changed coolant and boost level dropped !

[220bhp]

I changed my coolant today, and I got an air lock,it caused the car to run over the normal 90%. I topped the car up and ran it up to temperature with the cap off,and the heater turned to max. I got all the air out that I could, and there where no more bubbles ,car then ran at the correct temperature, if any thing a little lower 85%.
Now the car will only boost to o.6bar, and then drops to 0.4 mechanical boost. I have reset the ECU by disconnecting the battery, but it still do's it.
Could this be coincidence ie boost leak, or could it be due to this temperature spike. I did notice that some water had been pushed out of the header tank due to the air lock
could this be the cause in some way.
Any ideas would be much appreciate the thought of running on low boost is not good, Ive gotten use to it now you see

[Acidburn]

Check u got all the air out of the system by undoing the screw on the top of the radiator slightly so it works like a pressure cooker and whilst running the engine top the fluid up till you get decent warm air out the heater and the fan kicks in.

I'd try that first then try leaving the battery off for a bit and trying ti again.

[220bhp]

Just double checked all this Pete, I am quite sure there is no air left in the system.
The temperature is now running right ,no water loss,all ok except the boost, disconnected battery for half an hour, still the same.
What else other than a boost leak, (and I have tested for that) would cause this,

[4WheelDrifter]

It sounds like a MFTS problem. Have you knocked any wires/connectors while you have been working?

[220bhp]

MFTS was replaced when Ihad the engine out last year, but I will check the wires ,chears Stu

[220bhp]

Checked the wires on MFTS and all seem ok.I did notice that one of the two wires on the small plug in front of the MFTS was of so I replaced it and reset the ECU but still the same.

[4WheelDrifter]

Silly question, but have you checked for fault codes?

[220bhp]

Code 4444

[4WheelDrifter]

Code 4444

Hmmm.. That's not very helpful is it?

Have you disturbed any knock sensor wiring? That can cause the boost to drop back to mechanical level without a code IME, it normally returns after you reset the ignition, then drops back again when the fault occurs.
I'm just trying to think why a coolant change would cause this kind of fault.

[LHD_Kid]

Might be worth checking the ECU temp sender thingy, on the back of the engine, if you unplug it and put a meter on it you should get a reading..... due to my memory being like a seive I can't remember what it should be, but it is on here somewhere...
HTH
Chris

[4WheelDrifter]

Link to info on G62.

[alg]

Not logical given the coolant change should not have disturbed it but do check the WGFV is operational & wiring intact. Caused my only drop to mechanical boost.

[220bhp]

I have just tried to check g62 with a multimeter, not easy, plus I am not sure I have done it right, not good on the electrical front me. anyway it reads 45.5 omhs not 2500
I have no idea what that means if the reading is correct I will try it again to make sure
Would g62 give a fault code. What could cause the boost to be cut that would not so a code, for that mater what would cause it any way, Baffeled and pissed of right now, and in need of help before I loose all reason and by a BMW

[Keeper of The Kitten]

Arrrrgh!!! NOTHING is THAT BAD!!!

[220bhp]

ANYONE