I ask this before but you never answered. Can't help without info, GIGO

 

i am currently getting a P0420 code, and i have a working rear O2 sensor after the first cat, but no sensors before or after the second cat (stock). so here is what i want to do

replace the first cat from the headers (upstream) with a new high flow (the 56$ one on ebay) and get the urd sim, will i keep throwing the p0420? while im at it i would want to just remove the second cat from the headers (downstream), at first glance, i couldnt see any sensors before or after the downstream cat. i have the a/f sensor before my upstream cat and an o2 sensor after the upstream cat

so basically from what i can see, toyota just put another cat downstream of the actual cat back system to make it cali legal.... so if i just remove that second cat, how is the engine going to know that anything is different?

 

Hummm....that's interesting, never saw one like that before. I think I'd try moving the rear O2 sensor behind the 2nd cat and see if that takes care of the P0420.

The other plan should work fine though that's exactly how I'm running right now and it hasn't thrown a P0420 since I installed the URD O2 sim.

 

Take a picture of the system and show us. I never saw a system with no 02 sensor after the last Cat. So let me clarify what we know. You have an O2 sensor before the 1st cat, then you have another cat and no sensor behind it . Is it possible it is missing ? and thats why you are getting the code. We need pictures.

 

I find it very odd that you don't have any sensor behind the second cat.

I fought this whole thing for months a year ago or so. I removed my rear cat, left everything the same and installed the URD O2 Sim and haven't looked back. You won't throw any codes after the sim, or you shouldn't anyway.

Definitely verify that you don't have a sensor behind the second cat because that will dictate what you have to to tie into for the Sim.

You may also want to email Gadget and let him know to be sure the Sim instructions will reflect your situation.

Good luck!

Fink

 

Here's a link to my thread...it's a long read, but a good read.

https://www.yotatech.com/forums/f2/d...runners-67521/

Hope that helps,

Fink

 

thanks for that link, it was a very informative read, i just have a few more questions

okay, i looked today a little better and i do in fact have another O2 sensor behind the downstream cat. so then when i remove the second cat, i will have two O2 sensors downstream of the first cat. does this mean i need two O2 simulators? do i just put the O2 simulator on the first one or what? did you have two O2 sensors after your cat? you did report more power and mileage correct? thanks again guys for all your help. looks like i might get out of this one for cheap!

 

Ya know, I honestly don't remember what I had them do. I think they cut off all of the cats and just put one high-flow cat in and left the sensors where they were and then I installed the simulator.

I noticed a slight (.5-1mpg) different in mileage and a little bit better throttle response after the removal of the cat.

Hope that helps you, good luck!

Fink

 

NOOOOOOO! You will have one before the first cat and one after to measure the efficiency. I still don't see the problem . Make it one big High flow cat and put an 02 sensor about 6inch after it and then add the sim later if you throw the codes.

 

hey fink, can you take pictures please? im not sure which O2 sensor i need to put the sim on.

 

You shouldn't need pics...it goes right next to your ECU behind your glovebox.

You don't even have to go underneath the truck if you don't want to...the instructions that come with the Sim will tell you what to do and which wires to splice. The only sensor you're concerned with is the rear one as it is a Rear O2 Sensor Simulator.

Let me know if you need more help.

Fink

 

okay, sorry but for some reason i was thinking i had 3 sensors, one before the first cat, one after the first cat and one after the second cat. when in fact i only have one before the first cat and then one after the second cat. so i geuss i just order the sim and install that... i kinda want to remove one of those cats though.... we will see what happens with that. thanks again guys for all your help!

 

i hope this helps but uh, the first cat on the cali em. is a cold cat. it cuts smogs @ low temps (which is why it cost u an arm & leg). second cat is a regular cat which operates @ higher temps. also there are 2 sensors for a cali em. the one closer to the header is a air/fuel ratio sensor. the ladder is a regular O2 sensor. replacing two cats with one only gives u 2~5hp boost (not worth the trouble if u ask me). i only know this because i had to get all of the above replaced. i found the front cats online for less than $80 online with shipping (not cali legal). i dont remember the site tho, it was about a year ago. no check engine lights still.

 

So you're saying that you replaced both of your cats, kept them in the stock locations and left the sensors in the stock locations with no sim and you haven't had any problems?

That'll be the first case that I have heard of like that.

The Sim was a really easy install, took me about 30 minutes doing it the right way and I got a power boost out of it all and better mileage.

I'm glad it worked for you though, that's pretty cool.

Fink

 

now thats what im talking about, if you had a link to the front cats for $80 you would be my hero.

 

agreed

 

so im pretty much settled on the sim, but my question now is, how do i do this properly. (im going to write down the steps so you can correct me if im wrong)

1. remove both cats
2. replace with one high flow cat
3. put simulator on downstream O2 sensor


now while im doing this, do i need to have the exhaust shop move any of the sensor bungs? or leave them in stock location? which position do i put the new cat in, up stream or downstream? thanks again

 

As far as the steps go, that sounds right. Techincally you can do it in any order you want. You could install the sim first and then remove the cats or the way you have it listed, entirely up to you, my friend.

As far as where everything needs to go...doesn't matter one bit. Once that sim is installed, you could remove both cats and run straight pipe, while illegal in most places, it would still work. The sim will fool the ECU no matter what configuration you run on the actual piping. Does that make sense?

What I think I had them do was remove both cats and install the high flow about 8-10 inches away from the downstream O2 sensor. It really does not matter where you put it though.

Hopefully that answers your questions.

One piece of advice, take your time and be very sure of the wires you are cutting on the ECU. If there is one little thing that doesn't match up between the sim's instructions and the color of wires on your, ECU stop, and don't cut anything. I made that mistake, it ended up being that I had an old version of the instructions, this problem has since been fixed. I would check all colors and location numbers of your ECU wires against the descriptions on the instructions before doing anything, if they match up, then go for it...if they dont, email Gadget or get on here and post up. I'll be sure to check back often in case you have a problem or you can email me at cfink@anbfinancial.com

Just my $.02, good luck,

Fink

 

alright i just ordered the O2 simulator from URD and got the priority mail so hopefully it will be here before the weekend! then i will go ahead and install it to get rid of the check engine light and TRAC/VSC that brighten up my dash. then hopefully next week sometime get it in the exhaust shop to remove both cats, put a high flow on it and maybe a new muffler while they are at it. thanks guys for the help so far and ill update this thread with my results as soon as i get them. thanks again guys.

 

Good luck man!

Fink