car cutting out

we have a bmw e46 engine n420b at 40mph when you depress the clutch the car cuts out or when you freewheel any ideas

Hi,
Well its worth checking for vacuum leaks... carefully examine the the hoses for splits and holes or loose hose clamps...

I have heard of crankshaft position sensors causing this complaint..

It could also be a fuel delivery issue. Low fuel delivery pressure, caused by a faulty pump perhaps...

Does it start up immediately after cutting out?

the car does start straigh away and we have changed two cam sensors and the crank sensor all bmw parts

pinetreemotorcars wrote:the car does start straigh away and we have changed two cam sensors and the crank sensor all bmw parts

Ok... Do you have an OBD II diagnostic reader? or have you had the fault codes read? Cheap enough to obtain and most garages have them these days...

If you then post up the code we can pinpoint your problem, even if it doesnt throw up a fault, we can still narrow this down somewhat...

the car has been to bmw for diagnostic and come back all ok we just want to see if anyone has any ideas cheers mate

pinetreemotorcars wrote:the car has been to bmw for diagnostic and come back all ok we just want to see if anyone has any ideas cheers mate

Ok, MAF (mass air flow) and oxygen sensors will not necessarily show up on the diagnostic if they are faulty... because they are variable resistor sensors they can just lose efficiency but the ecu think they are correctly working.... oxygen sensors generally cause over fuelling and MAF's will not measure the air flow correctly causing a cut out problems.... other than that, if you have changed the crank and cam sensors and providing the engine is'nt terminally ill, it is likely to be fuelling, weak fuel pump or dodgy relay...

thank you very much we changed the m a f meter and changed the thottle possition and it has seemed to have cured it so thank you again regards

dave francis