Boost creep problem
On DSM's the wastegate hole was too small, which caused boost creep. The solution was to open up the wastegate flapper opening. The more advanced twin scroll setup with the 10.5 housings, have a much larger flapper opening, so that is not required on the Evo 10.5 turbine housings. Dont waste your time on that.
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From: Taftville, CT
Yeah, I hope that you can fix the problem by getting your EBC to relearn the altered boost curve. That would be the easiest solution.
I went back and reread your original post and see that you still have the stock cat and the stock O2 housing on there. I don´t see how your exhaust could be way too free flowing if it still has these 2 major restrictions in place.
So, maybe you are right and it is your EVC not relearning the new boost curve. If you were to disconnect the EBC and install an available MBC just for test purposes you might be able to narrow down the problem.
If you do have to port your turbine housing, then focus most of the grinding attention on the initial turn in radius from the main scroll area into the WG bypass port(hole). You can openup the bypass port itself leaving about 3/16" of the port radius for proper puck sealing. This is with the single flapper 10.5, I am not that familiar with the double flapper 10.5 hsg.
I went back and reread your original post and see that you still have the stock cat and the stock O2 housing on there. I don´t see how your exhaust could be way too free flowing if it still has these 2 major restrictions in place.
So, maybe you are right and it is your EVC not relearning the new boost curve. If you were to disconnect the EBC and install an available MBC just for test purposes you might be able to narrow down the problem.
If you do have to port your turbine housing, then focus most of the grinding attention on the initial turn in radius from the main scroll area into the WG bypass port(hole). You can openup the bypass port itself leaving about 3/16" of the port radius for proper puck sealing. This is with the single flapper 10.5, I am not that familiar with the double flapper 10.5 hsg.
I just got back from relearning the evc, no more boost creep.
I'm going to be in the market for a new ebc, something with adjustable wg gain. Any suggestions?
I have the HKS EVC4 on my Z and almost everytime I make a major modification to the intake side or exhaust side I need to recalibrate the base boost setting. I bet if you turn your EVC off and "floor" it your base boost is higher than what it was prior to the modifications that you recently made. Try adjusting your base boost and your base boost plus settings before you do anything radical.
The biggest restriction (cat) is already taken out ... I was under the impression that by the time the car hits higher RPMs (over 5000) the wastegate is fully open ...
Sounds like maybe your wastegate is preloaded too much, that is if you're still on the stock wastegate. When I run purely on wastegate pressure I only see a peak of around 14psi.
Actually the only BC that would have adjusted for this would have been a MBC.
That is not boost creep. That is a malfunctioning or improperly setup boost control system. Boost creep is caused by a physical limitation of the turbine housing wastegate system to bypass enough exhaust flow to control the speed of the turbine shaft. That was not your case. It works with the wastegate actuator alone, so that means the wastegate system is working properly.Brian
well I am having a similar issue. With the weather being pretty cold here in jersey, 1-3 hold 21psi like a rock. hit forth, and as you get past 5k and up twards 6000-7000 the boost just keeps going to 24psi. and holds. It is as if, 4th gear makes full boost (21psi) and holds a split second then starts to go up from there. No idea here. I was wondering if it coudl be caused from the filter I am running in conjunction with the cold. I never had this problem before the really cold weather came in
........ That is not boost creep. That is a malfunctioning or improperly setup boost control system. Boost creep is caused by a physical limitation of the turbine housing wastegate system to bypass enough exhaust flow to control the speed of the turbine shaft. That was not your case. It works with the wastegate actuator alone, so that means the wastegate system is working properly.Brian
That is not boost creep. That is a malfunctioning or improperly setup boost control system. Boost creep is caused by a physical limitation of the turbine housing wastegate system to bypass enough exhaust flow to control the speed of the turbine shaft. That was not your case. It works with the wastegate actuator alone, so that means the wastegate system is working properly.Brian^^+1+1
+1+1^^. Sharp diagnosis by TURBODAWG. Exactly!well I am having a similar issue. With the weather being pretty cold here in jersey, 1-3 hold 21psi like a rock. hit forth, and as you get past 5k and up twards 6000-7000 the boost just keeps going to 24psi. and holds. It is as if, 4th gear makes full boost (21psi) and holds a split second then starts to go up from there. No idea here. I was wondering if it coudl be caused from the filter I am running in conjunction with the cold. I never had this problem before the really cold weather came in
Brian
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