1jz-gte boost, ignition, or fuel cut?

[1990MA70]

Hey everyone. Had some quick questions. Just recently I turned up the boost in my 1jz-gte swap. When I first started turning up the boost everything was perfect. Then a week or two later I started getting some sort of cut, only in higher gears when im on the throttle for longer periods of time (most common 4th gear WOT)I get a quick cut like a limiter. Only thing is 1st, 2nd, and 3rd gear are no problem, never cuts

So my question is, Am I hitting a fuel, ignition cut? Or is it the injectors/pump being too small? Maybe bad coil packs?

Car specs:
1jz-gte swap
Holset hx35 single turbo
stock injectors
stock ecu
stock fuel pump
Shell V-Power 91 OCT.
driftmotion wastegate (7psi spring) bumped up to 12-13psi
AFR's around 10~11 WOT

My thoughts are:
If it was coil packs id be breaking up in all gears at WOT?
If it was fuel (injectors, pump) id be leaning out?
And I know people running 1jz's over 18psi on v power so i don't think its the fuel im using?
My last idea is that maybe my boost is creeping above the 14psi limit? (But why is it happening more often all the sudden?) :1zhelp:

Anyone have any other ideas?

Oh and just for shits, what is it exactly when the stock ecu see's over 14.7psi of boost and cuts_______?

Thanks!

Sorry for the onslaught of questions

 

[rhs]

I would guess boost cut. Are you sure your wastegate is working?

 

[suprahero]

I wouldn't think you'd be blowing the spark out at your boost levels. You could try closing the gap on them a little bit to see if that helps. If it doesn't, It's more than likely boost cut.
I used to run my plugs gapped at 18thousanths, but that was with 20 psi.

 

[hvyman]

Boost cut is at 14 psi.

 

[Radial]

+1 for boost cut IMO.

4'th gear is where you usually experience some minor over-boost, even with a stock engine.
And a minor over-boost at 13psi sends you right into boost cut.

1-2 and 3 gear does not load the 1J enough to generate an over-boost.


Tip:
Use the highest octane rating available at you gas station. 91 seems a bit low.

 

[1990MA70]

Thanks everyone, sorry I've been away for a while. Had a ton of snow a while back and the car got put into hibernation. I backed off the boost controller a bit and hopefully the snow will melt enough in the next week to test if that works.

Unfortunately 91 octane is the best I can get in my town unless I drive into the city, meth injection will be a priority once I start making more power with new fuel and ecu upgrades

 

[3p141592654]

Check for codes. That should help narrow down what is happening.

 

[sfgsdfg999]

Do you have an FMIC or are you running the stock side mount?

 

[1990MA70]

Sorry for the spotty late replies, finding it hard to get online lately and it snowed almost a couple of feet last week... I'm running a Blitz from mount. Ecu shows no codes other than speed sensor but i don't have it wired in... Though i dont think its speed sensor. I've had that code since i swapped the car and its never bothered me or made any changes in how the car drives. But it doesn't look like ill be able to find out what's really going on until spring now unfortunately...

 

[sfgsdfg999]

At 1 bar the ecu shuts off the injectors for boost cut, which you would feel, without some sort of piggyback or FCD you will hit it - I would also advise in getting a better wastegate, cheap ones will leak. Your injectors are maxing out duty cycle at 300hp, upgrade the fuel pump, bypass the dampener and get 550cc (skip the 440's).