So my 4.2 supercharged was running fine up until about 6 weeks ago.

I did an oil service and noticed a split vacuum line to the LPG.

After replacing said line and doing the service it suddenly started doing long cranks every morning when I go to start her.

I really can’t see how what I did is connected?

Anyway since having the problem I had initially blamed the LPG so I have disconnected everything I can and disable anything else to do with LPG to rule that out. The fuel pump is only 4years/36k old so left that but did a filter.

It has decent rail pressure and waiting as the key is turned a few times doesn’t make any difference.

I should say that once started it drives exactly as normal as it should.

What am I missing here? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Try resetting engine adaptations

02 sensors may have drifted way out of whack with the vacuum leak.

Just guessing here, but worth a try 👍

Forgot to say tried that multiple times to no avail - the problem was worse after running lpg which led me to disconnecting it but still having issues Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Hey Dan

Did you ever get to the bottom of this issue?

Mines playing similar games, excess cranking on first start of the morning, after that everything is fine, don't know whether it's petrol flashing off in the fuel rail or not but suspect that's the problem, its quite hot sitting in the morning sun lately.

Fuel rail sits at 65psi but unable to check what it is before fuel pump starts.

Tia

Yea - I did fix it and it was the same as it was last year… a bad lpg injector… it sticks open when the car is off and fills the manifold with gas so needs the cranking to clear the gas.

Last year it was easy, it misfired on that cylinder so I just changed that injector. This year not so lucky it ran nice on gas. I ended up buying the remaining 7 and it was fine. Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Cheers Dan, maybe the same for me, I've isolated the gas side of things to eliminate that possibility, I'll see how it goes next few days, it's only on hot days so the under bonnet high morning temperature isn't helping when it's sitting in the sun , soon find out whether it's lpg side or petrol side....

🤔

34 degrees and started first crank, just need to determine which lpg injector/s passing now

👍

If you want to stop those lpg injectors from sticking give them a good shot of wd40 once in a while.