Low speed emission results (15mph)
------------------Standard-------Current reading
HC(PPM)------- 203------------152
CO (%)---------1.15-----------0.55
CO2 (%)------------------------13.6
O2 (%)--------------------------1.9
NOx (%)--------1577-----------2616

High speed emission results (25mph)
------------------Standard------Current reading
HC(PPM)--------197------------135
CO (%)----------1.27-----------0.52
CO2 (%)-------------------------13.8
O2 (%)---------------------------1.7
NOx (%)---------1440-----------2218


That was my first run since then ive replaced Plugs, wires, cap rotor, O2 Sensor, Ran Seafoam trough the motor and also tried retarding the timing. and results are always very similar to the first time i went in. Any ideas? Can my cat be bad even though all my other readings are good?

 

looks like the cat is pretty much dead.

 

Thanks for the info bro. Ive been searching here on threads related to nox and there are so many people that say cat dont have much effect on nox and so many that say it does

 

CAT. O2 is up and all the numbers are up.
And the cat has two parts. The front part is for HC & CO and the back half is for Nox.

You gross polluter you!

 

So you guys think a new cat will drop my nox readings to an acceptable range?

 

Not that I deal with emissions much but I thought high nox was due to lean mixture.It's kind of a trade off with low hydrocarbons.There are many oem techs on this board that deal with this a lot more than I do.

 

My 88si rex was worse than yours 3300ppm for nox. Replaced the cat and O2 and it brought it back to the average numbers on the test. Your numbers are almost like mine used to be.

A lean A/F mix does create more Nox because it burns hotter. If his numbers were at 10 -20ppm on HC then yes it would be a lean mixture. But his are not.

Your O2 numbers are up. That is why I say it's the Cat. Meow! Your O2 should be almost 0.0 or near that.

So yes it will. I got my stock replacement cat for $85 and paid a muff shop $30 to put it on.

And don't retard the timing you will start to raise the CO if you retard it to much.

 

Hey thanks a ton for all the helpful info bro