My CA Smog tests are performed at 15 and 25 MPH. Some say they have an idle test but I never had to do that. What is the best way to tune for smog?

Raise the coolant temp to 195*F? More/Less?

Advance / Retard Timing?

Balance the cylinder injector trims. Should be easy with an IR Thermometer.

Thanks.

 

No idea of your car but your crossover voltage can be set to something a bit leaner than 14.7:1.

Sorry I had a chart at one time that showed at what ratio co, nox, co2 is created but you can probably find it online. Generally, it is somewhere a bit leaner than stoich.

 

What about EGR settings?

Or changing tire sizes in the program?

 

I'm thinking about upgrading my cam to a 280XFI from Comp Cams (07-467-8). My HC Max is 83 @ 15 MPH and 48 @ 25 MPH on the dyno.

After the install, what can be done to help a car pass smog. People talk about Smog Tunes but nobody says what is being done to the tables. I did several searches to find small tidbits butt nothing more.

I've been reading up on drivability tunes but not specific to LT1s.

It is a 383 with an SLP Intake, Shorty Headers, cat back, and ported heads.

 

Hot combustion creates Nox in the below 2K RPM ranges That's why EGR adds exhaust at the lower RPM's to slow down combustion and "cool' the chamber. If Nox is high then you need to cool down the combustion process usually the 15-20 MPH (under 2K RPM) test checks for it . EGR is not needed ad at higher RPMs as the higher amount of air entering the combustion chamber tends to cool the combustion. High Co and Co2 are caused by rich or unburnt fuel AND the CAT not "re-burning" the Co/Co2 and changing it to soot. To pass Co/Co2 you need a good lean burn and it should get buy with a working CAT. High HC is usually always caused by a misfiring plug, burnt wire or bad Os'2 causing unburnt fuel to enter the exhaust. For Nox I would make sure EGR is cutting in at 900 to 2200 (stock setting), For Co2/Co timing should be close to stock if you don't have a cam, raise the coolant temp to stock setting to get a leaner combustion burn.Warm it up enough to make sure the CAT(s) are functioning.

 

Is a BLM of 132 sufficient for a lean burn? I can program the computer to hang there or adjust the O2 Rich/Lean Swing Threshold.