Hey gang,
So I have a '94 22RE truck with a mild Crower cam in it. It's been failing the smog test. NOX are fine, it's just a little high in the hydrocarbons. EGR and cat are working, O2 sensor is new. Cap, rotors, plugs, oil are all fresh. Even put in a gallon of that Flex Fuel.

We're thinking the overlap in the cam is juuuuuust enough to put it over. I've heard of people loosening up their valves to essentially make it a smaller cam and squeaking through the test. Anyone here ever tried that? Also, what would be a guess on how loose to run them? I'm sure it will sound like hell but I just need to pass the test without damaging anything.

Thanks!!

 

To be honest I've never heard of loosening the valves having a positive affect on the smog numbers. If anything you will just throw off your efficiency and make your HC go up. If you wanted to cheat maybe trying to clamp down a fuel line to drop the fuel pressure might work to put less fuel into the motor, but that might raise your NOX if you go too lean. You could also try turning down your MAF to see if that could lean out your motor a bit, but again too lean will raise your NOX through the roof. What state are you in?

 

I dont know if I would mess with the valves. If your valves are good I wouldnt touch them. You might check the pcv valve. I have run the lc efi cam for years and have never failed. Its been high on the test but never over.

 

Yeah, we tried messing with the MAF but it would put the NOX over the limit when we got it lean enough to get the HC down under the limit. I'm in California, btw. (I didn't realize my location wasn't showing up. Fixed that.)

 

Yeah, I mean my is just barely over. At the 25mph test it passes but the 15MPH test it just doesn't quite make it.

 

Try some "seafoam". Follow the directions on the can for vacuum line cleaning and throw a can in the tank before you head to retest... If that don't work pull the sniffer halfway out of the tailpipe while the inspector is not looking!

 

try a gallon of denatured alcohol to a full tank of gas. it will drop your hc but will raise your nox. because alcohol has 1 carbon atom and gas has 2 carbon atoms. there for leaning up the mix.
also try to advance your timing to the max the state allows. i believe you have a buffer of 2 degrees either way from the emissions lable. having the timing advanced will allow a more complete burn of fuel. this can also raise nox. so be sure to pre test the truck to see where your at on the changes. doing too much will push you too far.

Also be sure to have your cat piping hot. i usually drive on the freeway prior to smogging any vehicle and when waiting for the smog i let hold the engine at 1500rpm to keep it hot. a hot cat is a happy cat.