I have a mild 350 in a 89 Firebird. The car came with a L03 305. I have
tried to tune the thing but am having a huge problem with a hesitation
anytime the throttle is barely off idle to about one third. The engine
leans way out (o2 at .06 volts) and it sometime backfires, If I floor
it, it ruins rich but it does pull and accelerate the car.

The settings I have right now are.

The BPW is stock * 1.1 134/160
All Pump Shots TPS is stock * 1.1
All Pump Shots MAP is stock * 1.1
Main Fuel Table all cells between 400rpm and 20kpa to 2000 rpm 50kpa is
at 100.
Vol Eff Adder 0 to 2000 rpm is at normal * 4

I know this is a really weird setup but I’m trying to richen up the
mixture at part throttle.

Any suggestions?

 

You should be able to make it pig rich by raising the BPW a bunch. Keep in mind that the BPW is not used while EGR is enabled and operating. A "BPW" Table is used during EGR operation.

100 in the VE table like you've described should make it pig rich also.

Have you ruled out mechanical problems? Fuel pressure, bad injectors, vacuum leaks, etc.

PS - there is a HAC of the 8746 at http://www.diy-efi.org/gmecm/ecm_info/1228746/

 

Thanks for the reply.

I think I can rule out injectors, vacuum, and fuel pressure. I put a gage on the fuel pressure, it was at 11 lbs. The injectors should be OK because it runs OK until it goes into closed loop. I checkd vacuum leaks and am almost certain there are none.

I've looked at the TPS voltage with a meter and it looks like it's OK. I haven't looked at MAP yet.