04 Tundra NO emissions failure

Hello gang, I hope you experienced techs can help me with this issue. I purchased a 2004 Tundra V8 4WD with 215k miles on it. When I purchased it, the check engine light was on with a P0420 code. Before I could address the issue, I ran through one of the roadside detectors in Northern VA and it failed the NO test. Everything looked aftermarket under the truck, so I ran the full gamut. I replaced all 4 O2 sensors and of course, the studs snapped off so I had to replace the cats as well as the resonator and the muffler. With that being said, the exhaust system has been replaced from the manifold back. Even though the check engine light was on, the truck purred like a kitten. After replacing the full exhaust system and driving the truck for over 100 miles on the highway and in the good ol' bumper to bumper traffic in NoVA, I took it in for an emissions test. It failed the NO test again. (See emissions report) Hopefully you guys can help me out. I really like this truck, but the Commonwealth will not let me drive it if I don't get this emissions issue resolved.

 

Hopefully, someone here can assist with your issue. Keep us posted with your results.

 

Welcome from LA (Lower Alabama)! You'll get a much better response if you post your question to the Ask The Toyota Mechanic thread:
https://www.tundras.com/threads/ask-the-toyota-mechanic.2404/

 

Thank you...will do.

 

Which cats did you go with? Aftermarket cats are usually borderline passable even new.

 

That could possibly be part of the problem. I went with a set of those cheap Canadian cats from Ebay. (See link) FITS: 03-04 TOYOTA TUNDRA 4.7L PASSENGER & DRIVER SIDE CATALYTIC CONVERTER SET | eBay

 

Since most of these trucks have Cali spec emissions your pretty much forced to get 50 state cats to make the computer happy

magnaflow was the only aftermarket I had luck with on my Tacomas.

 

Based on the EBay posting, these cats are compliant.

 

Was it up to full operating temp when it got tested?
When I tried to get my Raptor 660 atv smogged to register for on road use in AZ, I had to run it pretty hard in the lot nextdoor to the testing facility to get the engine nice and hot before my NO would drop down.
Cats need to be nice and warm before they work well.

 

Truly, I can't remember. I was in line for over an hour. At one point, the engine was running, but I can't remember if I shut it off long enough for it to really cool down.

 

Sorry, my last response is a little confusing. I should've said "It was running most of the hour wait that I was in line and I can't remember if I shut it off, causing it to drop below operating temperature before it was inspected."

 

Wasn't confusing to me, just forgot to reply.
Generally, high NO/NOx will be attributed to high engine temps. A lean condition, or cooling system failure will be a good place to start. As I stated, I experienced high NO levels due to the overly efficient cooling on my ATV and once I got it nice and hot it got the NO level down (can't remember the
A P0420 could be caused by a lean condition, but you'd likely have other codes connected to it also. If you have or know someone who has an OBD scanner, check your fuel trim.

This is just MY experience, I am not a working mechanic.

 

Thanks Windsor! I appreciate your response. I have 9 more days to take it in for a free reinspection. I'll be sure to leave it running and maybe take my throttle pedal depressor with me to keep it idling somewhere between 1000 and 1500 rpm while I'm waiting. Thanks again!

 

Well guys, as you can see below, it failed again. The engine was good and hot. I set in line for about 20 minutes with it idling at 2000 rpm before it was pulled in for the test. The NO numbers actually got worse. I'm at wits end! I'm sure this truck runs better than most vehicles with half the miles or less, but for some reason it fails the NO test. I'm still begging for help. Hopefully, I'm not stuck with having to take it to the dealer. I'm sure they'll charge more than the truck is worth.

 

Still 90% sure it’s just under performing aftermarket cats. We deal with it all the time at work

 

Thanks empty_lord! The cats I have on now are the cheapest of the cheap so as usual I got what I paid for. What do you think of the Walker aftermarket cats? They are around $700 for the pair, but the OEM ones are over 4k for a pair if I’m lucky enough to find them. The OEM ones are not an option.

 

Walker is hit or miss. But on tundras they usually work out. magnaflow I personally have had the best luck with.

 

Thanks again empty_lord! So now it's up to me to make a decision and I'm open to all suggestions. Should I go with the Dynaflow cats @ $996 for the pair or take a chance on the Walker cats @ $724 for the pair?