1jzgte TT Boost creepin

[splatman1]

Hey guys

Boost creep life

Got my jzx91 with a 1jzgte(stock twins) r154 in it.
Has a big front mount and a full aftermarket 3inch exhaust going through.
Im assuming thats the reason of the increased boost.

It hits the 7-8 pound very quickly on decent revs and creeps up on WOT all the way up to boost creep at 1bar.
Can hit boost cut at 5-6k when flooring it(especially on ramps ). Got a EBC i want to put in but untill boost creep is under control im under the impression its pointless.

Lots of googling leads people to saying a 2" restrictor ring in the exhaust is a good way to increase the back pressure and bring that boost down.
Other people say its a bad idea.

Any suggestions/opinions on ways to go about this?

Cheers

[Looonie]

I was only aware of the exhaust causing overboost issues in JZA80 and JZS147/161.

Never heard of it on a TT 1JZ.

Do you have stock turbo y-pipe? If so that should be creating well enough restriction to stop creep.

I would be looking for other causes... split hose to wastegate, washers under wastegate mounting, lengthened wastegate rod or just flat out faulty wastegate.

Presuming you're still taking the wastegate reference feed from the turbine housings and haven't changed anything there?

[splatman1]

Seems to be stock downpipe from visual inspection through top sensor hole and from underish car when not jacked. Looks brown from that 20y/o rust.
It seems other people have these boost creep issues after exhaust changes. Or maybe its just coincidence. It slowly creeps up from 7 but can hit 14.7 before 6k rpm.
If it could be other parts then a good check will turn into seal rebuild on the turbos. So could be a good thing to do all together in the near future.
Thanks for some tips at things to look for though

[Brett7777]

Boost cut on the 1jz is common as. Lotta guys i talk to at the drags get it, and thru talkn to peeps on the net too.
Mine got it after decat and 3.5" catback and pod. Went to 15psi on my boost gauge. Since ecu reset it has currently settled at about 12.5psi max but Im monitoring it.
the cut happens if you get to 14.7psi for 3 secs or more. you can use a boost cut controller like the hks fuel cut defencer to bypass it. (the boost cut induces a fuel cut to slow you down, the BCC tricks the ecu into bypassing that)

[Brett7777]

and restrictor ring will just slow you down, and who wants to go slower?

[Brett7777]

Im gettn this put in to deal with the boost cut

[BlakeNZ]

Chuck an air compressor nozzle up the pipes that lead to the actuators, just to make sure they are opening under boost. For instance if one wasn't working properly, and the other one was, then you may see 15 psi boost, but in reality you have one turbo doing 11-12 psi, and the other providing much more.
If all looks good, set the boost cut controller to just above where it spikes to on a cold night, then drive it like you stole it.
sometimes it is good to check your air fuel ratios at Wide open throttle(WOT), just to make sure your (possibly)25 year old fuel pump is not tired/lazy.
Assuming the actuators and waste gates are working well, the higher the boost it does naturally(i.e. without a boost bleed or boost controller) the better you have it breathing. Those stock turbos LOVE to breath. IN and OUT.
generally the 1JZs run rich on stock ECUs at WOT, which helps to keep the ceramics cool.
My car runs up to 21.5 psi even without turning the boost controller on.(this is with extensive intake and exhaust mods, and on E85 fuel.
We found the limits of the stock soarer fuel system at 245 rear kW, at 5000 rpm, on pump 98.

[Brett7777]

Blake you're a friend of Shyam's? I live down the hill from him and met him a while ago.
I saw some pics of your soarer that he posted on FB it really gives me some inspiration fro my jzx90 drags car.
I need some advice though bro, I was hoping to be able to ask you some things at some point.

[splatman1]

Brett, this post is ancient mate, ill message u on the facebook haha. Also livin the soarer life to blake. 1jzgte vvti. Unfortunately the chaser guys are really the only knowledgeable guys around on the vvti 1jz that im aware of.