M3 - Intermittent – Start then Dies……

[yanto]

Very strange, it has only happened twice over the last month or so. M3 is running perfectly. However, about a month ago I was driving for about half an hour, stopped to pick something up (maybe 10mins) Went to start - It fired up then dies. This happened five times. I let the car sit for a few minutes and it fired right up – No more issues….Then just a few days ago, it happened again. Same problem, the same sequence of events. Fires ups, dies – 3-4 times. Let the car sit a couple of minutes, fires up, and runs. Nothing since. I was thinking maybe the fuel pump or fuel filter but I don’t have any problems when the car is running. Any ideas?

Cheers all.

[Arith2]

Very strange, it has only happened twice over the last month or so. M3 is running perfectly. However, about a month ago I was driving for about half an hour, stopped to pick something up (maybe 10mins) Went to start - It fired up then dies. This happened five times. I let the car sit for a few minutes and it fired right up – No more issues….Then just a few days ago, it happened again. Same problem, the same sequence of events. Fires ups, dies – 3-4 times. Let the car sit a couple of minutes, fires up, and runs. Nothing since. I was thinking maybe the fuel pump or fuel filter but I don’t have any problems when the car is running. Any ideas?

Cheers all.

I would get codes pulled. EWS could be taking a dump. I had the same symptoms when mine crapped out. A quick diagnosis would be to disable(if there are absolutely not fault codes) and try again. Don't let anything go to sleep as it may reset and work. Just use Martyn's Tool. If it isn't well the tool will still be extremely useful to have. I'm not saying this is your problem as many different things could be wrong but this is one of the cheapest things to try. Fuel pumps go bad as often as the EWS. Better not to throw parts at it. I've seen a bad DME do this but it's very unlikely yours is bad. Still, check for all the screws on the lid. Buy a pressure guage and check fuel pressure when priming.

[jet_dogg]

Very strange, it has only happened twice over the last month or so. M3 is running perfectly. However, about a month ago I was driving for about half an hour, stopped to pick something up (maybe 10mins) Went to start - It fired up then dies. This happened five times. I let the car sit for a few minutes and it fired right up – No more issues….Then just a few days ago, it happened again. Same problem, the same sequence of events. Fires ups, dies – 3-4 times. Let the car sit a couple of minutes, fires up, and runs. Nothing since. I was thinking maybe the fuel pump or fuel filter but I don’t have any problems when the car is running. Any ideas?

Cheers all.

It could be the crank sensor.

[yanto]

Thanks - No codes are present. The car did fire up but then died, if it was the EWS the car wouldn't even fire up, correct? Any additional information on "Martyn's tool" ?

[MarcZCP]

I've had the same problem in the past, and currently EWS is my prime candidate.

To answer your question yanto, the EWS could indeed cause this exact symptom. If the EWS is unhappy it will either prevent cranking altogether, or it will cut fuel JUST after startup, so you do get that initial fire up but it dies immediately.

In my case, I did have codes. In the DME, there was "EWS 3.3 Anti-tampering protection", and in the EWS there was "Toleration of changing code increased, key 1", and the same code for key 0 as well. Note that these codes require a decent scanner, they don't show up on a generic OBD2 tool, and there is no check engine light associated with these. I use BMW scanner (PAsoft).

My suspicion is that battery voltage might play a role here. I have a dashcam that is always on, so fairly high parasitic drain when the car is off. At some point a couple of years ago I got into the habit of leaving the car on a battery tender when not driving and I've never had an issue since.

"Martyn's tool" is ECUworx. It is a user-friendly way of changing several items in the DME, including EWS disable. It needs a cable to work, and also separate software (like BMWflash) to read/write to the DME. Note that I haven't done any of this coding myself yet, so hopefully someone more knowledgeable on ECU coding can confirm/correct this.

Good luck, and keep us posted. Interested to hear whatever your eventual findings are.

[ac427]

Thanks - No codes are present. The car did fire up but then died, if it was the EWS the car wouldn't even fire up, correct? Any additional information on "Martyn's tool" ?

If you have a spare key, try it the next time the fault occurs.

[c watson]

Crank sensor or fuel pump could be on its way out. As mentioned above I would scan for codes first unless you want to take a chance throwing parts at it.

I came across this thread. There’s some useful information in here.

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/22903-two-years-of-intermittent-hard-starts-please-help

[simon_c]

Do you have a manual? I had intermittent starts a long time ago and it ended up being clutch pedal switch that needed to be replaced. It was a cheap place to start if anything.

https://www.fcpeuro.com/products/bmw-clutch-switch-61319231129