Ok so here's what's going on. I installed a 3 port on my friends mr tonight. I set up the gear dependent boost so 1-4 are low and 5-6 are high. I've got low gesr set damn near perfect, however 5-6 is the problem. If I'm on the highway and give it 50% or more throttle is bucks really bad and I hear the bov venting. Almost like its leaking so I crushed the stock bov and same problem. I've tried turning the high gear boost down and still same issue. I swapped in a green relay and still the same. Ive logged the tps and it stays wide open while the boost looks like a jagged line. he had a mbc before and never had this problem. Car has an intake, uicp, exhaust. Stock turbo. Hmm I'm trying to think of anymore important info.

 

changing to a 3port usually requires a tune

 

Umm yes I'm aware of that. Anyone else have any ideas? Seems its doing it as wel when I'm about 50% throttle in lower gears too. It's as if the throttle is opening and closing really fast. I hear the bov fluttering. It's a stock crushed bov. It has an open filter that is shielded. I'm really stumped. Should the wgdc maps resemble the ones in the Merlin tuning guide or stock and just lowered?

 

Well, since it appears that you are the one tuning this once it was installed, maybe have a mod move this to the Tuning sub-forum instead of General, as that way the right sort of eyes will see it and can assist.

As far as non-tuning assistance have you double checked the lines and fittings on/around the 3port. Make sure nothing is defective. Have you been able to use a pressure gauge and a pump to verify the 3port is operating without issues?