Hi all,

I've got a very hard cold start on my 740. When the car is slightly warm or at operating temp, it starts up in 2 secs. When i try to start it first thing in the morning, it cranks very hard and once it actually comes to life the RPM stutter quite a lot for a couple of seconds like the car is about to stall, until the car goes to normal idle RPM. If you shut it down right after that and try start it up again, it will start up first try in 1 second.

I've replaced the coolant temperature sensor, cleaned the throttle body, there are no vacuum leaks, also done the fuel pump check valve and the fuel filter. The external fuel pump is fully functional and so is the FPR. I am suspecting there is no fuel pressure at startup, but how can this be since i've replaced the check valve? Just to note, the MAF is not the problem.

I'm not sure if this has something to do with the harness, as i'm aware of the problems with the biodegradable harnesses but i don't actually know of a way to test this?

Any help would be appreciated.

 

Also I've had the distributor, all spark plugs and leads replaced 2 years ago. Shouldn't be a problem.

 

Hi mate,
Just wondering if you were ever able to solve this problem at all? I have EXACTLY the same issue with my Volvo 760- really curious as I desperately want to solve it!
Cheers!

 

It ended up being the ECU. Swapped it over and it fixed everything.