Open loop mode switchover point?

[destrux]

Does anyone know what exact condition triggers the 1JZ ECU to switch to open loop mode? I'm looking for something like the exact TPS percentage where it switches or something. I'm assuming it uses the TPS signal to trigger it, maybe it uses a certain MAP reading, or a calculated load value...

I'd like to set my AFC up so that it switches to the high throttle map at the same time the ECU goes to open loop mode.

 

[GrimJack]

Unfortunately, Toyota seems to have a habit of calculating this using 85% sensible input values, as you've surmised, and 15% made from random amounts of voodoo and witchcraft, with an occasional dash of divine intervention.

 

[destrux]

So, guesstimating 74% low and 75% high for throttle points is probably the closest I'm going to get.

I just want to prevent the AFC from switching maps while in closed loop (as best I can), for the best fuel economy and driveability.

If it the AFC is changing the correction values too much in closed loop it's going to cause the ECU to be moving the LTFT all over the place, and since the closed loop LTFT adjustments also affect open loop a/f mixture I don't want the ECU to be leaning out my WOT tuning on it's own.

It seems the easiest way to prevent this is to just use the same correction value on the entire low and high maps in the AFC... which is what I'm doing at the moment. I have -10 across the board on both maps. The problem with this is that it makes tuning the high map a PITA. I have to let the LTFT stabilize for a few hours of normal driving, then check WOT a/f, then adjust all the values and let it readjust for a while, then recheck.... repeat... PITA.

I guess I could also drive the car around and let it adjust to a certain value on the low map (say, -10... which is working fine daily driving it right now) and then adjust the high map so that it's always leaner than the low map (while also targeting a 11.5:1 AFR). The car should almost always be in open loop over 75% throttle, and if for some odd reason it isn't, it will see leaner values than the low map and temporarily richen the mixture, not lean it out.


Maybe I worry about this shit too much. I drink alot of mountain dew.

 

[mk3tattoos]

I was always under the impression that trying to use the low settings was pointless.

I have no problems here with just using the high settings.

 

[destrux]

How much correction do you have on your high map with the low at zero?