I'm really bummed. My engine would not tune and had a terrible off-idle hesitation. I discovered fluctuating fuel pressure and air getting into the fuel lines with the in-line pump. Since the tank had to be replaced anyway for another reason, I went to a bone stock in-tank fuel pump setup (copying a 1991 Blazer). This is for a GM TBI 7747. Fired it up today and started tuning. First of all, the hesitation is not gone. But, maybe it just needs a tune. Thing is, the first time out I came back to adjust the VE and I have values as high as 112. And this is with the BPW already bumped up from 135 to 150. The BIN I'm starting with is ARJT, which I adjusted so that the VE2 table is zeroed out - just to make the tuning easier.

One thing is that the 135 BPW seems to come from a nominal fuel pressure of 12 PSI. My fuel pressure is steady at 9-10 PSI. Just working the math, this would seem to want to push the BPW up to about 180, all else equal. The only major mod to my engine is headers, but that might push the efficiency up a little. I don't mind trying the 180, but it makes me wonder how this ever worked in the factory. The VE table doesn't seem to have enough range to soak up any fuel pressure variation at all. I've read that any VE over 100 will just limit to 100, even if it's the combination of VE1 and VE2.