I'm not at the shop now. As I recall there's one 6 mm hex head screw with a 10 mm head that has to come out. Then you have to give it a good pull but be careful there's a wire to the mass air flow sensor. That cable can be tricky to disconnect since it has the typical Volkswagen quick connect. Go online look how to disconnect Volkswagen quick connects. There are different ideas. Anyway I have my way which I can elaborate on later if you need help.

Also disconnect the PCV connection at the intake manifold. Be gentle the plastic inside this tube is fragile and cracks. Then you have a vacuum leak. Should that tube crack there's a way to fix it but be gentle, nonetheless.

 

The air box just needed a firm tug to come off. I can take more pics if necessary.

 

The turbo impeller looks good. Worthy onf inspecting the other one.

See if it's possible to get independent results from each turbo.

Through vcds, find a way to test the solenoids above the transmission that control the turbo wastegate vacuum.

There are two diaphragms on the turbo one is for the wastegate, the big one. The other is the little white plastic in the image with a small vacuum line, not sure what this does.

Internal diaphragm failure would cause overboost to happen.


The previous evaluations were not in vain they point towards deeper analysis. The situation highlights why it gets so expensive at a dealership. They are faced with the same problem and it gets very time-consuming.

From this standpoint even if pulling the engine took 2 hours which it doesn't, what's next? Hopefully someone out there has had a similar experience and can throw out a few thoughts.

The Assumption is the car other than this overboost condition

runs well and not symptomatic of main vacuum line leaks?

[Sorry I inserted the photo in the wrong place. Don't know how to move it so there it is].


Let's make this a group effort, and figure out what's ailing this car.

 

Being a 2007 there's a possibility the wastegate solenoid I'm referring to is behind the engine under the steering rack. Above I mentioned on top of the transmission. If not mistaken 2007 was a transition year for that design.

 

I really appreciate your help. I am going to try a few more things and then probably just try to find a good indy in Sacramento and pay them a diagnostic fee. But, like you said, finding someone to diagnose this correctly without spending many hours is easier said than done. I will look at the other impeller. I have not smoke tested it, so a vacuum leak is possible. The reason I was assuming that the cause is not a severe vacuum leak is that my fuel trims look fine at idle and I have no other codes.

My only possible idea based on what we have found so far is that there is so much oil in the intercooler fins on the driver side that it might be creating a big enough restriction to cause this (but I really doubt that it is a big enough restriction to be the entire problem).

This is my plan: 1) Log the other turbo. The one I did is module 01 (which is the main ECU). I logged 115 while in that module to get the boost. I believe if I log 115 in module 31 (the other ECU) I will get boost for the other turbo. I do not know which is left or right, but I can probably figure that out.

2) Test in VCDS. I know I can test some of the solenoids and other components in VCDS, I am just not sure which ones or how. I did find instruction for some of these tests for Audi and VW, I will try those and try to figure out how to do more.

3) Indy. If it is not figured out by this point I will start trying to find a good Indy in Sacramento.

 

Save that thought on the oil in the intercooler.

Removing the engine compartment intercooler hose on the driver side and likewise the lower one which you just disconnected and reconnected. Use in well-ventilated area, chlorinated brake cleaner and air pressure from the top and blow that sucker out. Don't risk going through all this have Indie tell you have a clogged intercooler.

Still in the realm of cheap. Worth a try.

 

I cleaned out the intercooler and put everything back together. Unfortunately, the only way to measure the boost on each side that I could figure out in VCDS would not allow me to log any other values simultaneously. A second gear pull with both sides boost values is posted below. The beginning looks a little strange because I was on a turn and there was a little traffic so I had to back off the throttle for a second. The data on the left is the same side from the previous data (I am guessing the driver side, but I am not sure). The data on the right (the side we have no seen before) looks better to my untrained eye. It looks to me like there is a blockage on the side we originally loged, but the other side might be ok. I will test some more things with VCDS tomorrow. I can log data for N75 boost controller and I think I will be able to test it and some other components.

 

Stick with it. You'll figure it out. Why pay someone 100 plus dollars an hour.

Been there done that.

 

 

Did you manage to get anywhere with this?

I am experiencing a similar issue, around 4k RPM boost cut and over-boost DTC.

 

Despite 1eapplebaum’s help I never figured this out and I never had a chance to get back to it since returning from vacation. I do not remember exactly what this was called, but I was able to do some king of function tests in VCDS. I did the same tests on the bank that is overboosting and the one that is not. I tested every turbo component I could find there and everything sounded the same on both sides. I am out of ideas and I think I will just look for a good indy in Sacramento when I get a chance.

 

I saw the Bentley from 2008 up Speed model
I saw the turbo doesn't has the solenoild on top of the waste gates?
As I heard the solenoid can't separate on the old one and the waste gates is not a standalone unit to repair.
Are there anyway we can fit the Non electric version in the old one.

 

There is a diverter valve n249. When this unit malfunctions it can cause overboost. The turbo Audis and Volkswagens use the same component. Reading up on this leads one to believe that could be the problem.

In any event hopefully the problem has been fixed.

 

Does anyone know how to do an "output test" or otherwise function test the wastegate? I think the problem may be a seized wastegate or a ruptured wastegate diaphram.

I was able to do an output test test on the n75 and the n249. I think they are both ok. Plus the n249 just controls the diverter valve, so while it could throw a p0234 code I do not see how it could produce my symptoms (no power/feels like an exhaust restriction) at higher RPM when I am staying on the throttle.

If I can not figure out how to test it I was thinking it may be possible to put a camera in there and see what it does when I drive. I am almost out of ideas, but everything seems to keep leading me back to the wastegate.

 

The way to check the function of the wastegate is with a vacuum pump .Under the car where the diaphragm silver housing barely sticks out, there is a small vacuum line attached to the back of the silver wastegate diaphragm. Attach a vacuum pump to that line and see if the wastegate retracts. This is a tight fit but doable. The plastic belly pan will have to be removed to access this area.