has anyone went into depth regarding the closed loop subroutines?reason i ask is iv been wondering about closed loop fuelling and i wondered if the target value the ecu looks for could be altered instead of altering the closed/open loop threshold points.

 

If you want to do a Lean Burn type of thing it would be easier to run Full Time Open Loop and alter the fuel map.

You can alter the Front O2 Switch Point, stock is 0.51 volts or something.
But a Narrow Band O2 Sensor is designed to work in a very narrow AFR range so it won't work correctly if the switch point is too far off middle(0.5 volts).

 

Doesn't running a simulated wideband output into the front O2 with an AFR offset do essentially the same thing as targeting a different AFR in the feedback routine?

 

What 03whitegsr said; if you really want to keep closed-loop, simulate the O2 signal with your wideband, and adjust the output accordingly.

 

yeah i know about running an anologue output from a wideband but i was wondering if the location had been found and if anyone had played with it.i know the narrowband has a limited range but i assume it would not take much of a voltage change to alter the closed loop afr in cruise and idle.

 

Required reading: http://www.aa1car.com/library/o2sensor.htm. Specifically, the chart labeled "Oxygen Sensor Switching Voltage":



A narrowband sensor can only accurately measure 14.7:1. Period, full-stop. Nearly the entire output voltage range is dedicated to reading that value, give or take a point. As soon as it steps away from that narrow range, the results diverge wildly, and resulting readings will almost certainly not be repeatable.

Use the right tool for the job. If you want to read something other than 14.7:1, get a sensor that can accurately read the values you're interested in. For us, that typically means a wideband sensor.

 

Not exactly. The ECU expects to inject X amount of fuel for the airflow to hit 14.7 AFR. If you run a WB to simulate the NB and try to target, say 15.3 AFR, the car will end up adjusting to that point using the fuel trims. Suddenly your fuel trims will be off. The trims will all go negative trying to pull fuel.

A patch was put out to correct the expected fuel demand inside the ECU. I'd like to see it in then next round of Tephra mods. (Hint, hint )

 

thanks for that.makes alot more sence.