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Truck's been running rich, gotta get rid of stock exhaust..

4914 Views 3 Replies 3 Participants Last post by  westracing01
So, one of my catalytic converters started going buh-bye on me a while ago, bank 1 Pre-cat. I could reset the code and the P0420 came back on some time eventually, sometimes took over a week of everyday driving. Well, my bad for driving with a bad cat, the o2 readings from having a bad cat causes the engine to run more rich than it should, more fuel than the engine needs. While's a while later on to present time I can now start to smell the fuel in my exhaust and the code pops up quicker than ever after a reset now...

Instead of running 3 hours to my closest trusted dealership, I'm wondering if giving myself some extra power, great sound, and peace of mind... would be a better idea, I figured I'd ask you guys for the best advice.

Since one of my pre-catalytic converters went bad and ran the engine rich, I'm perty sure that the other pre-cat has got to be on its' way out too, also, because the bank1 cat has been bad for a while, i'm perty sure its' already gunked up my secondary cat on bank1 also...

Do headers cancel the pre-cat? If so, I'm allover the idea of headers. Can I just put a single aftermarket catalytic converter on each bank instead of two..?

Boo, this exhaust crap is just too much...
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A Inefficient Cat Wont Make Your Truck Run Rich, But A Rich Running Truck Will Kill Your Cats. And As The Begin To Clog They Will Start Killing Power And Mileage. Youre Covered For 8/80 On Cats Are You Past 80k? Fix The Engine Issue Before You Start Replacing Cats. And Yes The Headers Will Delete The Cats, How Is Utah On State Inspections? With Headers You Will Always Have Cat Codes Since They Wont Be There Anymore. You Can Try Simulators, Or Downstrewam 02 Extenders To Move The 02's Out Of The Direct Exhaust Stream Which Make Them Think The Exhaust Is Still Being Cleaned. Or Get Uprev Tuning And Have The Codes Deleted
thanks BRUTAL

Yes, my truck has a rebuilt title though, Nissan's finding out if it'll still be covered under the 80k/8yr. I've put 11,000 since I've owned it, been a great, great, feels/drives like new truck.

Hmm, then I wonder why it could be running rich? Can a o2 sensor with a bad/no connection be the cause? Maybe a bad ground the the ignition system? It runs pretty dang great other than the fumy exhaust ... Driving 70 on the highway I get very close to 20mpg.. around 16/17 city. I've torn the whole front body components apart looking at the previous history damage of this truck. Looks as if NO wire harnesses have ever been touched, nor anything beyond the radiator. All I can see is that the front right wheel-well has taken a bit of a hit and been repaired very well, I got this truck super cheap, any problem's it's got i'm willing to figure out. There's a maintenance log that shows "thoroughbread nissan of Az" ... so it appears to be well maintained.
BRUTAL, I know the long tube headers will delete the cats, but the shorties don't. I looked at the NISMO instructions last night and they bolt to the front cats and retain the O2's and emissions equipment.
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