I have fought the cat efficiency codes (P0420 and P0430) for nearly 4 years now with my 94106's. Inspection the past few years has been hard and I was terrified this year. I failed again and the codes kept coming back. With my manifolds going out, I did not want to do my exhaust as I had planned. So I decided that if I could get the codes gone, I would do the Dynatech Catted headers kit in a year or so since I'll have a daily later this year.

I decided to try the old non fouler trick (or Gotts mod as people call it on here). Drilling out those suckers sucked and I had a hard time. I had read on a Corvette forum that one guy cut the shroud off his O2 sensor and it fit into the non fouler. After struggling with the drilling I grabbed a small copper pipe cutter. It's the type that you clamp around and twist it until it cuts the piece off. I did this and the sensor popped in. Low and behold... the codes didn't come back after a drive cycle and I got my sticker. I am not going to take credit for this as the guy that did it deserves the nod. But this makes the trick so much easier. You still stack the two non foulers, but it appears once that shroud is removed from the tip, it would slide right in. I was so relieved I passed I could not stop smiling the whole time driving. I had been stressed about it for weeks.

Here's his write up:

http://forums.corvetteforum.com/c5-t...ot-needed.html

This is the tool type I used:

 

Nice work again John, for the research and the verification

 

No problem Darren I'll keep checking for codes, so far so good. This may turn out to be a simpler method. That drilling isn't easy.

 

Still going strong with no light. Around 300 miles right now. I had previously gone 100, then rest it when I loaded the Predator to my truck. So it reset the P1000. Total of 400 or so miles now.

 

I have been dealing with the P0430 code for almost 4 yeas now...am considering trying this mod...My truck passed Califonia Smog (I live in an enhanced smog check area) back in August despite the persistent code...seems worse in the winter as it comes on about every 100 miles, and summer 300-700 miles...it would seem that if the cat was truly bad it wouldn't pass smog?

My only option here in California is the OEM Ford Cat at $ 2300, as the CARB has banned most aftermarket catalytic converters for the 2005 F150 5.4 4x4...
I am also thinking about changing the fuel injectors on that bank to see if that is the problem...

 

I'd have the cat tested. Be careful doing this. It IS illegal... my inspection has emissions but they don't look under my truck. They usually drool all over it and the Guy calls everyone over too look at it haha. I think magnaflow makes CARB cats for our trucks. Do you have an early '05 with 4 or a late '05 with 2 16" cats?

 

good find John....

 

Interesting approach. Drilling isnt that bad. I did one for a coworker. Took about 2 min to drill it out.

 

Hey Truckguy!

My 05 is a 06/05 Kansas City Plant...never measured the cats... I do have 2/side
Just checked the CARB Database...there are Cats approved for the 4.6 but not the 5.4...trust me, if there were aftermarket available I would have changed it...I am having a hard time justifying a $ 2400 cat on a truck that is worth $8k at the most...

Have considered going to Nevada and buying 49 state cats for about $200 each...

 

Yeah that's rough man, I hope you are able to find something. If they don't look under your truck, this may be a good route to go

 

They look everywhere in California - they even look for CARB stickers on anything that's not stock. They do visual, OBD2, and sniffer on a dyno, and it's all computerized with the computers talking direct to the state - almost impossible to cheat.

 

Maybe I should go to Midas...my idle could be a bit ruff...

Just did a trip to Lake Tahoe over the weekend...about 350 miles from 125 fee above sea level to 6700 feet above sea level...no codes...

 

I'm gonna have to say this is probably a safe way to go. Still no codes

 

Got inspected again today. A solid 12k miles or so and still no codes since I did this.

 

I did the Gotts mod almost 2k miles ago...no codes...just did a 400 mile trip yesterday...200 of it towing a cargo trailer into the Yosemite area...

I had to use a tapered and regular non fouler, then stack the washers...but its holding good...