I'm out of ideas. She runs strong, no smoke, doesn't burn oil, no codes, high miles though 229k. New o2 sensor, ngk zfr6 plugs, ngk wires, thermostat etc. Cat is a couple years old. HC and CO are great. I can see the EGR working. I tried a gallon of dentatured alcohol with a few gallons of gas during a pretest and it was much worse, HC was high but NOx went to gross polluter. Before NOx was at 900ppm now it was at 2000.

It does look like someone welded the caps in on the EGR rail, not sure if thats how they're supposed to look. Saw some youtube videos of guys having to drill the caps off and brush the intake out. But I've never had an EGR code either. Thanks for any help.

 

Get the alcohol out of the car, put in 1/8 tank 91 octane and 1/8 tank e85 ethanol, itll pass everytime...

 

once it passes, get the ethanol out of the car, I heard it does wonders for rubber hoses

 

If sparkside everything is newd (cap&rotor?) then

Check timing, adjust valves, clean fitv/egr/iacv/injectors, change filters and warm the cat really well before test

 

1) ignore everything johnnybgood said
2) ignore everything johnnybgood said
3) If HC and CO are good, and only NOx is high, that means one or more of the following: 1) you have the wrong fuel in the tank. You NEED to use premium gas at all times. NEVER use anything lower than 91 octane. 2) the egr is clogged. the caps on the manifold are welded from the factory. that's why people have to drill them out to clean them when they clog up. You may end up having to do this. 3) ignition timing is too advanced. you need to get a timing light on it and check the distributor adjustment the correct way. yes there is an actual procedure for this, you can not just attach the light and check it. there is a series of things you need to do in order for the ecu to enter the right mode for checking timing. 4) valve lash adjustment is out of spec. do a valve lash adjustment no matter what, it almost definitely needs it if you haven't done it lately. for future reference, it's supposed to be done every 20k miles.

High NOx with normal HC and CO means the combustion temp is too high. This is caused from low quality and/or low octane gas, too much timing, or egr not working right.

 

If you knew what you have to do to pass smog in California you could tell me to shut up, all I know is my 95 Mercedes s320 had the same trouble and that was the only thing that would make it pass. it is proven and I have the paper work to prove it, if you would like to see it.

 

if you have to do some tricks to pass your engine is not working properly

 

Ignition system is all new, fresh chevron 91. Pretty sure the EGR ports are clogged then. Going to retire vehicle to the state for 1-1.5k. Thanks for the help guys!

 

Cleaning the egr ports is simple, retiring the car is flat out lazy.