Just an update on this circuit. I built a virtual one on one of our development systems (just a hardware DAC hooked up to labview) and plugged it into the car. It does work - albeit not exactly how I want as I'm still waiting to see if haltech will make the necessary adjustments to their firmware. If not then I'll build a small board with a micro on it so both O2 signals can be modified. If I get exceptionally motivated I may add a wideband circuit on it as well but if I did decide to do it and sell I'd end up paying licensing fees for the WBO2 circuit.

 

emulating the front sensor would take a little more work, at least in my head, as the ECU expects it to error out under certain conditions where the rear sensor is supposed to function the same under all conditions. for example, under WOT the AFR goes from ~stoich to richer than the narrowband sensor can read so the front sensor shows a constant while the rear sensor (as long as the cat is functioning) shows the normal voltages.

 

Both sensors should be narrow band unless I misread the shop manual before christmas. I can ask a few emissions systems guys what they generally expect the front -> rear O2 to do. In the past I've seen a simple circuit added to an O2 sensor to stop it from throwing a cat inefficiency code.

 

they are both narrowband, but the front one can't read past a certain point (hence narrowband) and in my logs at WOT it ends up around 1V. not sure what the ECU would do if you weren't able to emulate a WOT condition; maybe nothing

the rear one should be as simple as the circuits posted, as long as the ECU doesn't expect small variances. not sure what the second one looks like because I wasn't logging from it until after I started getting an innefficient cat code

 

pretty cool stuff dan! I have three codes, too much emissions from rear O2, and front O2 sensor and heater circuit not ready. My front O2 sensor is out and in its "bung" I put my wideband. I put the narrowband simulation wire of the wideband directly into the ECU where the front O2 input wire should go, the car idles and runs at 14.7:1 but still doesnt think there's a front O2 sensor. Any ideas on how to fool this code?

 

What are the exact codes you're getting? P0what?

 

what wideband? did you snip the o2 sensor off the harness?

 

Hm.. looks like I'll revive this one. But basically my setup is as follows:
Front O2 sensor was replaced with a Innovate Wideband O2 sensor and I used the narrowband output on that unit to plug into the ECU.
I left the O2 sensor to hang or well be exposed strictly because I needed the heater core. My question is Dan mentioned a way to simulate the heater core but never elaborated on it. Anyone else try this yet?

And yes I get the P0171 Bank 1 Lean code still, I think its because I have the 2nd O2 sensor spaced out too much from the pipe so it doesn't read enough emissions in general.

 

you are still getting bank one lean? are you using analog one default settings? what are your wideband AFR's looking like? bank one implies o2 one, and o2 two is for cat efficiency readings, so I doubt it's your second o2 sensor causing the code.

you have to measure the resistance of the heater coil and get a resistor with a high enough power rating (wattage) to dissipate the heat instead of burning up the resistor. I think 25-50 watts was mentioned.

send me some logs and your piggy map(I can't figure out which one it is, I don't really have any need to keep track of them that well ) and I will see if I can get rid of that code for you... if your piggy map is too lean of course.

 

so has anyone actually built this 02 sim???

 

yes, but not for the RA.

EDIT: not to imply that I have. I found it on another forum

 

Well I'm just looking to simulate the heater core.. if not I'm fine with the CEL up until inspection...

 

that's the one I need, so if you find a place to get that resistor for cheap let me know

 

How much resistance does it need to provide. I might be able to order em' through work. We run resistors that are the size of hot dogs during our electric durability tests...

 

The O2 sim does not work on the ralliart.

For simulating an O2 heater they don't bother measuring the current or anything like that. I simulated the front O2 heater with a 1K resistor - it's a ground driven circuit so run the 1K to a 12V source. The error circuit just looks for the output to be pulled up to 12V. I did not throw a CEL during the test but with the resistor unplugged it did so I assume without further testing it did work.

-Michael