SR20DET Losing Boost

[240sxConvert]

I just swapped in my SR and when I hooked up the boost gauge, it was only boosting 5 psi. I wanted to raise it and so I bought a Manual Boost Controller and raised it to 10 psi. When I get on it, it boosts at 10 and then slowly goes down. It was not doing this before. I also noticed that in 4th and 5th, it stays at 10 psi. I have checked for boost leaks and I am wondering if I just need to get a FMIC because I am running the SMIC right now. Any input would be greatly appreciated.

[Gramentz]

I'm guessing that the boost drop you experienced at 5psi is either the wastegate or a boost leak. Double and triple check to make sure all couplings are tight. What kind of boost controller do you have? I bought a mbc once that leaked on me. It would hold 12 psi for a while, and then it would slowly drop down.

[240sxConvert]

It's a Voodoo MBC. Cheap! Like seven bucks or something. It was boosting 5 psi fine with no boost controller. When I put it on I set it to 10 psi and then it would slowly leak down but not in 4th or 5th gear...it would stay steady. I lowered it to 8 psi and it does the same thing. I've checked for a boost leak and can't find any but I only messed with one line and it seems fine.

[Gramentz]

Did you check the intercooler piping? Definitely make sure every connection is secure there. Otherwise, I'm guessing that the wastegate is dipping out on ya (I had one wastegate allow only 3 psi instead of 7psi until I put a boost controller in front of it) and your boost controller isn't reliable either.

[S13FASTBACKSR]

i think the reason your boost is dropping slowly from 10psi and 8psi when running your mbc is the same reason you are only boosting at 5psi without a boost controller..either your turbo and or wastegate is crappin out on you or you have a vaccuum leak or small boost leak...it is very possible that your dropping from 10psi and 8psi because its a garbage mbc...but the fact that your only boosting at 5psi without a boost controller somewhat sheds light on the mbc maybe not being garbage..even if it was only 7 dollars.

[240sxConvert]

Thank You. I will test for that. But if that was the problem...why would it not do it in 4th and 5th gear? I do not know much about turbos and am not saying you're wrong...I am just wondering.

[DrifterProdigy85]

Boost leaks is my guess too. T25 should hold 10psi pretty solid with all working stuff.