2005 turbo S.
New Switzer turbos
DVs are good
5 bar fpr
1 bar wg springs
EPL tune.
Backpressure checked and good
Wastegates wired closed and car still won't make more than about .9 bar of boost. Tune is commanding 1.3 bar.

Can somebody give me some ideas for other potential problems?

PS: its not the turbos because I had the same problem with the K24s.

Thanks

 

Boost leak? Fuel pump problem?

 

are you getting any codes?

try replacing your N75 valve and checking the vacuum and electric connection to. its only 25$ and that is what controls your WGs.

pressure test for boost leaks.

replace intercooler hoses O-rings

 

Smoke test for leaks

 

I had a similar problem with my car. It turned out that I needed to manually adjust my wastegates since there were no boost leaks to be found. Not saying this is your issue but it could be a good solution (last resort). I marked mine with touch up paint to ensure the proper adjustment on each side.

 

I would start with a smoke test. Make sure you check the intercoolers when smoking, I had the smoke coming out of the duct by the pass. door. If all that is good clamp the line that feeds the DV's, be careful if you have the wastegates wired shut like you stated or you will over boost and be in worse shape.

 

pressure test from the turbos...smoke tests will not find all the issues... pressure test to lets ay 25 psi from the turbos...
get your Wg checked and see if they open at 1 bar... and are they equal...
make sure both turbos are good... check the compressor make sure the wheel is not hitting the housing... run a log on durametric... log rpm, engine load, ignition angle... qxugen sending actual lamda bank 1 and 2.... boost pressure of sensor and set point boost....

boost pressure of sensor and set point boost.... this will tell you what the ecu is asking for and what its actually doing....
good luck,
markski

 

Thanks for the advice guys. I should have mentioned in the original post that the intake has been pressure tested up to about 2 bars, and my shop also replaced the MAF sensor. Sounds like I need to try the smoke test and replace that N75 valve next.

 

Nope, no codes.

 

Dude if the wasgates are wired closed and you are not making boost There is only a few thing it can be. turbo's too small, nope. boost leak? either to atmosphere or threw the DV's. Or hurt turbos, look at the compressor wheels like Marski said.

 

The turbos are brand new, and I had the same problem with the stock K24s, and the DVs have been checked, and the system has been pressure tested with no leaks found. I wish it was that simple.

 

Is the engine running smooth? If not it could be fuel supply?!

 

Blocked or too restrictive exhaust system?

 

I would do the next thing Markski suggested - durametric log and see what boost is being requested by the ECU. If it does not match then start looking at problems. If it does match, then maybe a software issue or limp mode?...

 

checking the dv's and them works proper are two different things. when I was using stock type dv's the vacuum line that feeds it was leaking and I was only able to make .9 bar of boost on gt3076's. BTW brand new turbos does not mean that they were not damage while being installed. Are you doing the work yourself?