Stall on cold start (not driven 2+ days) --> Stall on cold start every morning

Hi all,

I have a weird problem with my 2004 320i which I'm hoping someone can help me out with.

A few weeks ago I noticed that if I didn't drive my car for 2 days or more, on a cold start it would fire and then immediately stall on the first attempt. On the second attempt, it would start fine, idle rough for a second or so and then idle normally.

I took it to a local BMW specialist and he found that the breather hose had cracked, so he replaced it for me.

Since having that replaced, the car now stalls EVERY morning without fail.
However when starting on the second attempt, the rough idle seems to have disappeared.

These issues don't occur when the car has warmed up.

I've searched around these forums for similar experiences but I've not spotted any but if they're out there, feel free to point me in the right direction.....

Thanks in advance.

*** EDIT ***

In an attempt to track down where this problem may lie, here's what I've done so far (and still plan to do) - all done first thing in the morning with the car cold:
- Tried a different key (no change)
- Tried starting with MAF disconnected (no change)
- Tried 'priming' the engine before starting, i.e., turn key to ON position, let fuel pump run, switch off, then back to ON, let fuel pump run, then try START (no change)
- Tried starting while slightly pressing on the accelerator pedal (started first go, no stall!)
- So now, for the next test I plan to briefly engage the starter motor (just enough to turn the engine over but not enough that it fires up). Then after that, attempt a proper start.

The aim of this is to work out whether I might have leaking injectors once the car is cold....

It looks like the only thing that works for me (well, more of a workaround for now) is if I press the accelerator pedal slightly whilst starting - it fires up no problem.
But if I try to start it the following morning without touching the accelerator, it stalls on the first go, but starts fine on the second.

Any ideas what this could be? It's VERY frustrating......

I had the same thing and after about 6 months my fuel pump finally died on the road. I was able to start the car again, changed the pump the next day and that also cured my cold start problems.
So, advice is to check the fuel pump pressure (before that you can try and change fuel filter, which should be done anyway if you change the pump) to see if the pump is dying.

If your problem goes away after the car is warm and runs completely fine. It's probably your Vanos seals. How many miles on the car?

Thanks for the responses - appreciate it

Voona, I'll get my BMW specialist to check the fuel pressure. Not sure if the fuel filter has ever been changed. Also, I've tried 'pressurising' the fuel system in the mornings (turn to ON position, let pump run, turn off, then back ON again, let pump run then START) and this didn't make any difference. Perhaps that test wasn't a good way to check if it's a fuel pressure problem...

MalibuMafiaV, the issue only happens when I start the car first thing in the morning. If I start it without touching the accelerator, it'll stall straight away. If I try again straight afterwards (again, not touching the accelerator), it starts without any problem - and the car is still stone cold at that point so not sure if the VANOS seals would do that - or would they?
I've got just over 91,000kms on it (so just over 56,500 miles).

The puzzling thing is that this started happening after the breather hose was replaced. Perhaps it's just a coincidence and has nothing to do with the breather hose....

Originally Posted by techit

Thanks for the responses - appreciate it

Voona, I'll get my BMW specialist to check the fuel pressure. Not sure if the fuel filter has ever been changed. Also, I've tried 'pressurising' the fuel system in the mornings (turn to ON position, let pump run, turn off, then back ON again, let pump run then START) and this didn't make any difference. Perhaps that test wasn't a good way to check if it's a fuel pressure problem...

MalibuMafiaV, the issue only happens when I start the car first thing in the morning. If I start it without touching the accelerator, it'll stall straight away. If I try again straight afterwards (again, not touching the accelerator), it starts without any problem - and the car is still stone cold at that point so not sure if the VANOS seals would do that - or would they?
I've got just over 91,000kms on it (so just over 56,500 miles).

The puzzling thing is that this started happening after the breather hose was replaced. Perhaps it's just a coincidence and has nothing to do with the breather hose....

Humm pretty low mileage if that's the case it probably isn't your Vanos seals. Is the check engine light on?. What codes do you get if so?.

Originally Posted by MalibuMafiaV

Humm pretty low mileage if that's the case it probably isn't your Vanos seals. Is the check engine light on?. What codes do you get if so?.

I've got no warning/check lights showing on the dashboard.
When I asked my mechanic about error codes, he said there wasn't any (I don't have my own scanner unfortunately......)

Just thought I'd post an update on this ongoing saga.....

I decided to switch fuel companies on my last fill up. Since doing that, my car doesn't stall every morning anymore.
Just when I thought it was fuel related and that was the end of my problems.......well, not so :-(

On Saturday, I parked it in the garage and left it there for the rest of the weekend.
This morning (Monday) I go to start it.....stalled straight away.
Tried a second time - started without a problem.

So, I'm now back to stalling every second day again......pffft....go figure.....

There is one more thing I want to try - but will have to wait until I can leave it for another weekend or so.

Will post the outcome.

try cleaning your MAF with CRC mass air flow cleaner

Originally Posted by three28iguy

try cleaning your MAF with CRC mass air flow cleaner

Have tried starting without the MAF connected when the problems first appeared.
Made no difference so I don't think it'll be that.

OK - have managed to narrow this down to the fuel system, somewhere.

It seems that if I 'prime' it by running the fuel pump 5-6 times before starting the car, it starts first go without any problems - even if it does sit there for 2 days. When I first tried this, I was only running the pump 2-3 times and it didn't work. Going by that, I'm thinking there's not enough fuel pressure for a cold start.

So now it's a case of working out which part(s) may be responsible......

Dunno if this M54 saga will help:
- How to diagnose a BMW M54 cold-engine intermittent misfire (1)

Thanks to everyone who has responded - appreciate it.

It looks like my problem may have FINALLY been solved.
As suspected in my previous post, it was a fuel pressure issue. Basically, if the car wasn't driven for more than a day, the fuel pressure was dropping to a point where there was barely any pressure left (I think it was only 1 bar, if that). So when I did eventually go to start it, the fuel pump wasn't generating enough pressure to get it back to where it needed to be for a proper start - hence why I had to 'prime' the system 5-6 times. The fuel pump itself is OK.

The problem part was the fuel regulator that's built-in to the fuel filter - I understand this is also responsible for maintaining fuel pressure.
The fuel filter was replaced, and after letting it sit for 2 days, now when I start my car it starts first go.

A bit of a painful experience, but got it sorted out in the end.
I hope this thread helps someone else one day :-)