i heard it passes easier with stock tires if you dont have them on then see if you can get ahold of a couple, a freind of mine was asking for just 2 back ones to take to the smog shop

 

Combustion temp is a little hot at idle, causing an increase in NOx.

Do a smoke test in the intake - even 1 cylinder running a bit lean will drive up the NOx at idle. At above idle the vacuum leak has less effect.

Engine off - Disconnect a vacumm hose on the intake manifold - blow cirarette smoke down tne hose into the intake manifold. Fix where it comes out.

Make sure it's got a tankfull of fresh gas before testing.
And - add a 1/2 pint of DENATURED ALCOHOL just before you take it in. The alcohol will lower combustion temps slightly - and lower HC.

Denatured alcohol is available at paint stores - it's used as a cleaning solvent - $1. Same stuff as sold to pass smog for $12.

 

I have some 23" tall tires on my trailer that would work, same lug pattern.

It will up my rpm's at the same speed, theoretically make me pass!

 

I like this idea. Especially the smoke test.

 

well I got it to pass!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

It wasnt the o2 sensors, or the cat, or the MAF!!!

I went through all the usually **** people tell you to try and nothing worked.

What actually worked was a 180* thermostat and running colder Champion RC9YC spark plugs!

This works assuming you have good sensors and no vacuum leaks!

Hope this helps somebody in the future!