997 tt/rs

Hi Guys,
I noticed 0.15 bar less boost which is now 0.7 instead of 0.85 bar boost.
Everything seems to be in place, the o-ring between the throttle and intercooler was replaced but unfortunately it didn't change anything. All cables are connected. Blow off value also seems ok. Any idea where to look next?
Is it possible that the plastic manifolds between the heads and the intake manifold have leaked?

thanks a lot !
k

TMWTP

I've been chasing boost loss for a long time. Finally determined my wastegate is leaking. First step was to plug the boost line between the intercooler and turbo. Be careful of overboost! It made 1.2 bar (1 bar spring). Next, I removed the plugs and put a mityvac on the line. It would not hold pressure. Final test was to put smoke down the line into the wastegate, which showed smoke coming out the tail pipe.

Otherwise, check the usual suspects of vacuum leaks, exhaust leaks and fuel control pressures.

997 tt/rs

Thanks a lot for your input !

Nyx

I rebuilt mine with this kit

Was awesome

https://www.performanceenginerding.c...rue&cst=custom





Froze the guide and heated the body. Dropped right in.

Measure the valve stem to make sure it’s in spec.

fritz k.

The original wastegates on our cars are all slightly leaky, at the valve head, at the valve guide and worst case the diapragm. In the case of the valve head, this means that part of the exhaust gas is discharged through the left exhaust pipe in front of the turbocharger. Some exhaust gas energy is lost, but usually not so much that the result would be a noticeably reduced boost pressure.

With the leaky valve guide, boost pressure is lost from the control line from the intercooler to the lower chamber of the wastegate. This means that a small proportion of the boost pressure is usually lost, but overall it tends to increase because the wastegate opens later then.

Regarding the wastegate i prefer a solution with a measuring instrument to monitor the boost pressure and the possibility to vary the pressure in the lower chamber of the wastegate continuously. This way you can adjust the boost pressure as you like and compensation of wear on the wastegate mechanics is a side effect.

To find the cause of the pressure loss, a smoke machine is very helpful.

Fritz