Long story short, I got my engine back from the shop. The fuel rail had one of the tabs broken off so they swapped it with a LS fuel rail and FPR.

The fuel rail is not correct, as the injector harness is mashed against the manifold.

My question is this: Do the FPR's on the LS vs GSR differ in pressure?



Here is my sequence of events:
P0420 - Bad Cat (Had this for years)
Rebuild motor at Redzone
P0420 & P0131 - Replaced Cat, SO2 & PO2 Sensor
P0171 - Replaced fuel pump, no vacuum or exhaust leaks found, checked and rechecked valves. This code will not go away.

All I can think of is that the LS FPR is running my car lean. I never got that code before the rebuild. I don't think one or all of the injectors are bad either, but that is a remote possibility.

 

did Redzone break the tab? either way since they put your motor together you should ask them about your situation

 

All FI B's and D's use a regulator that lowers fuel pressure by 9-10 psi. You can borrow a fuel pressure gauge from a parts store and check the pressure with and without the regulator vacuum hose attached to see how the system is performing. However, a bad FPR could only make the ratio too lean at the top end. You might want to check the TPS. Also, if you can find out at what point the code pops up- high/low RPM, WOT throttle, etc- that might shed some light on what's going on.

 

It only throws the code under load and it did come on right after a hard pull onto the freeway, which scared the crap out of me. If I drive it around slow, it sets all the OBD2 monitors in 2 trips. As soon as I take it to the smog dyno, or get on it, it throws the code.

Redline can't find my original rail or FPR, but they have offered to pay me or find me one.

So, if they are all functionally the same FPRs, then it is either bad and letting too much fuel past, or it's something else. TPS voltage is good.

 

Definately check the fuel pressure. If you put down a deposit at Autozone, they'll loan you a fuel pressure gauge. Check it real quick in the parking lot and get your money back before you leave.

 

I just swapped out the FPR for a GSR one, I think the only difference is going to be the angle of the vacuum nipple. Next step will be to check the fuel pressure with a gauge.
Thanks for the help!