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I just started running EFI.. but I MIGHT have to make a fuel table just for racing... in open loop its
trying to drive the A/F to stoichiometric all the time
and in a max power condition you want somewhere in
the 12.5 range... so just for racing I might have to
with a fuel table... it can be way more consistent
if you stay in open loop and let the O2 do the work..
I'll tell you come spring time which way I go on
the loop thing




You definitely want to stay in closed loop with a target A/F ratio in the mid 12s, but you also want a base fuel table that doesn't require that closed loop does all the work. You want the base fuel table to be close to ideal. This is because the closed loop correction is always "behind the curve" because it only sees what has already happened. You don't want to run a race engine lean at any time.



do the aftermarket efi ecu's control fuel like the oem's do with short term and long term fuel trims??? If so then it can calculate fuel trims from engine load, map and/or maf, ect and tps position.
short term is real time fuel trim and long term is the correction table to correct the short term. The computer can actually figure out a long term fuel trim at a given engine load and tps position to compenste for "future table corrections" if that makes sense. I would assume a self learning efi system in closed loop would do the same??



I wondered this myself as all I have worked with is the Mopar OEM systems with the long and short term addaptive fuel trims. On the factory system I would consider the 02 sensor itself not a wide band as it really only has a small amount of control to fine tune the fuel mixture. But the 02 sensor does cause the short and long term fuel trims to drive into different cells and once in the proper full addaptive cell the 02 sensor will fine tune for the best fuel mixture as the 02 itself only can control a small amount of fuel trim within the addaptive fuel cell its in.
I wondered if the aftermarket systems many use work about the same as the OEM system that Mopar uses ?

I have to admit with the technology today the fuel injection will tune better then a carb can for sure and its great to have the fuel injection systems for the hot rodders to use. But I would not use it on a car like my 63 as I still love the old school carbs on my older muscle cars and hot rods.
I have to admit though that I saw a 64 Plymouth with a 426 Hemi and the crossram and it had fuel injection on it but you had to look hard to realize it had fuel injection as he hid the harness real good and the throttle bodies were about the same size as the carbs were and with the factory chrome air cleaner on it if you did not look hard you would have though it just had two carbs on it.

And for the OP question I would say if the carb is tuned good it most likely wont be any faster but even if you have the carb tuned perfect the EFI will be as good or better all the time since it can adjust and tune for weather and all without you having to lift a screw driver. If you get a good system and once it has learned all the fuel trims it will work good all the time as where you would have to stay on top of a carb to keep the right adjustment in different weather conditions all.
I still love using carbs but its tuff to beat technology. Ron