Custom O2 sensor calibration?

[gregp1962]

I have a 1992 corolla. I'm doing some experimentation in improving gas mileage. Does anyone know the best way to modify the o2 sensor signal to reduce the pulse width to the injectors?

[hopeful]

install a resistor in the wire so it doesn't send as strong a signal?

but comeon dude, its already a corolla... maybe you could install smaller injectors..

[gregp1962]

Wouldn't a resistor tell the ECU that I'm running too lean and it would richen up the mixture. Wouldn't I need to increase the voltage from the O2 sensor?

I'm not trying to get better mileage for THIS car to save money. I'm trying to make a new way to atomize the fuel.

[white90dx]

Originally posted by gregp1962
I have a 1992 corolla. I'm doing some experimentation in improving gas mileage. Does anyone know the best way to modify the o2 sensor signal to reduce the pulse width to the injectors?

You don't want to modify the O2 sensor voltage... If you want to run the car lean for better mileage, you need to run the computer off a wideband O2 sensor to get an accurate picture of how the engine is running. A stock 02 sensor on most cars is not accurate except right next to stoich.

If you want to run lean, adjust the engine computer's programming, not the sensors - if you can.

-Charlie

http://auto.howstuffworks.com/question257.htm

[gregp1962]

Is there a way to convert an OBD1 car to a wideband O2 sensor?

I already have an APEXi Super AFC. I'm just concerned that the O2 sensor will fight it while in closed loop. And, I NEED to operate in closed loop.

[thaharlequin]

Get a piggyback ecu thingamabobber.
Like, what is it? EZSquirt iirc...

[white90dx]

Come on guys... you really don't seem to know what's going on with modern EFI engines.

When you are in closed-loop mode on the ECU, your car is running at its best. You can't get any better... stoich=good.

If you want good mileage, just keep the revs low, your cruising speed low, and keep out of open loop fueling.

-Charlie

[OEMonkey]

resistors?
to get to closed loop and stay in closed loop, o2s v signal has to switch above and beyond .45v, not biased one way or the other.

reduced emissions results in increased fuel economy. and one more thing, obd II is not, it is not responsible for any fuel delivery operation. it is merely an add-on emission monitoring system.

[white90dx]

Originally posted by OEMonkey
resistors?
to get to closed loop and stay in closed loop, o2s v signal has to switch above and beyond .45v, not biased one way or the other.

reduced emissions results in increased fuel economy. and one more thing, obd II is not, it is not responsible for any fuel delivery operation. it is merely an add-on emission monitoring system.

You're not quite right about the O2 sensor causing closed loop. Closed loop ecu operation is normally cause by RPM and throttle position.

open loop = good for economy and emissions.

-Charlie

EDIT: I meant CLOSED LOOP... sorry.

[OEMonkey]

Originally posted by white90dx
You're not quite right about the O2 sensor causing closed loop. Closed loop ecu operation is normally cause by RPM and throttle position.

open loop = good for economy and emissions.

-Charlie

sorry Charlie but you're posting wrong information there.
requirements for closed loop operation:
-ect signaling operating temp
-timer has to lapse
-o2s switching above and below .45v
-for obdII- misfire, fuel, and cc monitor all in readiness status. obdI- no cc open/short detected.

engine speed is not a requirement for closed loop status unless the engine is off. you can be in closed loop at idle.
it does require you to NOT be at wot to be in closed loop. at wot, o2s signal is ignored, loop status is open, and youre at full load enrichment. so I dont know where you got open loop=good fuel economy. and since its a richer mixture, hc and co goes up. nox formation decreases though.
the whole idea of closed loop engine operation is to constantly fine tune the afr to keep it at a stoic balance based on signals to the pcm from the o2s and/or other sensors. for what? for fuel economy and reduced emissions. ever wonder why the evap and egr system are only actuated during certain closed loop conditions?
also if you think you get better fuel economy in open loop, then just disconnect your o2s and try to keep your throttle position at 75% or more all the time and put a low resistor on your ect connector for full time cold enrichment.

[white90dx]

OEmonkey, I appologize. When I said open loop, I meant closed loop. Your corrections to my statement are correct. One minor semantic issue - closed loop operation uses the 02 voltage to adjust fueling, so the switching of the voltage itself does not cause closed loop, its a byproduct of it.

As a side note, there are at least two versions of 'open loop' - the performance mode (high throttle position and rpm) and safe mode (when critical sensors are disconnected or malfunctioning). Neither of them are good for fuel economy. Heh...

-Charlie