Rear O2 sensor trick?
02-17-2020, 12:39 PM
#61
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I would interpret it as a different way to basically get the same result. You could remove the cat entirely, and a passive filter would still work (assuming the correct parameters).
It would depend on what DTC(s) you get. For instance, if you try those values and still get P0420, maybe try to decrease the break frequency (use a larger C and/or R). If you get some other code, you'll need to figure out the cause, and adjust accordingly. It helps if you can log the data and run simulations so you can see what is going on. One other thing to consider is the impedence of the ECM. I measured mine to be only around 1Mohm, so I had to be careful about using too big of a resistor or O2 sensor voltage at the ECM would be too low (because of voltage divider effect).
I'd try the 200kohm/10uF, and go from there. These are both Toyotas from the same era, so I'd think things would be similar. If you still get the P0420, maybe try 200kohm/20uF or 500k/10uF and see if that kills it.
It would depend on what DTC(s) you get. For instance, if you try those values and still get P0420, maybe try to decrease the break frequency (use a larger C and/or R). If you get some other code, you'll need to figure out the cause, and adjust accordingly. It helps if you can log the data and run simulations so you can see what is going on. One other thing to consider is the impedence of the ECM. I measured mine to be only around 1Mohm, so I had to be careful about using too big of a resistor or O2 sensor voltage at the ECM would be too low (because of voltage divider effect).
I'd try the 200kohm/10uF, and go from there. These are both Toyotas from the same era, so I'd think things would be similar. If you still get the P0420, maybe try 200kohm/20uF or 500k/10uF and see if that kills it.
02-17-2020, 12:41 PM
#62
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Weird - not sure why the rest of my post didn't show up, but this is what I wrote:
ETA: guess it did post. The simulator is just a different way of doing the same basic thing (fooling the ECM into thinking there'sa working cat).
ETA: guess it did post. The simulator is just a different way of doing the same basic thing (fooling the ECM into thinking there'sa working cat).
I would interpret it as a different way to basically get the same result. You could remove the cat entirely, and a passive filter would still work (assuming the correct parameters).
It would depend on what DTC(s) you get. For instance, if you try those values and still get P0420, maybe try to decrease the break frequency (use a larger C and/or R). If you get some other code, you'll need to figure out the cause, and adjust accordingly. It helps if you can log the data and run simulations so you can see what is going on. One other thing to consider is the impedence of the ECM. I measured mine to be only around 1Mohm, so I had to be careful about using too big of a resistor or O2 sensor voltage at the ECM would be too low (because of voltage divider effect).
I'd try the 200kohm/10uF, and go from there. These are both Toyotas from the same era, so I'd think things would be similar. If you still get the P0420, maybe try 200kohm/20uF or 500k/10uF and see if that kills it.
It would depend on what DTC(s) you get. For instance, if you try those values and still get P0420, maybe try to decrease the break frequency (use a larger C and/or R). If you get some other code, you'll need to figure out the cause, and adjust accordingly. It helps if you can log the data and run simulations so you can see what is going on. One other thing to consider is the impedence of the ECM. I measured mine to be only around 1Mohm, so I had to be careful about using too big of a resistor or O2 sensor voltage at the ECM would be too low (because of voltage divider effect).
I'd try the 200kohm/10uF, and go from there. These are both Toyotas from the same era, so I'd think things would be similar. If you still get the P0420, maybe try 200kohm/20uF or 500k/10uF and see if that kills it.
Last edited by leaver_red_jr; 02-17-2020 at 12:44 PM.
02-17-2020, 12:45 PM
#63
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No problem. I hope you get the issue resolved.
02-18-2020, 07:23 PM
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So if I can't easily source a 200K Ohm resistor, I can easily just use 2 100K's, or any number of resistors valued to equal 200K, in series, right? Or if there's like a 220K ohoh available, that's not going to be an issue? Same with the capacitor within like 1-2 uf?
02-19-2020, 12:29 PM
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Yeah, that should be fine. Digikey definitely has the 10uF (445-174239-1-ND) capacitors and the 200k resistors (BC3256CT-ND) in stock now though. Both of those parts are rated for automotive use, so if you go with something else, I'd try to make sure it's comparable in that regard.
02-21-2020, 12:26 AM
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The last order that I placed contained 15 resistors and 10 battery contacts. The shipping charge to Berkeley, CA was $3.75. You can usually choose USPS first class for small stuff, and it's pretty cheap.
02-22-2020, 02:24 AM
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Yeah, that should be fine. Digikey definitely has the 10uF (445-174239-1-ND) capacitors and the 200k resistors (BC3256CT-ND) in stock now though. Both of those parts are rated for automotive use, so if you go with something else, I'd try to make sure it's comparable in that regard.
02-23-2020, 01:09 AM
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I was mainly concerned that they have AEC-Q200 rating and that they'd be physically small enough to hide in the O2 sensor harness so that a smog tech wouldn't notice anything.
02-23-2020, 04:31 AM
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02-23-2020, 11:29 AM
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500?
Hey, in your original post title, you stated using a 500K ohm resistor but at the end there you said to use a 200K. You say I should use the 200K ohm resistor and the 10uf capacitor right?
03-01-2020, 05:13 PM
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Bump
hey, figured you maybe didn't get an alert cause I didn't quite your post. Just seeing if this helps any.
03-03-2020, 06:35 PM
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Sorry about that - 500k was a mistake in that post (will edit), definitely used 200k ohm resistor. The 500k worked for the P0420 code, but it triggered the P0136 due to too little voltage swing.
03-04-2020, 01:33 AM
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Awesome
the damn CEL turned OFF!!! AFTER being on for a few months now.
03-04-2020, 01:26 PM
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When my CEL first started coming on, I'd reset it and it would stay off for quite a while. After a few months, it got to the point where the system would not pass the readiness check and the CEL would come on right away.
03-04-2020, 02:39 PM
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ya, it's weird. I'm sure it'll come back on probably sooner than later. But, it's off for now so if it does come on, I'll be adding the components to the oxygen sensor wires.
03-05-2020, 02:12 PM
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An odd situation
04-16-2020, 10:59 PM
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Help finding other cponents
just had my damn CEL turn on once again and I don't think she's turning back off. So I'm ready to bite the bullet and do this damn thing. But to make the shipping worth it from Digikey, was going to order the 500k ohm resistor and additional 20uf capacitor but upon searching, I'm really having trouble finding them, and am getting very limited results and in minimum orders of 100. I just wanna be sure they're AEC-200 compliant like you mentioned, so was curious if you'd be willing to post the part #s to enter into digi key for these extras so if the first combination of 200k ohm res and 10uf capacitor doesn't fly, I can fiddle with the other 2 combos you suggested? Would you maybe get back to me here if you get a second. I'd really appreciate it. Thanks a million.
_Airwalk.
