finally figuered out how to post a VCDS log.

[onetwo]

i can pretty much redline 1st, 2nd and it will go into limp mode in 3rd gear under heavy throttle. all the vacuum lines have been replaces as well ass the maf. ,air filter and cleaned the snow screen. i also cleaned the egr,intake,and turbo vanes.

 

[onetwo]

any ideas?

 

[Ol'Rattler]

You could try diagnosing the problem. The pretty graphs tell you what is happening, it's up to you to figure out why. Can you display requested versus actual boost? (Group 11 in the measuring blocks)
https://www.myturbodiesel.com/wiki/...roubleshooting-vw-seat-skoda-audi-tdi-engine/

 

[onetwo]

group 11 is the 3rd graph i posted, blue line is requested and red line is actual boost.

 

[Ol'Rattler]

Thanks for you patience. I'm learning about this stuff myself. I appreciate the opportunity to further my knowledge. I'll try to graph my healthy turbo's to see how close to actual and requested the numbers should be. My assumption is that your actual and requested should be closer, but at this point IDK.

Try basic setting in group 11. It will run a test that revs the engine to 1400 RPM's and cycles the VNT actuator. The low number is basically 1 atmosphere and is represented in Millibars. Generally, one atmosphere = 14.7 PSI or 1013 Millibars. You get that same number with the engine not running. (1 atmosphere)

With the engine running the test cycles the turbo actuator and the difference between the non boost and boost numbers should be about 80 to 260 millibars. If the high number is considerably higher than the lower number, the turbo will over boost under load and could cause limp mode.

 

[onetwo]

Thanks for you patience. I'm learning about this stuff myself. I appreciate the opportunity to further my knowledge. I'll try to graph my healthy turbo's to see how close to actual and requested the numbers should be. My assumption is that your actual and requested should be closer, but at this point IDK.

Try basic setting in group 11. It will run a test that revs the engine to 1400 RPM's and cycles the VNT actuator. The low number is basically 1 atmosphere and is represented in Millibars. Generally, one atmosphere = 14.7 PSI or 1013 Millibars. You get that same number with the engine not running. (1 atmosphere)

With the engine running the test cycles the turbo actuator and the difference between the non boost and boost numbers should be about 80 to 260 millibars. If the high number is considerably higher than the lower number, the turbo will over boost under load and could cause limp mode.

here it is :

 

[onetwo]

heres a log of me cruising around town, the red line (actual boost) is always higher than the blue line (requested boost).

 

[jollyGreenGiant]

You have a mechanical fault with the turbo's control system. The ECM is telling the N75 to do stuff but it doesn't appear that the actuator is doing anything in return.

 

[eddieleephd]

looks like you need to adjust the actuator to get the overboost down to normal boost.


Because the difference between the red and blue lines are consistent it is a lever length issue.


basically the arm is too short I think and not closing all the way.


I had turbo issues a while back and ended up with a VNT17 as the original turbo had the worn VNT syndrome and would stick open.


New turbo and actuator was the solution for me.

you might be able to get the actuator adjusted thought.

remove the actuator lever and move it all the way, open to close, and see if you feel any not smooth movement.
mine would stick open, however, it never threw a code or went into limp mode.


When I did install my new turbo is when I had the issue similar to yours where I had to adjust the actuator to get it within 200HG of requested, within 500HG I believe is acceptable.


Yours seems to be right around 550 to 600 consistently which is why it's throwing limp mode.


And the cruising graph is no help whatsoever, pull another reading like the third after doing an adjustment.


I had to adjust and drive multiple times logging in between, twice to know I was adjusting the right way, and multiple more to get it right.


https://www.myturbodiesel.com/wiki/...ustment-repair-replacement-on-tdi-engine-mk4/

 

[onetwo]

looks like you need to adjust the actuator to get the overboost down to normal boost.


Because the difference between the red and blue lines are consistent it is a lever length issue.


basically the arm is too short I think and not closing all the way.


I had turbo issues a while back and ended up with a VNT17 as the original turbo had the worn VNT syndrome and would stick open.


New turbo and actuator was the solution for me.

you might be able to get the actuator adjusted thought.

remove the actuator lever and move it all the way, open to close, and see if you feel any not smooth movement.
mine would stick open, however, it never threw a code or went into limp mode.


When I did install my new turbo is when I had the issue similar to yours where I had to adjust the actuator to get it within 200HG of requested, within 500HG I believe is acceptable.


Yours seems to be right around 550 to 600 consistently which is why it's throwing limp mode.


And the cruising graph is no help whatsoever, pull another reading like the third after doing an adjustment.


I had to adjust and drive multiple times logging in between, twice to know I was adjusting the right way, and multiple more to get it right.


https://www.myturbodiesel.com/wiki/...ustment-repair-replacement-on-tdi-engine-mk4/

I'm back trying to fix my problem, threw a new n75 valve.. still over boosting..I'm going to look into adjusting the actuator rod length..I checked the operation of the actuator it does begin to move at the right Hg and it stops @18hg.

Say the rod length had been tampered with, the actuator is still going to start moving and stopping at the same vacuum correct?

 

[eddieleephd]

Yes, the actuator will begin moving and stop moving at the same vacuum levels.
The length of the rod is going to depict what boost you have total and that's it.
I never liked the method people used to say when it should start and stop.

I log and adjust until I have it right. Gets hot, but, you just have to deal with it. I found using a wrench and 90 needle nose pliers to k it from binding essential.
Using a vacuum pump to take the pressure of the rod helps to adjust it in the easiest many possible so you're not fighting. Pump to take the pressure of, plug line back in tighten nut and log
Sent from my Armor_2 using Tapatalk

 

[onetwo]

Thanks for clearing that up for me. So a need to add a little length to the rod, how many turns does it take before you start seeing a difference?

 

[eddieleephd]

You'll start seeing it immediately. I usually do 3-4 partial turns, what yo can each try, and log to see what happens

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[Franko6]

Adjusting the turbo actuator rod is more science than 'giving it a turn or two'.

When adjusting the actuator, use a vacuum gauge like MiteyVac. plug the equipment directly into the vacuum pot and watch the actuator as you apply vacuum. The actuator arm should start moving at 4-5 in. and should be against the stop screw at 18 in.

Also, you should check to make sure your pressure converter (N75) has the proper vacuum at idle. The top line should be pulling at least 27 in. The line going to the actuator should be at 18 in.

Agreed, there is a spike difference between the actual and requested measurements from you MAP and your ECU. Sure, it could take 'a couple of turns', to correct the difference, but I'd rather do it with the methodology that is accepted and common practice.

Besides, what if it's your N75? You'd be screwing, literally, with the wrong thing.

 

[eddieleephd]

Doesn't matter what you do, the actuator will start moving at the same vacuum, blah... The truck is getting the turbo veins to stay moving then and that's not as easy with the turbo installed.
I really had no luck adjusting the boost with the listed method and will never find it useful unless I have the turbo of and am doing a fresh install.

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