supresmooth

I've been reading other posts here on how to troubleshoot this issue, and tried various things without success, so I'm posting here to see what else I can try before I throw money at a new catalytic converter.

I bought this truck in 2006 and it still had the factory cat on it. It was stolen a few months later, and I went with the cheapest thing I could find, which was $150 installed from the random shop down the street from my dad's house. I then moved to Oregon, which doesn't test for NOx, so I have no idea the effectiveness of this cheap cat.

I came back to California two years ago. I put on 32" tires, had my valves done by the local dealership, and my truck passed with these results on 01/06/2015 at 283,668 miles:



In that time, I had a fuel line leak behind the plenum, which I had repaired at a random 4x4 shop. I then went to have it smogged this year and failed with these results on 01/31/2017 at 286,562 miles:



Since then, I have taken it to a reliable shop to have the radiator, hoses, thermostat, cap, and fan shroud replaced (as the radiator was failing due to an improperly installed battery by the dealership in Oregon sliding over into a pulley and spraying acid all over). I then had to take it to a different shop that accepts the state vouchers for smog repairs. That shop replaced the O2 sensor forward the cat and replaced two cracked vacuum hoses, as well as corrected the hoses that were installed incorrectly by that random 4x4 shop. When I got my truck back from the voucher shop, I noticed it ran ever so slightly rougher, and the exhaust now has an odor. I then took it to retest and failed with these results on 3/23/2017 at 286,873 miles:



I reviewed the hose arrangement with the placard under the hood and everything appears correct. I borrowed a vacuum pump and tested the EGR valve and modulator using the methods in this video ( ) and they appeared to be functioning correctly (all things that would have been done by the last shop, but I wanted to check their work). Before the last test, I changed the oil and filter, and it has a new Toyota air filter. I almost exclusively run Chevron regular(typically 87) in it, and have done so as long as I have owned it (only occasionally putting 76 or Arco).

As you can see, I don't drive much. I obtained the truck with 206k miles on it in '06, and put about 30k on in the first two years, but after the battery issue, I avoided lengthy trips with it, and so only put 56k on it over the next nine years. Given that the majority of my trips are short, inner-city ones, and that I don't drive my truck every day, most of what I've read here leads me to believe my cat is gummed up or trashed. Is there anything else I should definitely try or test before trying to replace the cat, since that is gonna be pricey?

Thanks for your help!

atcfixer

iTrader: (1)

Pull your spark plugs and take a photo of them and post it. Keep track which one came from which cylinder. That will give us an idea if it's running rich, lean, or just right for the fuel mixture. I suspect you have a CA emissions truck so not sure what extra stuff is on it. For the O2 sensor, find out what brand was installed, I've read and heard of people having problem with bosh, so I'd say stay away from the O2 sensors. Since the O2 is new, the ECU needs to "relearn" the fuel mapping. The best thing to do is unhook the battery long enough to reset the ECU memory, find a way to drive the truck for 20-30 mins for it to relearn the fuel mapping, and see if it's running correctly at that point. It might be getting mixed results on the test because it's still pushing the limits on each side of things because of the O2 change (spark advancement, air fuel ratio and such).

We don't have anything related emission testing, so I don't directly know what high NOX or HC relates to. I'm just going off the ruff idle and oder (probably running rich, black plugs).

Since you drive the truck a lot in the city, do you really baby it? Carbon build up could be another issue, but getting on the express way every so often generally keeps things pretty cleaned out. I live out in the country, so we don't really have the carbon build up problems.

I'm not super educated on the 3.0L, it's one of engines I know the least about for the toyota pickups/4runners, but it does seem they are a bit picky on things like vacuum hoses and such or else they run weird, and bad mpg follows. I met a guy that completely rebuilt his 3.0L with new heads and all and he gets terrible mpg, like 13 out of his 2nd gen 4runner, and it just doesn't run quite right. No clue what he has going on though since all his vacuum lines are new and everything else seemed right.

supresmooth

I was baby-ing it for a while, because my radiator was insecure. Once I got that thing replaced, I've not been nervous to hit the floor with the pedal, but I've only had a good month of time doing that, whereas I've been driving it delicately for the previous few years.

Here are my gross plugs:



6,4,2
5,3,1

I replaced them with NGKs again, but I just went with the cheaper ones, since I have a feeling I'm going to trash them while troubleshooting this issue.

I had to disconnect the battery for more than the suggested time, because I found that the connector to the EGR gas temperature sensor had broken off one of the wires. Why no one noticed this, including me, I have no idea. I will have to source a Sumitomo or Yazaki wire terminal to complete the repair properly, which will take a while to get. In the mean time, I removed the connector entirely and have the still present terminals clipped together as they would inside the connector, and the other wire snuggly wrapped around its partner terminal, and each branch tightly taped. I used a longitudinal piece of tape to take up tension on the connection for now.

I called the shop that installed the O2 sensor and the mechanic said he installed a Denso. He asked me to bring it by and we put it on the dyno again and it was still failing. That's when I brought it home and started poking around, finding the broken connection and that my plugs were gross.

I also just decided to go ahead and put a new cat on, since the guy down the road does them pretty affordably. Welded on a generic MagnaFlow thinger for $250.

I'll take the thing in tomorrow afternoon for a third test. Here's hoping.

scope103

While the catalytic converter does have a small effect on NOx http://www.cygnusx1.net/Media/Supra/...taTech/h56.pdf , and replacing it may be enough (here's hoping!), high NOx is almost always caused by a problem in the EGR system. That's what it does. That's ALL it does.

A disconnected EGR gas temp sensor SHOULD throw code 71. A non-working CEL should automatically fail smog. For that matter, a competent smog tech should have picked up the broken wire (and failed you regardless of the tailpipe readings.)

Skip youtube, to test the EGR get the right source: http://web.archive.org/web/201003261...77exhaustg.pdf One thing not explicitly considered in the FSM is a blocked EGR tube. The plenum fills with "gunk" (mostly from the PCV system), and can actually put enough of it on the EGR tube to block it completely.

[This is a "sparkling clean" EGR tube; you get the idea.]

The EGR gas temp sensor is there just for that purpose; it's trying to detect the increase in temperature in the EGR tube as exhaust flows through it. A blocked tube SHOULD throw code 71, but your EGR gas temp sensor is asleep on the job.

Let us know.

atcfixer

iTrader: (1)

Looks like the plugs were rich (black buildup under the white?), now it looks a little lean, or about right, hard to tell. In 50 miles or so, pull the new plugs and check them again. If they check out, the EGR makes complete sense, probably a good idea to clean the tubes up well and verify the EGR valve functions and is clear too.

scope103

Note that your 15mph HC is really high (even your passing HC was way above average). In the second test, your O2 started to inch up as well. High O2 (higher than you have) can indicate a lean mixture, high O2 and high HC together often means a misfire.

All of these are muddled if your ignition timing is off, but that's part of the smog test so you should be okay. But for the $20 the right tool costs, it certainly is worth checking off the list BEFORE you start throwing parts.

supresmooth

After all of your help and my efforts, I finally got it to smog with a new cat, but I still needed to address the real issue. Before I was even able to do that, someone STOLE IT last night. I don't even right now.

atcfixer

iTrader: (1)

That's nuts.... be sure to report it to local police and if there's any businesses near by that they had to drive by, try to work with them on video proof to try to track where they went. It's sad but seems even reporting it to the police, you'd get farther working on the case yourself for what you can do.

Hope you get it back in the same shape it was taken from you, and the thief gets a stiff sentencing.

fdp101452

A thief should be shot, survivors should be shot again.