Todays readings.I don't get it..

 

New cats need broken in. Did you drive it at all between new cat and retest? Some states have an amount of money that you can prove you spent trying to fix the problem and will pass you if you hit that. In Ga I think it's around $900.

 

New cat was installed by muffler shop AFTER emissions test today.Hoping new exh. manifold would fix and save me $$,but no..
Don't know of any programs here in liberalfornia,Iam sure I wouldn't Qualify.if one does exsist.
Tech said drive it 75-100 miles to seat catalytic performance.

 

I call BS on the "broken in" idea. (I'm pretty sure). Ideally your smog shop would be right across the street from the muffler shop. For HC for sure. We need help here Radi, Salad, Ken & all..High Nitrogen Oxide. Try it with the new cat in of course. It doesn't happen to have platinum plugs?

Nitrogen Oxide happens with high temp and pressure in the combustion cylinder. Maybe over 2,600* and around that pressure, 3,000 psi. I understand the Cat is there to burn off any HC, (unburnt fuel). Weather it lowers a "normal" NO reading, I can't say for sure. Is it "pinging", when you accelerate from 40 to 50 with your foot in it? Advanced timing, carbon deposits, or being a diesel could cause combustion that might produce NO. Or possibly a Platinum plug. (there is no timing adjustment)

 

Replaced plugs(champion coppers),O2 just before swing#2,post#10.
Seems like every time I replace something,readings get worse.
I disconnected + at battery when I R&R manifold.Wondering if this wiped EEC memory clean.Needs relearn again?It took at least 50 starts before I saw big improvements with 703s swap.
Anyother Suggestions?

 

Test #4 yesterday with new converter,another fail.Pulled 703s out today and installed OE injectors.
Don't know what else to do short of rebuilding 4.0.
Anybody got any advice?Must be a smog tech here somewhere..

 

are you getting the jeep nice and hot before testing?...it has to be HOT to work correctly...I drive up and down the freeway for a good 1/2 hour or so before testing...

 

Yes,plenty warm.20 min. freeway run,plus it idles while they do visual inspection.
Some techs say to test jeep 4.0 cool to get lower combustion temps?
I give up.She will be for sale if it doesn't pass with old injectors...

 

Finally passed today.Yippee!Replaced 703 injectors with OE squirters.Installed 180* stat.Water temp. was 170 ish during test.Changed oil,added 8 oz.purple snake oil with premium fuel.
Going to run a while with stock injectors just to get delta of performance and mpg.Got two years to build another 4.0....

 

Good job

 

Interesting. In theory the 703's should work AFTER it has warmed up. It will run rich on default pulse width in open loop. I believe others have passed with them. Might maybe there was a problem with a 703 or two? Glad you got it! I found that the 746 works really sweet. Was able to sell my 703's for enough to cover their cost, (and I gained at least one MPG).

Does the idle cycle, a couple times a minute?

 

Thinking the key was to lower combustion temps to bring NOx readings down.Swapping 195*>180* themostat did that.Test 2 years ago had 180 and it passed.
I will re-install 703 injectors later.Maybe even try 710s.No zip to acceleration and does not start as quick with OEs.Was getting 17 mpg highway with 703s.
Thanks for your help guys!