Ok... here's what's going on....

The car just came out of a rebuild a few months ago -- still isn't working right.

Boost -- about 4psi.
When revving at about 6000 RPM (any gear, any amount of throttle), the car starts feeling like it CAN'T rev any faster... and it fact, it stops at about 6000.
Here's an example: in first, gun it... it starts revving up and moving... as it hits about 5900-6000, it starts "stumbling" and in fact, you actually feel a sudden loss of power. it hits about 6000-6100 RPMs and it just stops revving any faster.

Any ideas?

 

so how many miles on this rebuild ???? We'll figure you've run it in. Broke in may fit better here we'll have to see.

 

clogged cat? fuel filter?

 

Here's some new info on this situation...

Now, the car revs up fine to redline -- NO CHANGES WERE MADE since I first posted this on 9/7!

Second, before the car has been driven for a while (i.e. warmed up, but maybe within the first 10-15 mins of driving), the car boosts up to about 10-12lbs... after some time driving (say 30 mins or so), the boost goes only to about 5-6lbs...

Any ideas?

Caught a small crack in the exhaust manifold cause this much loss in boost? The mechanic that did the rebuild said he saw a small crack in the exhaust manifold and he swears that fixing that will fix all my problems....


Note: here are my "power" mods:
DP, catback, center pulley, open intake, automotive FPR, M2 stage 2 ECU

btw: along with the rebuild, the fuel filter was replaced....

thanks!

 

Two major possibilities:
1) A boost leak that happens when the part gets hot (and soft) enough. Also an intake pipe could be collapsing that causes an intake restriction - again, when the bay is hot, the plastic pipes get soft and more prone to collapse.

2) A solenoid that fails to perform when warm or hot. This is tougher to pin down, although the bad part will run under $100. One strategy is to tee your boost gauge into the line coming from the solenoid and monitor it to see if it's producing the same output both when the car is boosting right and wrong (then repeat said test with all turbo control solenoids). The other strategy is to remove the UIM and rats nest and test every solenoid. I'd be happy to support you in either effort.

Most turbo manifolds have small cracks where they meet the exhaust manifold. It generally does NOT affect boost. The fact that you sometimes get 10-12psi indicates the crack is not the problem.

Do you still have the stock cat?

 

Yes, I still have the stock cat on... I figure when it's "dead," it will be replaced with a hi-flow one....

Is there anyone that's really good with RX's that's local to me that knows how to do and look for what dgeesaman is suggesting? I'm in Northern New Jersey... Morris County to be exact...