Ian928

Just in from the garage after changing the recirculating valve to a Turbosmart valve. no change in boost I am sad to say. I guess that means I need to look at the exhaust side...

PEvans

If the signals to the ECU get garbled, due to a bad connector or loose wire, the ECU will go into "limp" mode, limiting the boost. On my car in limp mode the boost stops at just past the 1bar mark on the gauge.

Ian928

If I remember correct all of this was removed when we installed chips and Manual Boost Controller. The ECU still have control over ignition and fuel, that may reduce power but maybe not this much?

I am planning to open the CAT and see if it is possible to replace it with a straight section of pipe. What pipe diameter is the exhaust?

Ian928

I did some searching on this forum and found the horror pictures of the collapsed inner pipes! The car did have a irritating rattle that has now disappeared. I always thought that the rattle had to be from the cat, but I see that it might be from the inner pipe. Does anybody have a idea of frequency for collapsed pipes before and after turbo?

I see the complete "test pipes " are crazy expensive, but if a bolt on pipe solve the problem then that may very well be the solution.

Ian928

The price on this site seems very low compared to other placed, can anyone confirm this is legit?

https://porsche-parts-store.myshopif...eed-203-20inch

Ian928


This weekend I fitted a Fabspeed CAT bypass. I also used a boroscope to check the 90 degree downpipe and it was clear.

I still have very low boost. So what now? Change wastegate?

Thom

What sort of MBC are you using?

black944 turbo

How are the vanes looking on both sides of the turbo? How is the shaft play? It could be the crossover or wastegate as well.

Ian928

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i do not know, but I have tried to pinch the hose after the MBC and that did not change anything.

Ian928

I was just able to pry the J-tube off and check the Vanes and play, felt good. I checked the vanes with the boroscope from the exhaust side and saw nothing wrong.

Dan Martinic

One time, it was winter, I was driving along and decided to accelerate rapidly. The boost started building then immediately cut off; it felt like hitting something for a second. This kept up for short time. After filling up the gas tank, it stopped doing this and all went back to normal.

I have no idea what happened other than possibly the knock sensor reacting to some bad gas (and actual knock). Not that I even know or have heard what knock really is. But, you never know: maybe there's something up with your knock sensor or KLR unit.

Wait--I just realized that the KLR limits boost by controlling the boost controller, something you've replaced with the MBC. Ooops

On a side note... I have to admit that I too now have an MBC and kinda wish I kept the stock controller simply to have this knock-boost protection

black944 turbo

Check for vacume leaks. Check the wastegate. Have you tried to pinched line to the wastegate? If you do this, be very careful.

Mike Goebel

Click here --> I got the same sorta problem.

Thanks
Mike G.

Dan Martinic

Hey folks.. if you have the wastegate out, can you reliably apply incremental psi to the top fitting & check when it opens, testing for weak springs?

Mike Goebel

Yes!
you either need a nice regulator on your compressor or a hand pump type with a gauge.

4-6 psi to open
10ish psi fully open

Mike G.