Hey, I'm kinda new to the LT1 thing, and have some questions.

My car has an adjustable fuel pressure regulator on it. Where are you guys getting a fuel pressure reading. On an LS1, there is a port at the end of the fuel rail, but I didn't see anything on the LT1.

At WOT, an LS1 will use the O2 sensors to adjust the pulse width of the injectors, so fuel pressure plays a part, but ins't 100% critical. Does the LT1 do the same thing? What regulates the injectors at WOT?

(All this is for a 1992 LT1)

 

There is a schrader valve at the end of the fuel rail. Look again, pass side I believe.

 

Thanks, will do.

What controls the inj. PW at WOT?

 

Sorry, that I do not know.

 

Unlike the LS1 PCM, the LT1 PCM goes into "power enrichment" mode at WOT, and ignores the O2 sensors. It bases fueling on one of two things:

If the long term fuel corrections (BLM's) at high load were above 128 ("adding" fuel) the PCM uses the Cell 15 BLM's.

If the BLM's were cutting fuel in high load cells (BLM below 128) the PCM defaults to Cell 18 and locks the BLM's at 128.

In effect, you can not "tune" A/F ratio effectively with an AFPR in an LT1.

The Schrader valve (test connection) is on the supply line at the back of the passenger side fuel rail. The LT1 fuel system is also different than the LS1. The LS1 locates the FPR in the fuel filter, and returns fuel to the tank from the filter, which means the fuel rails are "dead ended". The LT1 uses a full recirculating loop, with full fuel flow supplied to the back of the passenger side rail, a cross-over at the front of the rails, and the return flow through the FPR at the back of the drivers side rail, to the tank.

Here is a picture of back of intake manifold, with the Schrader connection on the line to the passenger side rail. This setup happens to have a 90-deg -4AN fitting screwed on it, but yours will have a black plastic cap. The FPR vacuum compensation line has fallen off the AFPR in this picture.