17964/P1556 - Charge Pressure Control: Negative Deviation

[martin1810]

You need to attach logs as .zip file. The .doc file is difficult to read. It looks like your turbo is working fine. Do another log from 1000 - 4000 showing rpm, N75 duty cycle , boost pressure, MAF.
You may have to do a couple of logs to get all the data. Just make sure rpm is with each log.

[Jamiem]

change the extension back to csv and it will open in excel fine What group is n75 cycle in?

EDIT, just looked at your site, looks like groups 1, 10 and 11 you want logged? Ill go do it now

[martin1810]

Yep. Opens ok as .csv. I can't work out which boost is logged. Specified or actual. If you log 11, you will get rpm, boost spec, boost actual and N75%

[Jamiem]

Here ya go

[martin1810]

Is it still giving underboost fault code and has it been remapped.

[Jamiem]

Yes and yes. After the first logged run it then went into limp mode and logged the 17964 code again.

[martin1810]

The signals to the N75 valve are ok but that doesn't mean the N75 is doing what it should. It is working though. The most likely suspect is still a vacuum leak. A mityvac is the best way to test the vac pipes. A diy alternative is to VERY gently pump air into the vac pipes with a bicycle pump and see if the system holds pressure. The pressure must be little more than blowing up a balloon or you may damage something.

[Jamiem]

Should it be sealed from one side to the other when the engine is off? I can blow in to one side of it (say the turbo actuator side) and air will come out the other side, but not at full pressure, leading me to believe its leaking.

[martin1810]

Pull the pipe off the turbo actuator and blow into the pipe. You shouldn't be able to.
Also try sucking on the turbo actuator to make sure its diaphragm is ok.

[Jamiem]

I can blow through the actuator pipe in to the N75, and if i put the hose on the actuator, i can draw a vacuum and the actuator moves easily. I'm sure my N75 has gone belly up