UPDATE:

I removed the CAI intake and put the stock one back on. The CEL came back on after about 100 miles this time. So, I'm left with one final thing, the HFC. I will take your recommendation about the gaskets and will inspect them before making the change.
This is driving me crazy!

 

UPDATE:

Up to this point, i had removed my plenum spacer, CAI and now the HFC. The gaskets were all in great condition and I observed no leaks whatsoever.

The stock cats have been on for over 250 miles now and no CEL! After jogging my memory once more, I remembered that the CEL did come on after the HFC were installed on my car before all the rest of the mods. The car drives great and my observed mpg is ~23.8 while before removing the HFC, it hovered around 21.0 mpg. I will be reinstalling the spacer and intake in the next few days.

To Onagao:

In your sig it says that you have ART pipes. Im assuming those are tp's? Try to remember when you first saw the code. If I were you, I would replace the tp's with the stock cats. I'm beginning to think that its the excess vibration that could be causing the code.

Thanks, hope this helps.
I will post another update after a few hundred more miles.

-Regul8or

 

I'm contemplating doing that. I doubt that's the source, but it always could be. The ART Pipes are helmholtz resonance-tuned straight pipes, so they should actually be eliminating unwanted vibrations as opposed to causing them. Granted, this problem showed up around the time I installed them - I've always assumed that since nobody else with these is having this problem that it wasn't the cause.

 

UPDATE:

Since my last post, I have removed the HFC, installed the stock ones and put the spacer and intake back on. I have driven around 3000 miles and no CEL!

The HFC were the problem afterall. I would have loved to fix this problem, but after searching and searching, I found no solution.

Hope this helps anyone else out there with this issue.

-Regul8or

 

Very nice! Do you still have your HFCs? If so, did you inspect for any cracks in the welds or leaks along those lines? One mechanic I spoke with mentioned code-inducing cracks in the welds that he's seen flap open under certain conditions -only to fall back in place and look normal under most others.

 

I looked them over pretty well. No sign of cracks. The only thing was that the inner material used for filtering the exhaust gases was moving ever so slightly inside the HFC's. This was due to vibration I'm sure.

Car feels infinitely better now!

 

Well, I'm really happy for you. That's fantastic. I can only imagine the relief it must be.

So to clarify - you don't know exactly what the cause was, just that the replacement fixed it?

 

Dude put your stock cats back on and see if thats it? Everyone had either a leak or a crack in the catalyst, so what else could it be. Especially after the engine replacement.

 

Dude, I would be all over that if I still had them... I gave both my stock cats and my Stillen HFCs to my brother in New Mexico. So I've got nothing to put on there. Any ideas?

 

lol no.. have you had a good look at them? (ART's) Ask to borrow a member's locally for test purposes?

 

Sounds like this is a common problem from 350Z cars. I was told that my needed a air flow meter then an O2 sensor...after being only 3 yrs old...i doubt it was really the part that needed changing...

So the part was ordered after waiting for over a month for the part to arrive from Japan.. and then fitted by nissan...after 430km i am still having the same problem...

The same code is still showing... and the car definately feels sluggish when the engine light has come on the dash.. even though the code has been reset and taken back to nissan again...

Not sure what the hell is wrong with my 350Z... have anyone found a solution to this problem yet..?

If Nissan can't rectify this who can ?

 

Wu-Wutt,

what is a TP?

 

Wu-Wutt was referring to Test Pipes. (straight pipes in the cat section)

 

i have this code on my vortech , came on 100 miles after my tune. motor is fresh built with all extras, i do have used arts but havent noticed any cracks ect. also have tomei headers. this thing is driving me crazy. ive dropped 15k in this build and havent been able to ejoy the car for a day. now im gettin a high idle with the code, low boost, and my bank 1 is running super rich. i dont want to take my arts off after being tuned with them... any help would be amaizing. id pay what ever to just have this fixed!