2.0 tdi turbo boost problem intermittent

[dogofmadness]

Hi everyone

I have an A6 2.0 tdi 2005 with BLB engine.
When accelerating through the gears, initially there is no boost, then at some point the turbo kicks in giving full power. There is no pattern, it could be after a couple of seconds in 2nd gear or a few minutes later in 5th.

I have a few error codes from a Snap On scanner;

01262 solenoid valve for boost pressure control N75 could be short to ground, short to plus, or output open or faulty valve

16786 EGR excessive flow.

Before I fit a new N75 can anyone tell me how to check the wiring to the valve with a multimeter or what reading I should get at the connector. I don't want to fry the new valve if the loom is faulty

Don't really understand why the problem is intermittent . Any help or advice gratefully received.

Thanks

[joshA6]

Not sure what the resistance should be at the terminals as IU have looked in the past but no values are given in the workshop guide.

Before chaning the N75, have you checked the vaccuum pipes. If they are split or worn, you won;t get the pressure required to open the valve.

Also, take the pipe off the EGR valve to see if the flap is still working. It may have sheared off it's housing so it is not opening. It should be open when engine is idling and will shut when you give it revs. Again, this also has a vaccumm pipe.

Hope this helps, try the cheap things first

[dogofmadness]

Thanks for that.
Visual inspection of vac pipes look ok but I will check each one with a vac pump. Egr valve has been cleaned but I didn't check it with engine running. That will be next job
Cheers

[joshA6]

Also, check the fuses for the respective components.

I had a friend with a mk5 golf with EGR faults (and other faults as well). He got the EGR replaced and it kept coming back with emmissions workshop. He brought it over to me, and when I scanned it and did some digging, I realised that a blown fuse was causing all the faults. I doubt his EGR had ever been faulty and so the garage wasted £300 of his.