AFR Questions.....

So I just did a T3/T4 swap on the 88TC, also put my ported E6 on it while apart. Initially when the IHI was on it, I turned up base fuel pressure to 40psi, now with the T3/T4 at boost, 20psi, my AFR goes rich at like 10:1 even. I know more boost, needs more fuel, but does this seem overly rich? the IHI would run mid 10 AFR on the Autometer wideband, so what's the best way to adjust the AFR? Fuel pressure, or VAM? Thanks

Kuch,

Is your ECU chipped? Or are you running an aftermarket ECU? The 10.0 would be a little rich, but I have no idea how you would change a stock LA3. I'm running a PiMP ECU on my 88, with the fuel pressure at 43 psi. Under acceleration enrichment I keep my AFR at 11.5 through most of the full throttle range. For standard highway driving I cruise at around 14.5 AFR.

AFR of 10 or so under boost is Fords "safe" programming. Stock PCM does not use closed loop long term fuel trim corrections in open loop WOT or near WOT like newer PCMs do.

Does AFR stay at 10 at max boost and max RPM? Usually with some increased boost and airflow mods, the stock PCM begins to lean out AFR at higher than stock boost at high RPMs, as the PCM has no clue what the actual airflow really is. You can turn down fuel pressure a few psi to get a leaner AFR at lower boost / RPM, but be sure it doessnt go too lean at max boost and RPM.