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High NOX every year

30k~ on my fresh rebuild from 2016
4.6 stroker.


At my shop, one of the first things I would try is an induction service to clean any carbon off the pistons and valves. If you say it’s been running rich, you may have carbon deposits creating hot spots. Another thing to check is your CAT.
 
High nox would be running lean. Dump more fuel into it. Try a colder plug. High NOx means low CO and high CO is running rich.

There is a reason CARB puts their stamp of approval on the catalytic converters so I would almost guarantee the 49 state one is different. They have requirements in California and manufacturers don’t want to meet them. Probably because it costs too much money because they want more material in there to reduce emissions.
 
I cut my old fake flowmater off and the cat does not smell and I can see clearly through it.
I don't think it's shot.

O2 sensor. Change Bosch to NTK
New muffler.
Plugs.
Retest time.
 
Prior results for reference. Retest will happen Tuesday
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Sent from my Pixel 3 XL using Tapatalk
 
So.
What I learned today.

NTK o2 sensor. I can literally smell the difference. I wish I had a wideband to see. but smells better.

and my fake ebay flowmaster that cost half the real flowmaster.
Sounds 100% the same. no difference. LOL
 
Definitely going the right direction.

I’m doing plugs on mine. Mine shows high CO at high idle and it’s $20 for a new set of Champions.
 
CO went up.
NOx came down.

It’s still running a little lean so hopefully the next change works.

Interestingly your hydrocarbons came down.
 
Okay.
New plugs installed.
Timing at distributor checked. I am running little retarded 1-2 degrees like normal.
I kinda don't trust gas to have 91 octane with covid going on. and I can literally hear the stroker knocking/pinging at little at idle.
I mixed up some 110 octane~ and added a gallon to my almost full tank (normally I use this for my 80's honda motorcycle for long trips since it burns so much better/get +20mpg more). should bump up the octane a bit.


Gonna take her on a 30/1hour drive then go for smog today.
Will post results.
 
if you had the cat bolted on rather than welded, well then the cat can be removed and kept in great like new condition for a long time. a lesser cat can be installed for non test days. dont beat up your expensive cat off roading!
 
Looks like a good catalytic converter would have been the best option. 50k doesn't seem like much for a cat, but I'm sure it wasn't designed to be off roaded. Still....50,000 miles seams weak.
 
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