O2 Simulator

Also, FYI I just read up on 02 sensors and their signals. The expected output is an analogue voltage, not a PWM signal like a lot of other things are. If what I read is accurate, the ECU goes into an open loop until things come up to temperature and then it goes into a closed loop using the varying voltage from the sensor.

0.1V is as lean as it can read, ~0.45v is a perfect 14.7:1 mixture, ~0.9 volts should be super rich

YMMV I'm r-worded

Also, shouldn't you have two O2 sensors since you use OBDII? Are yours single wire, or the heated type?

 

Wideband (AFR) should be analog, Narrowband should be PWM. You're correct about open loop. WOT also causes open loop after its at operating temp.
Heated, yes there are two, but as long as the downstream isn't completely out of sync with the first, it shouldn't require spoofing. ECU relies on the upstream for corrections. Disconnecting or fooling into never up to operating temp works for a few minutes max, then it freaks out and starts correcting based on some indeterminate factors for about 20 seconds, then throws CEL and reverts to open loop. Basically that 20 seconds is what I'm fighting here. Yes you can try to time that to occur when you're stopped, and maybe I'm unlucky, but it seems like it only likes to run its check under load. Issue is compounded by the fact you have to turn off the engine every time you make map changes on the Split Second.

Thanks for coming to my TacoTalk™

 

Without scoping the signal or finding it somewhere in the FSM... I dunno lol. It'd be just a shot in the dark.

So if you just set a constant signal, what happens?

 

I would read through that thread I linked, a lot of the same discussion happened over there

 

Yeah, it took them a while to get to anything worth reading, but it seems like 1 second pulses at the O2 sensor voltage seems to work for most people. Something like a 1M resistor and a 4.7uF capacitor. There was even a guy who did a capacitor and a diode to drop the voltage to .5v. So problem solved? Thanks for the good read by the way.

 

Does the whole thread focus on the rear O2 sensor? From the first post it sounds like they're just doping the response of the rear to make it think the catalytic converter is working at full efficiency.

I did see some of their waveforms but I'm just gonna probe my own since I know mine work properly; I have a Siglent, I just need to put my mind on doing it.

 

Yes and yes. Their goal was to generate a signal that would simulate a relatively perfect burn. I think that since their method just bounces around the expected values of a clean burn without deviating too far, the computer generally accepts it. I'm willing to bet that the people who couldn't get this method to work did something wrong.

 

Yaaa... Totally a secondary issue for me..if at all. I can't really remember what exactly the URD simulator did, but I was pretty sure it was for the front bank and it worked in conjunction with the FTC to artificially control ECU-seen AFRs, so that when it hit a rich cell in closed loop, it wouldn't lean back out.
Those people actually need to get their cats changed lol. P0420 isn't just a failed sensor, it's actually telling you you have a bad cat.

 

Yeah, they're cheaping out in that thread. The front sensor shouldn't be hard to do. Could even use a microcontroller if you're brave.

 

That's plan B

 

HMU if you go that route. I have some experience pixie wrangling.

 

Just @ me next time

I got the URD sim because of my P0420. I know my cats are getting old, truck has 200k+ miles, but I'll keep running it this way until I fail the sniffer test. By then, the truck will probably be an off road toy only.

 

We still love you, bru. No shame in that game. I don't deal with emissions checks in my state and if I had to put up with some of the crazy stuff the CA guys do, I'd pull the same stunts.

 

Just wondering if yours shipped? I ordered one the same day as you, got a tracking number but it looks like it was never actually shipped out.

 

I just checked and it says it was delivered today the 31st!

 

Nothing like discussing a Federal Crime on the Internet!!

 

My downstream O2 sensor just hangs out smelling the fresh breeze. No codes. Am I just lucky?

 

It could possibly be either one. The best way to find out is get a scan tool and monitor the downstream 02 sensor with the simulator plugged in and without it plugged in. Because you have one cat in place it may make this diagnosis more difficult. The upstream should be switching from approx 1v-0v. If your downstream is mirroring your upstream, with the simulator unhooked, that would that will let you know that the oxygen sensor is good, but the converter is bad. Your o2 sensors produce a voltage, and it is my understanding that the simulator is just a voltage regulator. Under proper operation of the converters, your upstream will be switching 0v-1v, and your downstream will be around a constant 0.5v.
If the upstream and downstream sensors are mirroring each other, that will set the p0420 code.

 

Didn't know that until now, thanks your honor