My 1995 4Runner Limited failed smog because of high NOX measurments. Results -
M1 15MPH 508 - MAX ; 1073 - ACTUAL
M2 25MPH 761 - MAX ; 914 - ACTUAL

The EGR is suspected and I am not sure that it is opening as it should. Until I read Mike D's explaination of what the EGR does in response to Michaelangelos question posted last November I didn't have a clue. I know where it is located but if I wanted to troubleshoot this part, or even changed it and related hoses where would I start? The tech did find that there was no vacuum when he disconnected the tuube going into the egr, but he said that it could be a number of things. I am trying to avoid paying the smog tech $90 to diagnose and then $65 to $95 for the part and Lord knows how much I'll get gouged for labor. Thank for any assitance.

My 88 4Runner failed the NOX too. The truck had been sitting for about 2 weeks prior to me driving to the testing station which was only about 3 minutes away. The testing people told me to drive it around for about an hour. I drove a half hour up the highway, turned around, drove back to the testing station. I then passed the test. You should try the same thing.

I've always heard that you should drive around a while before getting your car smog tested. I will have to try it. My truck had been sitting for a couple of weeks. Actually my starter went out on me back in December and because of the bad weather here I didn't have the chance to change it until this past Saturday. Afterward I drove it to the testing station which is probably about 5 miles away. Your solution could be the ticket. Thanks

I second the 'good long drive' as an effective manner of getting a pass on the exam. Also, it is very easy to check your EGR valve--apply vacuum to the valve and if the truck sputters and dies, the valve is fine. You can buy a vacuum for this sort of test for about 10-15 at any auto-parts store.

Also, check the EGR modulator. It is a little valve/filter that costs about $35 and could be the source of your issues. It was the source of mine. I went from a high NOX to ultra-low emissions. Good stuff.

mike v.