A4, AWX, 2002 - How do I check N75 solenoid correctly

[drv]

Hi
Seems i have been doing it wrong for the last 25 years then, will need to build up more knowledge. Still interested in what switching ignition off and then back on actually tests though, guess i will never know now.

[Crasher]

I would still check the actual boost figure to see if the MAP is sticking or over reading. The ignition off reset is a classic symptom.

[guerrra]

hi,
clean the turbo the vnt is stuck with carbon probably....
guerrra

[Gary s]

hi,
clean the turbo the vnt is stuck with carbon probably....
guerrra

I suspected this first and gave the customer e few bottles of Forte diesel treatment to try.
He thought it had cured it but came back a few weeks later, so I booked it in for this Friday to investigate.
Seems to be a lot of arguing regarding the procedure for checking this fault.
would be nice if someone could clarify the test procedure step by step.

Gary

 

[guerrra]

remove the turbo and get it clean, the Forte diesel treatment, does not clean it as wel as stripit.......no.
had a few of those and wen no vac leack , try new or known good n75, if noting solve i send the turbo for cleaning and all ok then.
guerra

[Crasher]

Basic adjustments 11 or 15 I think and watch the actuator move up and down. If it fails to move but you can see it trying, give it a gentle prod.

[drv]

Hi
Please refer to the Frank Massey article I mentioned in previous post if you what the correct procedure this will tell you exactly where the fault is. Most times it does turn out to be the variable vanes sticking, but this could be because of carbon or if it has stood for a period of time at some point, the casing that the vane control ring runs in will be restricted from moving correctly, especially when the turbo gets hot. You can remove the spring clip that locates the actuator on the pivot and feel how the vanes are moving, but unless you have a lot of experience with this i doubt that you will tell if it is correct or not, but worth a try. The turbo can be removed, partly stripped and then you can manually clean the casing, vanes and control ring but do a thorough job and do not remove the 3 torx screws from the center casing as they will break, reassemble and if done correctly you will feel the difference. Just a warning, some of the bolts may require heating before they will loosen, but do all testing first as you may save yourself a few hours.

[Gary s]

Check the actual charge pressure in measuring blocks 08, display group 011, block 3 to see if it is sticking at 2880mbar.

Hi Crasher your 100% right.
Block 11 worked actuator in basic setting everything worked fine and seemed smooth.
Noticed actual boost was in deed stuck at 2983mbar
Checked sensor supply and was OK, check the two outer terminal voltage and was 4.7v when it should have been around 1.7volts
Replaced sensor and everything perfect, car now drives like its been chipped.
Thanks again Crasher for helping diagnose efficiently.

Regards

Gary 

PS tried to attach before and after logs but when trying to post got a message saying I can't attach that type of file, it was just an excel file from the vag logs  Maybe Derek can help me on this or I can email anyone who wants to see them.