crank sensor, etc, it should show up and take some of the guess work out of it. You don't really want to start buying new sensors at £50 a throw if they are not at fault.

Incidentally, my crank sensor went on my 3.0 M3, and my friends 323i at similar times. Both started off with a slight hesitation, followed by stalling at idle, and then my friend's car just cut out on him. But there was that gradual degredation first.

Good luck though.

Ok, its been to my local Bosch specialist, they couldn't get the diagnostics to communicate. they said they were almost certain it was the carnk or cam sensor. They changed em and it still wouln't start. So they arnt chargin for fitting the sensors, they are sending them back. They are getting some guy with a BMW ECU interrogater to find out whats the problem. Anyone got any ideas? I'm getting worried now. Thought it was something simple. I hope its not the ECU. I was under the impression it could only be airflow meter, oxygen sensor and idle/throttle valve. But I think if any of these goes it has got a limp home factory default value.

Someone please shed some light, to prevent me crying when they ring with some bad news.

cheers

Brendan

Well Zim, it doesn't sound good. I'm sure someone will jump in a correct me if I'm wrong, but from how you described it going pop, if it was AFM, Lambda or Idle Valve, it would still run, but probably like a bag of nails - super lumpy or rich or something. These would not prevent it starting or running, or cut out like it did.

The fact that they could not communicate with the ECU I guess could be one of 2 things. Either they don't have the right equpiment (possible, but unlikely if it was Bosch) or the ECU has gone to that great big scrapyard in the sky.

Get the tissues ready to wipe your eyes....

Well 4 days later and £399.97 shorter and we've cracked it. We had the BMW diagnostics on it today. There were zero amount of fault codes stored in the ECU and everything was running ok according to that!

So they gave a quick call to a BMW specialist in Tamworth, they cracked it! Without looking they said check the dual mass flywheel that comes off the cranck. 80% of E36 M43 engines have this problem at some point in their life. There is a woodrough key in the drive for the flywheel. This broke but the bolt that holds it tight against the shaft, held the timing or dual mass flywheel in place. Then when the engine was above idling throttle, the flywheel slipped, giving a false reading from the Crank shaft sensor.

So they stripped it all down, changed the key, tightened the chain etc checked the water pump etc and hey presto!

Its running like a babe. Its so responsive and sounds beautiful. They said the nut was that tight  could have been holding like it for a while. Anyhow i'm so happy now and so are my credit card company. Thanks everyone that gave an input.

See you all at Mallory on Sunday.