1994 B3000 3.0 High NO levels, smog fail

[kylep123]

My truck failed smog today, I had recently replaced the heads with rebuilds due to a blown head gasket. It barely passed two years ago, but has been running much better since I did the head job. All levels were comfortably below the max levels other than the NO levels Max are 522 @15mph and 542 @25mph, my truck read 1365 @15mph and 1446 @25mph. I was told that it may have to do with the EGR system, any tips or pointers would be greatly appreciated.

Thanks,

Kyle

 

[adsm08]

The EGR system is designed to reduce NOx. The cats are there to eliminate it.

First thing I would do is put some vacuum to the EGR valve while the engine is idling. If the valve works it will stall the engine.

If the EGR valve works I'd look into a new cat. Also, the cats work best when they are up to temp, about 400*. Don't drop the truck off, go drive around for 30 minutes and then go to the inspection station and wait for the inspection.