I've tried nearly EVERYTHING.

I've turned up my MBC all the way, tried 2 different mbcs, tried tapping into BOV line and have also went straight to the turbo nipple. I've tried every port combination on my synapse synchronic dv (A, B, A+B) and many preload settings (none, one turn, three turns, max, etc) All with the same outcome... no boost past 29 psi

I did a boost leak test today and here's what I found :

Hissing/leaking noise coming from throttle body. After reading the OP in this thread https://www.evolutionm.net/forums/ev...g-how-why.html it looks like that is normal.
"There may be audible hissing at the throttle body. One cause is air passing through the idle air control valve. That hiss should change in tone or almost disappear if the throttle plate is opened manually."

Also sprayed the DV and bubbles rapidly formed/popped from the port/fitting side of the DV. I teflon wrapped the fittings and tried again. Same result. So it looks like the synapse DV is leaking a little bit but I don't see why that would make it so I cant go past 29 psi...

I'm out of ideas.... is my stock wastegate maxed out? E85 on stock EVO 8 - 10.5 turbo

 

i would say if you have a hissing at the TB you have some shaft seals leaking some. Also that along with a small leak from around the BOV would keep you below 30 psi. I think the stock turbo will spool like ~32 psi? So if you have to leaks that would be the culprit. Mine does about 30.5 with the MBC fully open.

 

Thanks... also not really sure if this matters but the air compressor wouldn't go past 25 psi. Would that also be because of the leak?

 

usually i just put about 15psi in the system or 20 at most because i am just asking for the tester to come out and smack me in the teeth lol. I have everything around the BOV zip tied along with a clamp. Also have the MBC routed to the turbo outlet nipple and then tee'd into the BOV. At that high boost any small leak will hold you back a few lbs

 

Shouldnt you be testing up to whatever psi you'd be using in the real world though? That way the leaks actually show up.

 

yeah ideally but i could never keep the tester on at 30psi. I don't have a peep out of anything.

 

So the throttle body shaft seals are most likely leaking. Its probably not the idle air controller valve thing by it, right?

 

A lot of people have issue with the IAC teeth coming off causing idle issues or just failing electronically. Some people have it leak but a huge problem with evo's is the TB seals. Mil Spec makes aftermarket seals that hold boost a lot better. I have never had mine leak and to my knowledge they are stock. So i guess it depends on the car. But i think they are 20$ if you do it yourself. I mean even a small leak is still effecting performance. If the hiss changes with movement of the throttle then its the TB seals.

 

Gotcha. Ill be ordering shaft seals tomorrow so ill post results up by next week. Thanks for the responses.

If anyone has any experience with the Synapse Synchronic DV's fittings leaking please let me know!

 

Good luck man keep us posted. I think there are 2 or 3 companies who make aftermarket seals so just search it and decide.