E46 318ti Compact - Engine Stuttering Intermittently

[jammy_basturd]

Girlfriend just bought this car from her brother. He's had this happen to him in the past before, but not very frequently. He's had the fault codes read, but said nothing came up, which we believe, he's a trustworthy fellow.

The car drives and idles fine, however once or twice every hundred miles or so, it seems the engine just shuts down for a split second. The loss of drive causes the car to jolt a bit, and the revs to dip, however the engine usually picks right up again and carries on driving fine. It can happen two or three times in a row, and it was worst the other night when it happened several times in succession and the engine completely died. If it is a bad one then the battery light will sometimes come on, but then will go out once the engine has picked up again.

This doesn't affect anything else; lights, radio, etc all stay on.

[Gallen]

sounds like a loose connection somewhere?

Possibly coil? Immob? Ignition (even the key barrel)? Fuel pump?

[jammy_basturd]

Yea, sounds like what I was fearing. I kinda wish it was something like the cam sensor or crank sensor, least then it would show up as an ECU fault and the problem is easy to pinpoint. Was kinda hoping I wouldn't have to crawl around the engine bay looking for a dodgy connection! :S

[fixedwheelnut]

Best thing to try is the DME power relay, I have had a few at work that mess around they get a high resistance across the contacts and once it has been driven a while the power supply voltage drops and the engine cuts out or misses.

It doesn't register a fault because it just thinks you have switched the ignition off, cheap and easy to try less than £10

If it still faulters after that get the memory read again and check power supplies and earths to the control unit.

[jammy_basturd]

Excellent, cheers fixedwheelnut, just the advice I was looking for! I had thought it might be a relay, but was waiting on a manual of sorts to find out which ones it might be. Will get the DME relay ordered today!

[*Raz*]

Thanks for your help guys, I really hope it fixes it, its driving me crazy!!! THis is meant to be my reliable car .

Im going to get a Haynes manual for it at the weekend too!

Its still a gorgeous car