Good Morning Rorschach,

I would try clearing the code(s) before shelling out money for a converter.

Even if you have to clear the codes a couple of times I still think it is worth a shot.

You still have better than 8 weeks until December so you should be OK time wise with this experiment.

Good Luck - KJK

Let us know how toy make out on this!

Do you have to do regular emmisions tests?

On a couple of my old workhorse vehicles which I never needed to take to DEQ, I simply removed the Cat, bashed it clean out, and stuck it back on. Worked like a charm, increased mileage, horsepower, and made em sound great. But this is strictly a backwoods solution.

_{Did I just say that out loud?}

'fraid so RVZ... they plug in the ODBII cable to the ECU and read out all the sensor info and codes every year in Texas.

Good Point RV,

Not too many moons ago (but enough to be prior to all the high tech gadgetry of today's vehicles) I did the same and it worked like a champ.

Regards - KJK

After rooting about on the interwebz, I have found that direct bolt-on replacement Cat Converters can be had for about $140, so the sting of replacing the unit is somewhat reduced (but I've already sunk over $1300 into this truck in the last two months trying to solve this problem!). They sell some universal fit ones marked for off-road use only for as low as $60. I presume they have less catalyst and more flow area and don't meet EPA guidelines for a road vehicle but lower the engine back-pressure and don't get as hot (and therefore are likely to cause fires in tall grass.). but If I can get the thing to pass inspection with one I might be tempted to try that. anyone think that might be possible?

A combination of online discounts (20%) that expire today, and a rebate from the manufacturer ($40) plus the list price of $130.99 for the Cat Converter bolt on replacement convinced me to go ahead and pull the trigger and buy the parts. looks like I'm doing exhaust work this weekend...

Repair Rules

• Chapter 114 of the Texas Clean Air Act requires that a missing or failed catalytic converter or other failed pollution control device must be replaced with one specified for that vehicle and which has been certified by the federal Environmental Protection Agency. The repairs must meet the emissions standards established for that vehicle. It is also illegal to add equipment, such as a turbocharger, that wasn't originally certified by the manufacturer for that make and model.

Exemptions

• Texas law exempts vehicles and engines used exclusively for auto racing, research and development, or vocational instruction. It also exempts farm vehicles made before 2000, and vehicles or engines being exported from the United States.

Read more: Catalytic Converter Laws in Texas | eHow.com http://www.ehow.com/list_6972780_catalytic-converter-laws-texas.html#ixzz1ZSmyzFbK

So since it's a 98, which is pre-2000, its exempt (Just put some hay in the back)... you could also say it's for research... of some kind, I'm sure you could come up with something.

Not that I would recommend anything illegal, or slightly bending the laws... but...

Let's just say that the EPA is not exactly real popular around these parts right about now anyway...

In Texas, you can register your truck as a farm vehicle, and the taxes are reduced (and few people check it I am told.), but now the Feds are requiring you to have a CDL to even drive a tractor on your own land, so that might end up biting me in the arse if I were to try that....

Here, you can drive whatever you wan whenever you want as long as it's on your own land. I can have my 5 year old daughter (or Labrador Retriever) drive the CAT if I want, as long as it's on my land.

Now... Where can have my dog trained to operate a 18 wheeler??? Perhaps it's a job more suited for a Feline?

RVZ, not if the USDOT has anything to say about it.

http://www.dairyherd.com/dairy-news/123857449.html

"off-road farm equipment or implements of husbandry operated on public roads for limited distances are considered commercial motor vehicles, and therefore, must drivers obtain a commercial driver's license?"

That says "operated on public roads". I'm talking about a tractor never leaving my property, which it says nothing about. And that's also specific to Agricultural farms. If I just had some nice property, and chose to play with big boy toys, that's still my own deal, which no one has any say over.

I doubt the feds will be interested in splitting that hair. But YMMV...

YMMV?? Haven't seen that one before... what's it mean?

Just looked it up... Your Mileage May Vary?

Yup!

Now... Where can have my dog trained to operate a 18 wheeler???

Lyn-Door School for Canine Professionals. "They are dog gone good"

Why would you need any driving proof if you remain on your own land?

give us a break lyn. some of us are just trying to get by.

Other then a bad catalytic converter those codes has a faulty oxygen sensor posibility.

http://www.obd-codes.com/p0420

http://www.obd-codes.com/p0303

That's a good point, A faulty sensor will throw the same code as a faulty Converter. I believe there is a way to test the sensor with a multimeter, but I don't know the specifics... might be worth a shot... however, the CAT does wear out over time, especially when a misfire has been occurring.

Yeah, I asked the Mechanic about the possibility that the O2 sensor being the culprit and was assured that it HAD to be the Cat Converter. since the cat converter is not instrumented, the only way the ECU could determine how well it was working is the O2 Sensors. so I am not so sure I believe the Mechanic. I have a ODBII data dump from this morning that i'm going to try graphing this evening and compare the two O2 sensor readings against the spark advance and see what the graph shows. i also cleared the code and i'm going to drive it a bit and see if it comes back. I may end up returning the parts I just bought online. I'm also told that looking at the short term fuel trims is a good way to determine if the o2 sensors are bad, should not vary more than +/-5-10% I am told.

Pull the cat, make it loud and if the code pops back up its the O2. Now really though the O2 sensor readings for hot and cold are published in the Toyota repair manual and can be read with a OHM meter or O2 meter your mechanic should have which would rule it out.

I say do it like the good ole days a little gas in the bottom of the Corvair turbo muffler and a welding torch always blew out packing and increased flow and made great sound for me.

I have used store bought converter cleaners. (do not but the crap from Lyn-Door Industries) I have also used water through a vacuum hose to clear out deposits. Use the thinnest vacuum hose, and raise the engine speed to around 1800-2000 rpm (no exact speed is necessary, just manageably fast) Let the vacuum suck the water out of a 16 oz bottle and do not let it stall. The idea is to just slow the engine down a little with the water. As the water is finished, the engine speed will return to the faster speed. do this twice, and then bring the speed back to normal and drive it and check for codes. The water usually cleans up the O2 sensors and the cat(s) pretty well. And cheaply. Good luck.

If I remember correctly, there are no sensors after the single cat on your truck. That means that the computer never knows what is going on in the cat(s). If the cat gets plugged up, the engine will develop back pressure as the cat becomes a choke to the engine. This can be seen with a vacuum gauge as road speed is increased slowly. Or, just create an exhaust leak in front of the cat, and watch the performance change. Again, good luck.

Well, it is too late for me, I went ahead and replaced it, only had to saw two of the four bolts off.... but I'll keep that in mind for the next go-round... That said, there IS a second O2 senor behind the cat on this vehicle.

it's the oxygen sensor. sorry if i restated another post.

That would not appear to be the case. So far, since replacing the cat converter the truck has not given a hint of trouble.