Hello,

I had a problem with the injectors on my Fiero 85 V6 ECU 1226869 and swapped the original 5235210 (14.65LBS/HR) for ones from a 91 Firebird 17084888 (15.4LBS/HR), 5% more flow.
The engine runs well, but smells a bit like gasoline.

I noticed that the BLM is always at 120 (=minimum), so the ECU constantly wants to reduce gasoline by about 6%.

Which value should I adjust with TunerPro to get the BLM to regulate again?

1.) Minimum BLM from 120 to 115?
2.) Reduce Base Pule Constant from 224 by 5%?
Table "Base Puls Constant V. EGR Duty Cycle" also reduced by 5%?

Or another value?



Greeting.

I am not a tuner. I have learned over many years of racing to always change one thing at a time and view the results before making another change. My observations:
1) You increased injector flow by 5% without making changes.
2) BLM is stuck at minimum so you cannot be sure if it wants to actually remove MORE fuel

To me the logical choice would be to reduce base pulse constant by 5% FIRST (assuming values were all in line with the original injectors) then drive for a bit and see where the other values settle. Keep in mind BLM equates to long term fuel trim and is learned over time. Integrator equates to short term fuel trim and is the "active" adjustment. As I understand it "128" is a typical integrator value and yours is way below that so it too is actively looking to reduce fuel flow.

It would seem you need to reduce the base flow on the bigger injector for normal driving and get it more "centered" in the range of automatic adjustments the system can make.

Is the BLM and INT staying static at 120?

BLM is stable at 120, INT is moving.

[This message has been edited by jtontch (edited 05-19-2024).]

Check for properly operating O2 sensor? I'm assuming you are in closed loop.

I would also adjust the base pulse constant.
I made a similar adjustment when I added the Allante intake to my 4.9. Both engines use 19# injectors, and are rated at 200 HP, but the Allante is a 4.5, vs the 4.9.
I think I increased it by 10%. At a steady cruise, my BLM hovered around 128, afterward.

I have opened up the MIN/MAX BLM window on a couple of cars, but it was strictly as a "band-aid", for someone who insisted on running too small injectors in a 3.4. The ECM was constantly trying to add gas, and was maxed out. At least it ran better when it switched to closed loop.