SMof fail in CA, High Nox again at 25 mph

So i pass everything with flying colors. Except Nox at 25 mph, its like 1100ppm when it should be below 600.

I have sealed 4 exhaust leaks, new large cat, new 02, new FPR, new EGR, new cap and rotor, new air filter, sea foamed it, acetone , HEET and injector cleaner in the tank, and new colder plugs.

So for the High combustion temps, I need it to run cooler and richer basically, any ideas on how to do this?

I was thinking to get it to run cooler and richer of pulling the Tstat out temporarily (180* right now) and also putting in a set of plugs 2 heat ranges colder and take out the one heat range colder plugs) , continue to look for more exhaust leaks (POS pacesetter header might have to come out altogether if I cant fix em) and any intake leaks or vacuum leaks. Also, I need to verify the new EGR is functioning properly.

I am thinking anything to make it runner cooler, richer, and increase back pressure as well due to the headers flowing too well, and lowering engine temps.


Does a hotter cat converter after it is warmed up help NOX at all?

Does a super hot cat converter only help with CO and HC? OR does it also help with NOX? Trying to figure if I should take it in cold or hot tomorrow morning for test number 3 after more work on the thing.

There is a lot of good information in this thread:

http://www.naxja.org/forum/showthread.php?t=1083101

And this one:

http://www.naxja.org/forum/showthread.php?t=1113734

Yep already both of those and maybe 100 other threads.

Does anyone know if the cat needs to be hot to help reduce NOX ? Or just CO and HC?

The damn thing runs so good and has so much power for being so old and beat up that I am surprised by the HIGH NOX. perhaps I have more than 4 exhaust leaks. Ill keep looking. Ill try it cold and hot tomorrow for testing , maybe.

Good luck!

fwiw, i put about 200 miles on my new cat before i smogged it.
i did the official break-in right after installing it. ran it at idle for a few minutes, then held it @ 2000rpm for about 10 min straight, then idled for a few more minutes. after that i shut it down and let it cool completely cold.
over the next week, i put around 200 miles on it, then took it to get smogged.
it was about a 15-20 min drive across town after being dead cold overnight, he put it on the rollers right after i pulled up. i know the cat was nowhere near as hot as it could have been.

i'm thinking you have other exhaust leak(s), or something is causing it to go lean under a higher load maybe? clogged injectors....map sensor issue...?

Yes at this point if it doesn't pass tomorrow morning ill be putting some serious miles on the thing. I am going to search for more exhaust leaks and intake leaks tonight as well as throw some even colder plugs at it, and some higher octane additive, among testing the MAP and o2 and egr.

I am also thinking clogged injectors as a maybe and if it doesn't pass this time . I am thinking in my gut that its the pacesetter header leaking at the intake/exhasuit manifold to head connections.

ill try to put another 70 miles on it tonight as well.

Crap!

I was working on a friend's '89 Xj, couldn't believe the 3-year-old CAT needed replaced. I drove an hour-and-some to Flores' house, where he hooked up his Snapon Scanner.After watching the run-time stats, he determined the CTS was out of calibration. The ECU never went into closed loop mode.

Without busting out the RENIX manual, and running some diagnostics, I'm not so sure what that 180* thermostat is doing for you.

good call. I have a MT2500 coming in the mail today. Ill see if I can diagnose something else like a bad CTS potentially.

Hypoid said:

The ECU never went into closed loop mode.

Click to expand...

I would have never guessed the problem, EFlores save me a lot of frustration! :thumbup:

Fixed it:
Had 2 more exhaust leaks that I found and a slight intake leak. Also for good measure I threw in a second heat range colder plug in, and one bottle of HEET , and Lucas octane booster. I also cleaned all the sensor connections, cleaned the battery terminals (better connection), I left the positive terminal off overnight, and aired up the tires from 25 to 35 PSI, and took it in cold and left the Efan on. It dropped NOX from 1100 to 11ppm at the 25 MPH test.

ah, great success! (borat voice)
:thumbup:

Sweet!

That is the first step; now to see what the ECU sees.