North American Turbocoupe Organization

AFR Questions.....
Kuch Offline
Senior Member
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
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4, ported E6, 255LPH, Kirban, Stinger Exhaust, MGW shifter, K&N, Gillis valve, BP1.5, PIMPx, Koni's
1964 Ford Galaxie 500XL, 390 6V, Big Solid cam, Headers,3.89's, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 312 4bbl intake, headers, 3 Speed, slow and low

Dan S Offline

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.
Dan S
Custom 88 TC, Mandarin Copper Pearl Metallic
1972 Ford F-100 SWB Styleside
2015 BMW 435i Hardtop Convertible 
2022 Escape Titanium Elite

Jeff K Offline
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.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized

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