NefMoto

Hey, looking for possibly a little insight into an issue I'm having. I just installed a brand new Stock Borg Warner K03 into my 04 A4 1.8t and now it's getting overboost code. I can feel it dramatically build boost at low rpms, then I can feel the car kicking the boost down suddenly and dramatically at around 3500 rpm.

Now, I JUST installed it and finished up late last night, sooo, I definitely haven't tried troubleshooting anything yet.

Obviously this new turbo is quite a bit more efficient than the worn out one it replaced...so the first thing I would like to try is maybe "resetting" the ECU to relearn the new turbo?

Question is, does anyone know if there is a VCDS procedure to accomplish this...or just disconnect the battery for a bit?

I verified with the vendor that the wastegate on this new turbo is factory set to 5.4psi at 4.0mm travel.

I have not looked too deeply into the possibility of a boost leak on the N75 yet, but will do so this evening.

The ECU doesn`t "relearn" the Turbo. If you cleared any preivously codes and every time you go for a spin you got an Overboost DTC then you have a problem.

1)Maybe it is software ( tuned to your previously  worn out Turbo as you said)
2)Maybe your WG is cranked up
3)You did something wrong when installing your new Turbo

I would first connect the charge pressure line and waste gate line together eliminating the n75 (cap off n75 ports so  and see what she boosts.

If its boosting 5.4 then you know your wastegates good if not either bad line, bad wastegate, wastegate is hitting something and not opening there could be alot.

Post your results i fix these issues daily.


Charge Pressure         Waste Gate
===========>()<============

Thanks for the reply.

1. Stock software. Stock Turbo.
2. Shouldn't be, Borg Warner new from factory. (But will check)
3. Pretty hard to do. (Would probably result in a bad boost leak and low boost if anything)

I appreciate the response.

Yeah, that would be a for sure check of the wastegate. I will probably try that. Unfortunately, it's a pain dealing with those stock hose clamps and cramped area around the N75.


Only thing I forgot to mention is I'm catless. Don't think that would really cause a significant difference...do you?

you can simply unplug the N75 electrical connector
its not so accurate like vdubnation`s way, but in most cases it works the same

Only reason i ve done it that way is had some nitemare n75s crazy symptoms so i just do it so in the back of my mind i dont have to worry about anthing else.

Yeah, I was actually just contemplating that...


Does anyone know if the ECU uses the N249 valve to manually recirc boost on an "overboost" condition?

No. It will close throttle instead.

I'm betting you have a torn wg line.

Why was the turbo replaced?  Did you have over/underboost codes previously?

Make sure you didn't pinch a vacuum line by the n75 or turbo, seen that a few times.

(http://www.desismileys.com/smileys/desismileys_4547.gif) (http://www.desismileys.com/)

I'm going to pressure test tonight.

The old turbo was boosting okay...a little weak. Main reason for replacing was I bought the car broken kinda...one of the issues was a clogged/collapsed cat that was getting extremely hot and caused stress cracks in the turbo exhaust housing. Wanted to replace before something catastrophic happened.

I will check the lines.

And the wiiiinnnnnnnneerrr iiiissss...BDK!

I started poking around by the N75 after doing a pressure test (having satisfactory results) and noticed that the charged line from the turbo to the N75 was pinched right after the banjo bolt. Adjusted and perfect!

Thank you for all the brainstorming everyone!

glad you find it ! start using silicone hoses :)

P.S. why does this guy has so negative rep ?!? ???

Thanks! I will eventually start moving to silicone.


P.S. Because I asked too many questions earlier on...