Need help with A/F error%

[01SDime]

I'm trying to get my Actual A/F ratio to match my commanded (11.8) while in boost, by logging the A/F ratio error % and then adjusting the VE table based on the % of error. In my second log this appears to have worked great up to 140 kPa, but after that it didn't seem to do anything at all. Especially in some areas, such as around 160-165kPa, I took out 8-10% from the VE table (used copy, paste special->multiply by %), and the AFR error% still remained the same at around -8. Why didn't it change at all? I would of thought by taking that much out I should of seen at least some improvement. Both runs were done in 3rd gear, 1:1 ratio (4l60e). In the second log (AFRErrorTuning2.hpl), my 3rd gear pull was the very first run you see where the inj duty cycle climbs way up over 100% (at the 10400 - 10500 mark).

Some information about the truck:
'01 S-10 with 4.3L V6. Mach Performance kit: Procharger P-1sc at 10psi with 3-core intercooler.
Procharger FMU.
Forged pistons (8.7:1 cr), h-beam rods, bored .030 over, bowls blended on heads, 3-angle cut valves.

Running 2-Bar OS with GM 2bar map sensor.

Attached are my two logs, and two corresponding files that go with those logs, and my config file for VCM scanner.

Step 3-2BarVETuningBoostTuning3.hpt was the file used while logging AFRErrorTuning1.hpl

and

Step 3-2BarVETuningBoostTuning4.hpt was the file used after adjusting VE table based on A/Ferror%, and was programmed into the truck during the log of AFRErrorTuning2.hpl.

Any help that can be given would be most appreciated. I'm at a point where I'm stumped and not really sure where to go next with this tuning.

[blownbluez06]

You pretty much answered your own question. You're running out of fuel on the injector and possibly on the supply side. Watch or log your fuel pressure. You will have to get a manual gauge and watcht it or add a sensor to log fuel pressure.

[TURBO 6.0]

130+ on the injector duty cycle! What size are your injectors? Either way it's time to upgrade.

[01SDime]

You pretty much answered your own question. You're running out of fuel on the injector and possibly on the supply side. Watch or log your fuel pressure. You will have to get a manual gauge and watcht it or add a sensor to log fuel pressure.

If I was running out of fuel pressure I thought I would run leaner in higher boost instead of richer? I apologize, I don't understand could you explain further please? I have an electric fuel pressure gauge (Autometer), but its always been pretty crappy and right now I'm having trouble with it reading about 5-6 psi under what it actually is (for instance, idle says 53 psi but with a mechanical gauge I measured 58psi which is what its supposed to be). Next time I make another run though I'm definitely going to log Fuel Pressure on the scanner.

130+ on the injector duty cycle! What size are your injectors? Either way it's time to upgrade.

Fuel Management Unit, stock injectors. Those duty cycles have to be that high with an FMU otherwise I have a serious problem of absolute 0 fuel going into the engine when I hit boost. You'd probably see the A/F ratio jump up in the 20's if they didn't go that high lol. Ever seen the "spider" injector setup on the 4.3L's? There is no way to upgrade those to bigger injectors.

[Frost]

.. Those duty cycles have to be that high with an FMU otherwise I have a serious problem of absolute 0 fuel going into the engine when I hit boost. You'd probably see the A/F ratio jump up in the 20's if they didn't go that high lol. Ever seen the "spider" injector setup on the 4.3L's? There is no way to upgrade those to bigger injectors.

I have no idea what you are trying to say, but at 100%, the injectors are static. That means open all the time and no more is going to go through them. The 130% is some calc'd number. If they reach 100% though, you are out of fuel.

[01SDime]

Oh ok I understand. I thought it just read that high because of the FMU pushing the stock injectors to spray more fuel then they are supposed to actually do standard.

[murphinator]

how old is the fuel pump ? a friend of mine just dropped IDC's from 80's to 60's with a new stock pump.

do you have any type of fuel pump rewire to ensure plenty of voltage to the pump ?

[01SDime]

The stock pump would be 8 years old, but the truck only has 19,000 miles on it. Mach Performance's kit also came with a secondary pump and filter as well, which would be about 4 years old now. That pump I know is working fine as I just tested it recently. I don't think there is anything wrong with my fuel pumps, I think its just the Fuel Management Unit which is making my tuning process more difficult. Even if I went with a bigger fuel pump, as it is right now I'm stuck with the stock injectors and the FMU is still going to want to force those injectors to work harder than they can. Wouldn't it just continue to see IDC's over 100%?

I'm still a bit confused by what is meant by when an injector goes static. With it going 100% and static, is the Fuel Management Unit just forcing the injector to dump a ton of fuel into the engine and make it overly rich above 140kpa?

[qwik48r]

a piggy back I would think would really make tuning difficult...

going static means the injector is ON.. not ON off ON off like a normal pulse... meaning the only way for the injector to try and keep up with demanded AFR givin its VE/MAF curve is to stay WIDE open... they are completely saturated at this point and the only fuel control you have is with the actuall line pressure point at saturation point...

the only thing I can see is this FMU pushes the injectors to run saturated to give enough fuel... sounds like a cheap fix to me.

[01SDime]

Ok I see. Thank you guys very much for your help. Sounds like I need to bite the bullet and buy the marine intake if I want to tune this thing the right way.