Doc Brnard

xXWhiteXjJeepXx:

I caught your thread because I was having the exact same problem and almost identical #'s with my 1991 4.0l Chero.

1st attempt(2 days ago):
15mph
O2: 0.2 CO2: 14.6
HC (86-26) -20ppm CO (.73-.10) -.20ppm NO (711-254) 913

25mph
O2: 0.1 CO2: 14.7
HC (103-22) -12ppm CO (.93-.11) -.18ppm NO (613-173) 765

Everyone said "It's the O2 sensor, change it and you are gold." Okay, did that, and took it right back after driving around for 30 min.

2nd attempt (yesterday):
15mph
O2: 0.3 CO2: 14.3
HC (86-26) -98ppm CO (.73-.10) -.60ppm NO (711-254) 1790

25mph
O2: 0.0 CO2: 14.9
HC (103-22) -11ppm CO (.93-.11) -.19ppm NO (613-173) 722

So I was WTF?????? My numbers got worse! So bit the bullet and took a chance. I replaced the Cat, and drove it around for another 45 min.

3rd attempt (today):
15mph
O2: 0.0 CO2: 15.1
HC (86-26) -35ppm CO (.73-.10) -.02ppm NO (711-254) 59 !!!!!

25mph
O2: 0.0 CO2: 15.1
HC (103-22) -16ppm CO (.93-.11) -.01ppm NO (613-173) 4 !!!!!!!!

PASSSSSSSS!

Just thought I would share this experience, and maybe help someone else dealing with the same problem.

xXWhiteXjJeepXx

I actually just smogged my jeep today. I changed the egr valve and transducer. Put a new magnaflow cat on it, New oxygen sensor, sea foamed the engine, and for the past couple months ive been running lucas fuel injector and top end cleaner about every other tank. Emissions went all the way down to 1 at 15 mph and 2 at 25 mph. all my other scores went down alot also but it passed with flying colors. i also drilled 2 little holes at the top of the exhaust rite after the muffler which prolly helped with everything as well. just wanted to let u guys know how it turned out

xXWhiteXjJeepXx

Wow doc, ur numbers were very close. Seems to be the catalytic convertors on these old jeeps. I guess overall i would say that helped the most

Fredzo

New Cat tomorrow before I take it in for a pre-test. I notice that you also live in Californicate.

Thanx!

Fredzo

Does anyone know the p/n of the Autozone Clamp-on CAT? I'm trying to go cheap, as this will be my daughter's D'D.