BMW E46 Fanatics Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
Our daughter's car has decided to demand attention. On a Sunday, of course. Just after we'd decided to sell it. (When else??) The plan was to find a good E46 318Ci with the M43TU engine and an automatic gearbox... That'll have to wait until this is sorted.

While driving at a constant speed and throttle position, the engine will hesitate. It is as though it is running out of fuel - there's no warning lights (and 3/4 tank of fuel). The hesitation will last from a fraction of a second up to 2-3 seconds, during which no throttle activity makes any difference. Then the engine will pick up again and run as if nothing is wrong. No touching the ignition key, no gear changing - no action taken and it'll suddenly be fine. And then it'll cut again.

Perhaps more accurately, it is as if the fuel supply or the ignition just cuts out for a brief period of time.

It might do this several times in a minute, or it might not happen at all for several minutes. It happens under acceleration as well as under constant throttle.

When ticking over, the 'hesitation' can be enough to stall the car. Tickover - idle - is typically very (very) slightly rough but I had put this down to it being a few rpm below ideal idle speed rather than any significant issue.

When stationery the engine will typically rev freely and without problem. We have sat in the car with the engine idling for 10 minutes without an issue.

I've not been able to read any codes - I was recently made redundant, and the laptop went at the same time the job did. I do have an older Compaq which I'm waiting for a PSU for, but (of course) that's not arrived yet. I'll obviously check codes ASAP.

Any ideas? Checking the spark plugs has been suggested but I can't see how that it is going to cause a complete cut in the way we are experiencing. Given circumstances cheap fixes rather than random replacement of expensive parts is much preferred! I was thinking of starting with a fuel filter given I've not replaced that.

TIA.
 

·
Registered
Joined
·
71 Posts
How about a clogged or old fuel filter? I would check/replace that first, especially depending upon mileage.
Next through is the fuel pump, perhaps it is aged and cannot keep proper pressure in the fuel line.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #3
Apologies - I should have updated.

Problem turned out to be the cam position sensor. Nicely located on the front of the engine, but requiring removal of a lot more kit than seems necessary in order to get to the wiring! Not difficult to replace, but has certainly resolved the issue.

Thanks for the suggestions, though. These are certainly things which any owner should be looking at.
 
1 - 3 of 3 Posts
Top