What have you done to your Tacoma today? 1st Gen Edition

yeah that's how my issue started, very similar...code came up pending the first few times, cleared it with my scanner and was good for a month or more early on. Then it started coming up as an actual code, cleared it once and it came back and I knew I couldn't ignore it any longer lol. Especially when I started noticing performance issues.

I had myself convinced early on that it was due to a bad tank of gas because I first got the code after I filled up at a 76 station in a rural town north of the city, I have to run premium and I figured maybe there's was old since they probably don't sell much of it up there. But it was just a coincidence and I relied on that assumption until it got bad enough that I took it in to have a shop confirm it was the cat.

For some reason there are many P0420 threads on TW and a lot of people like to be in denial about their cats being bad, even though the code practically spells it out as being a bad cat converter lol. The exhaust shop that fixed it for me told me that if they see this code and there are no leaks, then the cats are to blame. Bad O2 and a/f sensors will throw separate codes.

 

Good to know, I suppose. I was also leaning towards the bad gas syndrome considering the places I've fueled up at in the last year. I run 87oct and have seen mileage fluctuate +/-4mpg depending on wind and rain, granted these are 1000 mile runs. If it looks shot I may just gut it and space the rear o2.

 

I definitely dont want any super wide tires. Im still leaning toward the (option 1) 285/75/17. thats an actual size of 34.06" x 11.1" compared to the (option 2) 295/70/17 @ 33.45"x11.6" or the (option 3) 255/85/17 @ 32.8"x 10.1". What I like about option 3 is they will fit better and cost $80 less a tire. But a bigger tire would be nice!

 

Shit I've had an intermittent p0420 for a couple years now.

 

pending or actual code? You haven't noticed any performance issues?

I had to get mine taken care of because of CA emissions inspection...we have to do it every other year and can't have any codes, pending or otherwise, stored in the ECU...or we can't get registered.

 

An actual code. I always thought it was the post cat 02 sensor. Funny thing is I can clear it and be good for hundreds, sometimes thousands of miles till I put it in 4 low again. That seems to trigger the code to come back. Or it can be the shit I go through in 4 low (water crossings, etc). I remember @ToyRyd04 and I having the discussion back in the day of getting the URD thing to basically trick the sensor but forget the actual details. FWIW it's likely the original cat on a truck with 235k on it. No performance issues that I have seen aside from only getting 15 mpg on the V6 but I always attributed that to the massive quantities of armor on the truck + dirty5's. Also need to do some maintenance that might make those numbers improve.

 

yeah mine would always come on for sure if I went offroading in 4lo. Sounds like yours hasn't gotten too bad yet. Only thing I'd worry about possibly being an issue with not getting it fixed would be if the ECU is compensating for the bad cat in a way that could hurt things in the long run, performance issues being a byproduct of that. Worse MPGs, too much/too little fuel, etc. I'm not well-versed on that but maybe someone else can speak on it.

I did have a P0136 code (bad rear O2 sensor) not long after the P0420, presumably because that sensor was getting roasted because the cats weren't doing their job effectively. When I pulled it out it looked like it was in a forest fire lol.

 

If I understand correctly, I can 100% diagnose the bad cat by watching the O2 sensor readings. If the front is jumping reading lean and rich and the back is reading similar and jumping, then the cat has gone bad. The rear sensor should stay fairly consistent if everything is in working order. Am I understanding correctly?

I haven’t noticed in performance issues, other than it cutting off the other day. The idle has been a little off sometimes it will idler higher than it should, but I attribute that to probably needing a TPS or IAS

 

What cat did you get to replace it? If I did it, I'd like to keep it on the cheap side

 

Magnaflows...I was told by more than one person that if you can't do OEM ($$$$) then go with Magnaflows. I had to get their CARB compliant ones which cost me $600 for both front and rear installed by a local exhaust shop. Toyota wanted nearly $3k to install both OEM.

Magna flow makes even less expensive options if you don't need them to be CARB compliant

 

yeah that sounds right, I know there are other ways to check the cats yourself such as the processes described here https://www.youtube.com/embed/kNXh1Lphzr4

 

Yup, had the same thing happen two different occasions. 1st time, truck was still under warranty and actual the first cat fell apart inside clogging the second cat. (~$1700 covered by the Dealer). Second time it happened, I decided to hollow both out, theyve both been hit so who knows if the cataylst inside had been broken again. Then picked up https://www.urdusa.com/urd-rear-o2-simulator-5vz-fe-3-4l-v6/

You still need the both sensors, Front is MAF rear is just a normal O2 but is needed in good working order for this simulator to pick up the reading and adjust accordingly to not throw a CEL light.

Had mine for quite a while now, 6-7years?, 10min install and passes every 2 years when MD has emissions tests. And 1996 and above vehicles do not need a "sniffer" style test to pass, just a simple plug up and test via OBD2.

 

damn I didn't know URD sold those for our trucks, just thought they were for 2nd gens.

 

Yep, nice plug n play setup underneath passenger side seat carpet out of the elements. Been super reliable without any issues.

 

they made that for our trucks before any 2nd gen version by a long ways haha

 

Lunch break. I'm making progress. Got the drive lines off, the shift levers off, and all (I think) of the wires disconnected.

 

Out with the old, 2 spoke which I hated.



And in the the new (old) 4 spoke which I much prefer. This one is from a 1999 SR5 4Runner so hopefully the cruise will still work. Haven't tested it yet. I did have to swap the airbag inflator thing since the plugs were different.

 

Was this essentially plug and play aside from the inflator? My gf’s 98 4runner needs a new wheel

 

Yup. And in your case, you probably won't have to swap the inflator module, unless they changed it from 98 to 99 on the 4Runners. And the cruise should definitely work. I still need to test that in the Tacoma.

 

Did you swap the airbag squibs?