Help needed

[gingerrusta]

Driving my 325i auto cabriolet this morning and it started spluttering and missing and then just cutting out.
It wouldn't start without a jump start but the car has a brand new battery on it .
Once started it doesn't hold normal revs and just cuts out again.

Any ideas guys ?

[BenHar]

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

Ben

[Stefan on probation]

Did you do any other work to the car as I once had an issue with a car running rough which was down to not tightening the jubilee clip to the hose for the air filter box and it had become loose.

[Speedtouch]

With respect, I doubt an airbag hose would have much to do with it!

Start with the obvious - has it got enough fresh fuel, and is the engine-to-body earth strap in good conductive condition?

Other likely suspects are the crank position sensor, and possibly leaking fuel hoses or blocked fuel filter, and a failing DME/fuel pump relay.

[Brianmoooore]

It wouldn't start without a jump start but the car has a brand new battery on it .

This is very strange! The starting performance with jump leads from an external battery should always be lees than a good on board battery, because of the resistance of the jump leads - especially with average DIY leads, which aren't usually of very good design.
Unless this is a one off coincidence, I would be looking at the fuel pump.
Pull out the fuel pump relay, leave your jump start battery negative lead connected, and connect the battery + to the 87 (marked on the relay) pin of the relay's socket. This should make the fuel pump run continuously from the external battery, which you should easily be able to hear.
With the pump already running, try to start the car.

[Stefan on probation]

With respect, I doubt an airbag hose would have much to do with it!

Start with the obvious - has it got enough fresh fuel, and is the engine-to-body earth strap in good conductive condition?

Other likely suspects are the crank position sensor, and possibly leaking fuel hoses or blocked fuel filter, and a failing DME/fuel pump relay.

Grrr sausage fingers air filter box..........

[gingerrusta]

More investigation found the alternator wasn't charging . The car is running ok now but just started it after it's cooled down and is a bit lumpy first off but then idle improves .

[Speedtouch]

That would explain it. The battery may have fallen below the threshold voltage required to power the ECU, so it will now have to relearn its base idle settings, etc.

[Brianmoooore]

Battery warning light not lit?

[gingerrusta]

It was strange but I don't remember battery light coming on but the abs light came on ? Since replacing the alternator the abs light has gone out .
When I was at my friends garage he plugged it into a machine and it did have an error code

AIRFLOW SENSOR CIRCUIT

[Brianmoooore]

ABS light will have reverted to the legally required 'test' mode that it enters when you first switch on the car. It leaves the test mode when sufficient voltage is detected from the alternator's D+ terminal - the same voltage that extinguishes the battery light.
Does the battery light work now?
Wouldn't take too much notice of fault codes thrown up by early Motronic, especially when the electronics has been subjected to a falling battery voltage. Delete the code (disconnect battery?) and check again after a couple of weeks of normal running.

[gingerrusta]

Yes I went to the ace cafe last night and all seemed fine. No random lights etc . The error code that came on the machine was deleted off at the time so like you say will check it again in a week or so.
My idle is a little low and ticks over fine when the car is warm but on a cold start is lumpy