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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

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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.

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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

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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.

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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??

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From what I was told it does it much like you said
and yes the self learn is in closed loop... it does
use the TPS, map and O2 .. right now I'm not using
the timing control

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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

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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.

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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??

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The factory stuff is only making changes to an overall multiplier in the short and long term trims. It's only "trimming" the fuel where it sees you drive it all the time in closed loop all the time - and changing the overall multiplier. At WOT it's going off the established fuel table - while using that same multiplier, but it can't change the table itself based on O2 sensor info. If it trimmed fuel at idle and cruise - it's going to pull fuel away at WOT too.

The modern standalone stuff looks at what your target AFRs are throughout the rpm range and load settings, and re-writes the tune to get it closer while it "learns". It learns at WOT as well as idle and cruise. Depending upon how much authority you let it have - it can change the fuel table slowly or quickly to get it pretty darn close. Of course, you can also pull up the logs and manually change the fuel tables to speed up the process.

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The factory stuff is only making changes to an overall multiplier in the short and long term trims. It's only "trimming" the fuel where it sees you drive it all the time in closed loop all the time - and changing the overall multiplier. At WOT it's going off the established fuel table - while using that same multiplier, but it can't change the table itself based on O2 sensor info. If it trimmed fuel at idle and cruise - it's going to pull fuel away at WOT too.

The modern standalone stuff looks at what your target AFRs are throughout the rpm range and load settings, and re-writes the tune to get it closer while it "learns". It learns at WOT as well as idle and cruise. Depending upon how much authority you let it have - it can change the fuel table slowly or quickly to get it pretty darn close. Of course, you can also pull up the logs and manually change the fuel tables to speed up the process.

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It still has seperate fuel tables for idle and cruise and WOT, while the O2's are narrow band(unless factory turbo car) it still tries for a predetermend fuel trim from fuel maps in the software. Now it can alter the fuel maps over time from learning how you drive, but OE's are based on fuel milage and emmisions production and don't set for best performance.

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My Dakota would slow down by 2 full tenths if I let the factory PCM "learn" while idling up the return road. It trimmed the multiplier - that also affected WOT operation. So every time I was in the staging lanes - I'd reset the PCM and let it start fresh. I finally just "forced" it to stay in open loop by unplugging the factory O2 sensors when I was at the track. It was very hard to go rounds with it slowing down every pass!

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Thanks... I dont know why I can never remember the loop
and I worked with injection for over 20 years.. but
I did the mechanical part.. nothing on the electrical part

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My Dakota would slow down by 2 full tenths if I let the factory PCM "learn" while idling up the return road. It trimmed the multiplier - that also affected WOT operation. So every time I was in the staging lanes - I'd reset the PCM and let it start fresh. I finally just "forced" it to stay in open loop by unplugging the factory O2 sensors when I was at the track. It was very hard to go rounds with it slowing down every pass!

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You really can't use OEM ECUs for racing unless you can get into the program and change the target A/F ratios and the strategy whose objective was related to the control of emissions, not WOT operation. GM guys can do this easily, but not so easy with Mopar ECUs. I have done it but it wasn't easy nor legal for street operation. If you are in a state that does not have strict emission laws the way to go is with an aftermarket ECU that you can tune.

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Thanks... I dont know why I can never remember the loop
and I worked with injection for over 20 years.. but
I did the mechanical part.. nothing on the electrical part

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"closed loop" is controls terminology, it means that the feedback control loop is being used. In other words the controller is looking at the output of the system and feeding that information back and adjusting the input. In this case injector duty cycle is the input and O2 is the output. If you are "open loop" you are working purely off a control map based on the inputs of all the other sensors to determine duty cycle and not using the feedback of the O2 to adjust.

-Michael

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For some reason I use to think of it as open loop =
open minded... looking at everything... I just have
to get that way of remembering it out of my head