I did the tbi mods listed (removed ridges&gold ring) and installed an injector spacer and now it will run better at 3/4 throttle than at full throttle. It seems to lay down as the rpms rise under full throttle but then you can back off a little and it accels faster.

I'm wondering if its going lean due to more airflow.

Its a 91 gmc swb truck 350 auto.
No cats, true duals, 360degree open aircleaner, underdrive pulley, tbi spacer, injector spacer, stage2 chip from tbichips.com.

I'm ordering an adjustable regulator from Jet to see if more fuel pressure will help. If not I will take off the injector spacer and see what happens. Problem didn't start until spacer and tbi mods were done.

Any ideas?

Thanks

 

you really need to get a data logger to be sure of what the computer is doing and what your fueling looks like. winALDL is usually the preffered program with the tbi users. Its free and you can get it here. This is also a must if your going to be tinkering with the fuel pressure.

P.S. welcome to the boards

 

it may feel one way or another but I guarantee youll never really know what its doing unless you get some real data on what the engine is doing and not from your SOTP dyno. Either way, you dont really know if its laying down, and you dont know if its lean. Assumptions in this hobby can really end up screwing you over

at a minimum look at what your oxygen sensor is outputting at WOT... youll see a drop lean enough to hurt performance that you can feel with one. An accelerometer like a G tech is also helpful here too since you believe it pulls harder at part throttle just set it on the g function and hold a given part throttle setting as measured at the tps (for true accuracy) in a given gear and repeat the test at WOT.

like i said, you cant really tell with your butt, (unless its extreme)

 

You might save yourself some money and just make your stock fuel pressure regulator adjustable. Check the tech articles. But if you are really looking to buy a new one I would go with the Vafpr one from GM.

 

I've already ordered an afpr from JET. After searching this site it does look like a vafpr would have been a better choice.
I'm going to get a fuel pressure gauge to see if pressure is dropping at WOT.

Also looks like I need a laptop and make a cable to see what is really happening.

Thanks for the help even though I have a truck. I know there is a lot of experienced people on this board.