fuel cutout at full boost

[90gst]

Hello, I have a 90 gst with blowthru and maft. the turbo is a big16g, and 2g exhaust mani...On my car even before the turbo, the fuel would cut out at full boost... Before it was set at 12psi and would cut out when it peaked at 12...now Im running it at 15psi fuel pump rewired and it still cuts out around12-14psi...I know its at full boost because my turbo is ported and clipped and will boost to 12pst at 2500rpm and it will cut out...if I cruise cruise at 4k rpm and hit the gas, the car boosts imediately and fuel cuts out...It doesnt matter what I'm cruising at, as soon as the turbo screams, "literally", fuel cuts out, I was wondering if it could be a weak FPR. or maybe a bad crank sensor? I dont know if these cars come with a tps and needs to be adjusted? any ideas or help will help me alot. I'm good with cars but I cant figure this one out. Maft is set correctly

 

[JessesTalon]

if you have stock injectors still your prolly maxing them out the but

 

[JessesTalon]

yes they have a TPS.

Also try doing a few basic things like Leakdown test and if you have access get a identical ECU and run it instead of yours and see if its a ECU problem possibly.


But my money is still on stock injectors running a b16g

 

[Goodguy162000]

So you have a ported 'n' clipped B16G and you're spooling at 2500k?? WTF Hmm. Yeah, think general maintenance dawg. You're working with a 16 year old car. How's your fuel filter working? When was the last time you cleaned your fuel injectors or ran something to do the job for ya? Start w/ the simple and go from there.

 

[steve]

Does the car start soft misfiring or does it feel like you ran into a wall.

Fuel Cut is airflow based. As soon as the measured airflow exceeds the trigger value the ECU turns off the fuel and it feels like you hit a wall. Datalogging will show this as your injector pulse width (IPW) going to 0 while your throttle is still open (to differentate from decel fuel cut). Boost leaks are the most common cause but once you start really upgrading the car it's just something you have to work around or remove with a EPROM ECU and custom chip or DSMlink.

Running out of injector just causes the car to run leaner and leaner until you melt something. It shows up on the logger as injector duty cycle (IDC) >100% but it doesn't cause fuel cut. You can easily max out the stock 450s with a B16G by running over 12 psi.

Steve

 

[90gst]

I'm gonna do the fuel filter. car had a leakdown test and a compression test. Pressure dropped 1psi in 50sec...Is that good or bad? Compression checkd in at 143-145-143-147. I've put injector cleaner twice. Do you think if I get the 550 injectors and tune the maft to them, it'll be fine while I get the datalogger and s-afc?

 

[90gst]

also would there be a way to lower boost like to 7-8psi?

 

[90gst]

??? anyone know how to lower boost? I got a mbc and I removed the spring and the ball from it but it still boosts around 12psi