R33 boost spike issue

[Custard]

R33 boost spike issue

Hi all, I need to find a solution to fix a boost spike issue that my car has. It's a 1997 manual GTST, only mods are YJ coils, return flow FMIC, MBC and 3 inch turbo back exhaust.

Since I installed my front mount and dialled my boost up to 10/11 PSI I have noticed that when I punch it from 3.5 grand upwards the boost will spike to 12 or 13 PSI for a moment and then taper back to my set pressure. Just last night I installed a JJR bellmouth 3 inch dump pipe and now when I punch it, it will spike to 15 PSI! Would prefer not to launch my exhaust wheel out my exhaust, so I need to get this under control. Do I need an electronic boost controller or what?

 

[Custard]

I have a cheap 'Drift' brand MBC - would be I correct in believing that this is a bleed type MBC? Would I benefit from changing to a ball type MBC such as this? http://www.ebay.com.au/itm/Turbotech-manual-turbo-boost-controller-THE-ORIGINAL-and-still-the-BEST-/321155544509?hash=item4ac65cb5bd:m:mJ5Yk12EnMVqXBuR8UxKxhQ

[jhjones]

connect the wastegate actuator hose directly to the intercooler pipe and see what happens

Edited November 18, 2016 by jhjones

[djvoodoo]

Why don't you just turn the boost down via the MBC??

[Custard]

1 hour ago, jhjones said:

connect the wastegate actuator hose directly to the intercooler pipe and see what happens

Okay, I did this. I saw 5 PSI when easing into boost and around 6-7 when stomping it from higher revs. I had a thought: perhaps with the addition of my front mount intercooler, the extra volume that has to be pressurised before results in the opening of the wastegate being delayed? If this was the case, would relocating the barb from the cold side to the hot side fix this?

13 minutes ago, djvoodoo said:

Why don't you just turn the boost down via the MBC??

Probably would have achieved the same result what as post above suggested, but it's done now.

[Sklyn]

Just to be sure, the stock solenoid has been disconnected and the other hose blocked properly right? Getting 5 and 7 suggests the stock solenoid is still in use. Are your psi readings from an aftermarket gauge? Stock one is not psi.

[Custard]

35 minutes ago, Sklyn said:

Just to be sure, the stock solenoid has been disconnected and the other hose blocked properly right? Getting 5 and 7 suggests the stock solenoid is still in use. Are your psi readings from an aftermarket gauge? Stock one is not psi.

Yes, actuator is connected straight to the nipple on the cold side of the intercooler piping, no stock solenoid. Readings are taken from an aftermarket boost gauge in PSI. The higher boost level that I'm getting isn't dependant on my RPM but rather how hard and fast the boost is coming on. 

Edited November 18, 2016 by Custard

[Custard]

Because I'm getting boost spiking on just wastegate pressure, would this suggest my wastegate actuator is no good? 

Edited November 21, 2016 by Custard

[Sklyn]

Very well could be that. When i started to get 7 on that set up i replaced it and went back to normal. I then put in an r32 one for an easy 10 psi with no need of defectable boost control.