07 Z06 long term fuel trim issues

[blindsquirrel]

Whatever could be causing it to not maintain fuel pressure. That could be a restricted inlet, restricted outlet (kink/bend in the supply line), a bad pump, bad wiring (voltage drop - could be on either the power or ground side), probably not a regulator since it's at its highest demand with the least amount of fuel consumed by the engine...

Just to be clear, nothing you do should be able to make fuel pressure drop more than 5 PSI. Ever. Under any condition.

[edcmat-l1]

If it's a 2007 pump you can probably guess it needs one. I also recommend using a hotwire kit whenever possible. They should be readily available for that car.

[92rsz]

You need a fuel pump. My z06 never drops below 58 psi unless it's at wot. Even then it only drops to 55-56 psi after 6k rpm. Only other issue it could be is a known problem of the connections in the fuse box not making good contact with the pins of the relay. But that usually results in a no start condition. +1 on the hotwire kit. Racetronix makes a good one for these cars

[Alvin]

OP here, just hooked up a fuel pressure gauge between fuel line from fire wall to fuel rail. At idle it sits around 56-57 PSI. A small blip of throttle will get it to drop a PSI at most for a moment.

If I really rev the motor it went to 42-38-36 PSI then picks back up, each of those numbers correlated to a throttle hit. If I sustain about 4k RMP it will drop but not far off idle PSI around 56-57PSI.

Working on posting a quick video

It just needs a pump. Hot wire kit is a nice accessory. Things do go bad.. This is pretty typical.

[edcmat-l1]

OP here, just hooked up a fuel pressure gauge between fuel line from fire wall to fuel rail. At idle it sits around 56-57 PSI. A small blip of throttle will get it to drop a PSI at most for a moment.

If I really rev the motor it went to 42-38-36 PSI then picks back up, each of those numbers correlated to a throttle hit. If I sustain about 4k RMP it will drop but not far off idle PSI around 56-57PSI.

Working on posting a quick video

If you were to go out and "make a pull" under WOT the pressure would drop much more dramatically.

[smokeshow]

Is the Map the only way a gen 4 senses barometric changes? I understand how the maf senses temp and humidity. The sensor on my 4th gen only has 3 wires and from my understanding is a linear voltage signal for just one sensor value. Everyone speaks of the computer knowing the ambient pressure as well as the manifold absolute, how so?

GM since way back when has used key on engine off map reading as baro check. Very simple strategy. No need for an additional sensor. At least up until the LSA/LS9 days.

BARO also updates at WOT on models that don't have a discrete BARO sensor.

Baro will update at key on engine off, WOT and part throttle. Each is calculated a little differently, of course.