How do i test the N75 on a 2.5 TDI?

[Rudidudi]

As above, im in the process of needing to test the N75, as well as other things such as the VNT, turbo etc.

I thought I'd kick of by checking the N75...

Any pointers appreciated as Im new to this engine.

cheers

[Doctle Odd]

N75 wastegate actuator valve explained/symptoms. - AudiWorld Forums (http://forums.audiworld.com/showthread.php?t=2780449)

you can also take off the pipe from the N75 to the actuator and check if the turbo is boosting, not really recommended tho!

[Rudidudi]

N75 wastegate actuator valve explained/symptoms. - AudiWorld Forums (http://forums.audiworld.com/showthread.php?t=2780449)

you can also take off the pipe from the N75 to the actuator and check if the turbo is boosting, not really recommended tho!

Cheers for the link http://www.vwaudiforum.co.uk/forum/images/smilies/smile.png

Thing is that it is really slow from idle, i mean REALLY slow, and only picks up acceleration after say 2-3k revs.

I cant say ive even heard the turbo whistling, so this is something i want to check first....

how can i check if the turbo is boosting? Presumably a boost gauge and t piece and see it there is boost? Any other way?

[Doctle Odd]

If the turbo was boosting on that car you'd know. check the vacuum lines intake pipework and vanes foirst

[kid-jensen]

I would imagine the boost is one of the parameters available on the ODB2 connector under the dash.

About a tenner on a ODB2-to-Bluetooth adapter, then a fiver on the "Torque" android App, and all wil be revealed (along with some diagnostics and loads of other fascinating stuff). Even record your 0-60 time, should you be slightly masochistic..

Put the phone somehere in your eyeline when you're driving though, it's all too easey to get distracted when reading a screen tucked into the ashtray...

[Doctle Odd]

Or, alternatively ask a member of this site with VCDS to get you live data, OBD software doesn't work well with VAG vehicles have a read here Ross-Tech: VCDS: DTC Comparison (http://www.ross-tech.com/vag-com/dtc-comparison.html)

[ametlib]

Or let the engine idle and pull the rubber hose of the VNT actuator, then put it back again. Actuator arm should go all the way out, and back agains the stop screw again ( and do so, smooth)

[PaulF2.5TDi]

To test the actuator, look at the position when the engine is off. The actuator should be full down (as looking at the engine in situ) when the engine is started, the actuator should rise to the stop screw.

To test the N75, you need VCDS, go to basic settings, block 11. The N75 will cycle every 10 (ish) seconds and you can watch the actuator move up and down. Make sure it moves all the way up to the stop, and all the way down.
If it doesn't, check the vacuum from the N75 first, then the vacuum to the N75 by removing the pipe with the engine running and sticking your finger over it (unless you're a big whining girl)

If you are having boost issues, google Mr Muscle turbo clean and check your pipes before changing the N75.

[MrAff]

If it does turn out to be your N75, I have a working spare lying around you can have for cheaps. ;)

[Rudidudi]

If it does turn out to be your N75, I have a working spare lying around you can have for cheaps. ;)

cheers, will test and let you know....

[Rudidudi]

If it doesn't, check the vacuum from the N75 first, then the vacuum to the N75 by removing the pipe with the engine running and sticking your finger over it (unless you're a big whining girl)

I read the mr muscle posts with interest and hoped that you'd post :)

On the N75, is it the pipe that comes from the actuator above the VNT that i need to remove?

Ive asked elsewhere but is the vacuum hose 3 or 4mm i/d? also do any other critical hoses perish or are the vacuum hoses the problem ones?

[PaulF2.5TDi]

The N75 has three pipes.
One from the vacuum pump, one to the actuator and one to air (via the air-box, IIRC)
If you pull the line off the actuator with the engine running, there should be vacuum at the end. I can't remember the ID, but it's common enough stuff.

I thought I saw your post on ASN - Scott had similar issues with his 1.9 so a good read there should help too.

[Rudidudi]

ive added some vids and pics here:
A6 2.5 TDI slow to pull away from idle - Page 2 (http://www.vwaudiforum.co.uk/forum/showthread.php?143476-A6-2-5-TDI-slow-to-pull-away-from-idle/page2)

comments and help appreciated.... :)