CA Smog-High NO

[Bronco]

I changed the oil and took it in for an inspection this morning and here are the numbers.

This is the third time I’ve ever had to smog it and the first time it has failed. I’ve done quite a bit of reading about smog with the search. It sounds like the root of my problem may be the EGR system. My truck does have a substantial blow-by problem. Are these two thing related? There is no EGR valve that you can replace, right? I have been meaning to pull the valve cover off and give it a cleaning anyway. Do you guy who know about smog think this will take care of things. My vacuum hoses are all fairly new and in good shape, so I don’t think that’s the issue. All my readings are somewhat higher than average. Also I drive this thing to work only a mile and a half away, so it a lot of really short trips. Could come into play here? Anybody have a breakdown of what sensors are involved with the different readings?

 

[old_man]

Running too lean yields a high combustion chamber temp. That gives you high NO readings. Personally I would run a can of good injector and combustion chamber cleaner such as BG55K. The next most likely problem would be an O2 sensor.

 

[mattmankow]

Most likely cause is a bad cat-converter.

 

[Bronco]

Here's last time agine.

Here’s what I did this time. As you can see I just passed.

As a matter of fact I think the guy testing it helped me out. He was running it and a he jumped out and shut the thing off and then came and told me it didn’t look like it was going to pass but he thought it may if he gave it a few minutes. I guess if he let it go the full 3 min it calls it in to the state but if you shut it off early it doesn’t tell them. So he let it idle while we shot the bull of a few and then he ran it agine. Between the fail and this I replaced the plugs and the air filter as well as the O2 sensor and I also cleaned out the valve cover cause it needed it anyway. It looks like I will need a new cat for next time. Another thing that is different from last time is the RPM. I guess the operator has some discretion on exactly what RPM to run it at. I’m not sure if he had it in a different gear or if the MPH is only an approximate number but something was different there. Just for the public knowledge the tech also told me that if the cat is working right the %O2 should be 0.