Jump to content
SAU Community

Recommended Posts

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?

 

Link to comment
https://www.sau.com.au/forums/topic/467794-r33-boost-spike-issue/
Share on other sites

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

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. :P

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.

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 by Custard

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • The German place in Cabramatta was rock solid, fresh pretzel cooked to order back then. Then it went all quiet, after all the poker machines were removed, then I believe it closed for good. I did drive past the other week and noticed outdoor lighting a big screen, but no idea what is there now.  
    • Yeah I suspect even if you hold airmass per cycle/cylinder constant if you get too far away from stock you're still going to have problems running the factory tune within the bounds of the factory load scale. Cams, different displacement/rod ratio, etc. I'm just lucky that the GTIII-SS with wastegate boost + CA compliance cats is pretty much equivalent to stock turbos. When I have actual space I can finally get it tuned and modify the fuel system for flex fuel to 100% handle any detonation concerns when cranking the boost to whatever those dinky turbos can put out.
    • I would say no, why, because my daughter, who also lives in Goulburn, hasn't recommended us going there Pity, as we miss all the German joints around in Sydney, actually, the restaurants are the only thing I really miss about Sydney, and a special mention to Ishibanboshi at Bondi Junction, their Kara-age Don is heart cloggingly deliciousness (always added a special boiled egg...or 2) 😋 
    • Does that German restaurant still exist in the old place out the NW end of Goulburn? When I say "out the NW end of"...I am really being vague. It was 1997 when I was last there, and the only point of reference I can recall is that it was on the opposite side of the main drag from the big merino. And when I say "opposite side of the main drag", I don't mean "on the main drag". It was either a couple of streets back from there, or might have even been out in the sticks a bit further. Was an old farm building or mill or somesuch. And when I say "the big merino" I might actually be thinking of a completely different part of town, because I just looked on maps and the big bugger is not where I remembered him to be! The food was good, consisting largely of various German mystery-meat sausage/loaf things and kartofflen.
    • So while the second sentence is completely correct and the whole point of the conversation, the first sentence bears consideration. If this bloke is just hoping to throw big turbos on and drive it around, because there are no helpful facilities at all in his tropical paradise** then he likely has zero chance of even knowing what the TP is on the last column in the stock maps, let alone know whether the ECU is operating anywhere near it or past it. So the point is very very moot. And, per what I said before, at stock boost on those turbos, you may well be off the end of the map. **I'm just back from Vanuatu, so I know exactly what small Pacific nations can be like wrt paradise without requisite facilities. But it's not even that simple. I put a high flow on my car and had to drive it around without a proper tune because of the lack of opportunity*** to put the bigger AFM and injectors into it to allow it to be tuned. I had to turn the boost down to less than I had before, and back off the boost controller's ramp, because it was exploring parts of the map that it didn't drive in before, and really couldn't access for tuning on the dyno either, and so was pinging. It was still well within the last column, because when I first**** set up the Nistune on the Neo I rescaled all axes of the maps to give some more space to explore. ***Family dyno was broken ****This was 13 years ago, and the TIM thing wasn't a thing then and so TP would definitely grow when pushing past the stock tune's limits.
×
×
  • Create New...