Compressor surge / waste gate flutter??? Need help.
 

Hey all,
I have an 08 Evo X and I recently put windows in the block. I decided it was time to upgrage. Bought a long block and upgraded the rods, pistons, bearings and headstuds. Also picked up a Garrett GT3076R turbo configured for stock frame fitament with the smaller compressor housing (designed for the X). Just got the car tuned at Boostin performance in Hoffman Estates, IL. After picking up the car I have found it is almost impossible to drive. It will cruise at a given speed smoothly and WOT is also fine but anything inbetween is a nightmare. The car bucks and studders with any amount of throttle especially at highway speeds. Light throttle produces bucking constantly and heavy throttle (not wide open) I can hear the BOV purging several times in rapid succession. The car could only be tuned to 29 PSI and at that point the waste gate duty cycle was 100% according to the tuner. he could not get any more boost out of it. I have been told to replace the BOV and also possibly upgrade the waste gate actuator spring pressure. Supporting mods are :Synapse BOV, Greddy EBCS, AMS 3.5 in. intake, Map performance UICP and LICP, 3.5 in. intercooler, tubular headers, full 3 in. exhaust all the way back to a magnaflow muffler, no cat, Megan racing O2 housing, Invidia down pipe/test pipe combo.
I really need to figure this out. I want to get rid of the bucking and jerking but I would also like to get more boost and power out of the mods which the tuner said is being left on the table because of the configuration. Any advice will be welcomed. Thanks.

P.S. Yes the entire fuel system is upgraded sufficiently. Didn't think that was relivant so I didn't add it.

Take Boostin's advice. I'm guessing Devin tuned you? They're very capable over there, and know your vehicle better than anyone on this forum would at this point.

Why don't you just let them know the car is hard to drive im sure they could adjust it to make it smoother.

I did. Just came from there this morning. They said there is nothing they can do.
Forged bottom end, GT3076R turbo 375hp/329tq on a mustang. They even said they couldn't get the boost over 29. I was at 29 psi on my stock turbo before the upgrades. Something is not right. I just need to figure out what it is. And I don't have unlimited resources to throw at it to find out.

Boost has nothing to with drive ability. Was a boost leak test performed?


How is the synapse BOV setup?

I agree with that to a point. Boost itself does not but how that compressed air is released back into the intake system can. Or is that not a correct statement?

Yes they said they did and I paid for a boost leak test.

The synapse is setup to recirculate and both A and B ports are connected to vacuum. Its also in a push configuration meaning the boost is pushing the valve closed and vacuum opens it. Anything else I missed?

No, it's not. The bov opening dumps the charge, so the car loses power. When it flutters, the car gains and loses power rapidly.

Do you have the stiff or soft spring in the synapse?