Quote Originally Posted by 1project2many View Post
My suburban is showing about 10-12% rich in closed loop. Initially I suspected across the board timing changes were needed for the 302 but those are not bringing O2 into line. I'm going to return to stock timing and see if the EGR is sticking open next.
That's about the same amount of change in cubic inches too? Have you done the VE tables? You still have the 98-00 Vortec PCM?

I've confirmed my issue once again as EGR. Turned it off yesterday and fuel trims were back to as close to 0 as possible all over but more importantly same bank to bank.

Going to try turning off the individual bank trims and see what happens, more curiosity. Seems like it would be a patch for a known EGR issue?

Also going to check MPG on this tank with EGR enable MPH raised to 25 MPH