I am having an issue and was hoping that I might get some suggestions. Here is my problem. I am unable to build boost above 12psi. Boost response is also very poor. At 4000rpm I have about 7psi, at 5000rpm I have about 9psi and then it maxes out at 12psi at about 7000rpm (measured with both my boost gauge and my AEM EMS). Here are the things I have done so far to try and figure out the issue and none of this changed the above readings.

1. Checked for boost leak using tester and compressor. Pumped it up to 25psi. Used soap and water, looked for bubbles. I have one very small leak at my BOV but that is not the issue. For it to have this big of a problem the leak would have to be massive.

2. Disconnected MBC from the actuator to make sure that there was not a problem with the MBC.

3. Checked the actuator with air pump to make sure that it works (it does).

4. Disconnected the actuator from the waste gate, wire tied the waste gate shut.

At this point I am wondering if it is a problem with the turbo or the waste gate. I have hand spun the turbine and it does spin but I am not sure how freely it should do so. I also pulled back and forth and up and down on the center of the wheel to see if I have any bearing play, there is very little movement so I do not think that is the issue.

 

Sounds to me like you are missing the pill between the wastegate and the compressor housing check to see that you have that pill in. My car did this for two months before I could figure it out.

 

The pill isn't an issue when he has an MBC.

My questions are...

1) How did you boost before this? ~20psi with no problems?
2) If so, did any variables change between the previous condition and the current condition?
3) If so, what were those variables?

 

He has a MBC so there is no need for the pill.

 

Try pulling off the vacuum line from wastegate and see if you can hit 20psi. Becareful not to hit 30psi though. If you can't then you have a wastegate/turbo problem.

 

you can also try taken ur exaust off i had a bad cat and t made soo much back preasure i couldnt make any more then 2 psi and it slowly came to be ... any way try just taken the two bolts that hold ur down pipe on and go for a spin.


you can also take off your intake and make sure the turbo has little / no shaft play and that it spins freely

 

my car is at the shop right now with the same story.
I get eleven to 12 psi. Slight mis at 6500 rpm too.

chinto, So you say it might be the cat? you must have had other drive-ability problems too(?).