search came up short

im trying to figure out what exactly or where exactly an ecu goes from closed loop to open loop. word of mouth at preludeonline.com(i own a bastard prelude) is that the crossover is at 33% throttle.

reason im asking is my engine is being built currently, i have just purchased an lm-1 and i need to set the throttle positions on my vafc so i do not tune anything in closed loop as i do not want to make my STFT or LTFT go haywire on me.

and yeah.....i know...get a hondata

 

It also depends on when your car warms up enough for the galvonic battery (O2 sensor) to come into effect thats when closed loop comes into effect. Until closed loop your ECU runs everything off of its preset perameters and other inputs, like TPS, MAP, MAF and so on. Hope this helps

 

yeah i know it runs open loop untill the o2 sensor heats up but thanks anyway.

i guess maybe i should be somewhat more explanative.


after the the car warms up and the ecu is switching from closed loop to open loop based on throttle percentage what is the actual crossover point. like i mentioned previously people have said that at 33% throttle is the crossover. now that i think about it im thinking its sounds very suspicious that closed loop/open loop transition would be soley dependant on throttle percentage alone. i would think that rpm should have something to do with it since one of the reasons for the whole open loop closed loop function is that at a certain point the o2 sensor isnt fast enough to provide acurate data.

screw it, if the fuel trims get messed up and i blow the motor again i'll just light the ****** on fire and get a new car.

 

i have noticed with my wideband, that tapping tha gas (possibly as low as 20%) will pull it out of the 02 and onto a map.

also, my obd0 car does some really wierd stuff when its using the nonexistent 02 sensor, and thats how i can determine when it goes from open to closed

 

you mean open loop to close loop
the actual <U>cross over point is when the car reaches normal operating tempature and the o2 or hO2s.</U> Untill the demands are met it runs soley off the ecu instead of the of the input and output sensors. The throttle % has no demands for the ecu to run closed loop. if it continues to run open loop and completes its drive cylce (ObdII) then it goes to limp mode (don't want to go to that too much details).

 

no no no your not seeing what im saying.

yes when you first start the car up its in open loop untill it warms up and then it switches to closed loop. well after that closed loop only works untill a certain rpm or throttle percentage then it switchs back into open loop, ex. idle is closed loop and WOT is open loop. what im trying to figure out is the throttle percentage after complete warmup that it switches to open loop mode. so im cruising at 15% throttle and i smash the pedal and go WOT 100% throttle, at what point does the ecu switch from closed to open.

i really need to get another scan tool and figure it out........

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by plnoldrick &raquo;</TD></TR><TR><TD CLASS="quote">i really need to get another scan tool and figure it out........</TD></TR></TABLE>

I'd be interested in seeing your results. To the best of my knowledge, there is no single set "switch point" from closed to open and vice versa. Instead, I believe the ECU takes a number a variables into account (what specifically these are, I do not know) to determine what mode it employs at any given moment.