Adj fuel regulator

[red4thgen]

I got a full bolt on 93 Camaro and it seems to be running a little fat. Just wondering if anyone had any luck leaning out with a adj fuel regulator. I could fix it in the tune but it's just such a hassle for the mail order tunes

[Injuneer]

When you reduce the pressure, there is a brief reduction of fuel flow = leaner. Then the O2 sensors read "lean" and the ECM uses the long term fuel trims the richen it back up. At WOT (PE mode) the ECM ignores the O2 sensors, but if the LTFT's were adding fuel before it went into PE mode, it will continue to use those "richen" LTFT's. Net change = 0.

Under what conditions do you feel it's running rich - under part load in closed loop? ....in PE mode at WOT? .....both of the above?

Has it always run rich with this tune, or is this a recent development? The are several problems that will cause it to run rich.

[red4thgen]

At idle the exhaust smells rich and at cruising speed.it even leaves my bumper black. I got the tune front solomon not sure if u herd of him but other than that it runs strong.I should probably get a wideband to really see whats happening.

[red4thgen]

Do you know if I data log it will it show air fuel ratio?

[Injuneer]

There is no accurate indication of the actual A/F ratio. The ECM is hard coded to produce 14.7:1 in closed loop. If the O2 sensors show it is deviating from that value, the PCM adjusts the LTFT's to get it back. But there are external things that can throw the O2 sensor readings off - innacurate sensors, misfires, exhaust leaks before the O2 sensors, and wiring problems.

At WOT (PE mode) the PCM richens the mixture for increased power and torque. But then the O2 sensors are totally inaccurate, since they are only intended to be accurate at 14.7:1 +/- 0.1 A/F ratio units. The ECM with a stock tune will generally produce a target A/F ratio of 11.7:1 at WOT, although most tuners lean is out a bit to 12.8 - 13.2:1 for better power. A scan will tell you the target A/F ratio at WOT, but that's just the value the ECM is trying to achieve, not feedback as to the actual A/F ratio.

Do you have a cat? Removing it allows unburned hydrocarbons to exit the tailpipe, and they will make it smell rich.

[red4thgen]

Ya no cats no misfire or exhaust leaks. Its got new delco o2 sensors 1 wire. Also thought about switching to heated o2 sensors. I think a data log will probably be the next thing to do