M42 Cold Start intermittent problem

[mrjonchandler]

Hi All,
318 is / m42 engine / 130K, full service history.
Occasionally, with a cold start the engine fires, revs up to 2,500 rpm and then stalls.
A second attempt usually works, but could anyone shed any light on the problem?
Also, econometer doesnt seem fluid, either sticks a bit or doesn't work, temp gauge not working either. i've had the cluster out and the brass nuts were tight. All went back in ok. More worried about the stalling really, any help appreciated.
Thanks
Jon

[asmith88]

have you checked the resistance of the blue temperature sensor?

[mrjonchandler]

No i haven't as yet, although i replaced the blue sensor not so long back.
What should i check for in terms of the multimeter?
Cheers
Jon

[alync205]

I'd say it would be a good idea to check the idle control valve.It could possibly be sticking.You could take it off and clean it with carburettor cleaner to see if it makes a difference.

[mrjonchandler]

Thanks,
I'd really like to get the sensor changed below the inlet manifold but cannot seem to find a way to acccess it without taking the manifold off. This is may be affecting everything else too?
Cheers
Jon

[Touring Whore]

The sender right under the manifold is for the guage, and wouldn't affect running.

The sender to the left of it (from passenger side) is the one which would affect fuelling, and it *looks* like you could get at it without the manifold coming off.

I don't know if a dodgy blue temp sensor would cause your problems with cold starting, but regarding your temp guage - have you checked your SI board?

[mrjonchandler]

Well, regarding the temp sender, i have had the cluster out, everything else works, the econometer is intermittently working and the temp gauge is not working but twitches when you turn the ignition on. I have ordered a new sender from BMW today, don't really know much about the SI board, what do you know?
Thanks TH!
Jon

[Touring Whore]

Within your cluster is the SI board, you need to remove the cluster, remove the rear of the cluster and you'll see a circuit board (held in by a small bracket in the middle). Remove the board and look for signs of the batteries leaking. The SI board can cause many strange faults with the instrument cluster, including a temp guage not working.

Easiest thing to do is swap the cluster for a known good one, see if it cures the problem.

I've just had a cluster with everything working bar the temp - turned out it was the SI board. SI board failing is a common fault, plenty on here about it.

HTH

[mrjonchandler]

Right, we're onto something then.
I totally forgot that the Service Indicator is stuck on. If i changed the cluster would that not affect the mileage counter, i want to keep it original if possible.
What are the batteries needed? Would the SI indicator being cause the gauge not to work or vice versa?
Thanks so much for your help, the more money i can save on this, the quicker i can get the rocker cover!
CHeers
Jon

[Touring Whore]

Changing the cluster will change the mileage, but if you do it as a temp measure you can see if your guage springs back to life or not. If it does, just swap the SI board from the working to the non working. If not, you can worry about the sender/wiring.

If the batteries have leaked new batteries won't help, the board will be damaged and it will be easier to get a new SI board thank repair the old one (in most cases)

The SI board controls the guages, when it's damaged/failing the guages do wierd things. The guage, sender and wiring might be fine, but if the board isn't working as it should you won't ge the right reading.

Best thing to do is have a search for "faulty SI board", I recall reading a post where BrianMoooore states what intruments are affected by the SI board (all but the Speedo I think). You'll find out more than I can tell you.

As for practical fault finding - take your SI board out and have a look, or get hold of a good SI board/cluster and see if it cures your problem.

[tez180]

Just swap the cluster to check, then put your speedo onto it. Keeps the milage. Job done.

[mrjonchandler]

Does anyone have an SI board guide? Or what the SI board can affect?
Ta
Jon