I had my 88 smogged today and failed NOx limit. I then checked my printout from January '09 and found that my truck is slightly better this time, but the max allowed has dropped from 1058ppm to 740ppm. Anyone in Yotatech land noticed this (in CA of course)? Why did they lower it and by so much? Thanks, Walt

 

Well, if anyone's interested, I called the smog tech today to ask about the lower max on NOx. He says it was lowered and they will keep lowering it.

I looked through the stuff I rec'd from the previous (original) owner and his smog check in '02 showed 91ppm for NOx. '04 smog check showed over 1000 ppm. I plan to try a new O2 sensor and look for vacuum leaks.

 

High nox usually ties into= catalytic converter, egr, and cooling system.
Yesterday a guy passed with using e85 in his tank. There's a thread

 

here you go
https://www.yotatech.com/forums/f116...c-3vze-223919/

 

just put 20% methanol and run a pre test. You'll find the nox goes down quite a bit, if not enough at least it was a pre test. Go home, put more methanol in there and run another pre test. Repeat until it passes.

 

The issue I heard was that in States like California and Arizona old cars don't die of rust like they do on the other end of the country. Old cars have had less strict measurments to pass. So they started making it more strict to help the "planet", in the hope these "gross Polluters" would either get cleaned up or pulled off the road..

So who makes more bad air, Cars or Industry?

 

My Cat is relatively new though. I'm thinking about getting a Denso O2 sensor. Need to rule out vacuum leaks too.

 

Just got denso o2 sensor shipped for like 55-60$ from rockauto.com

 

Make sure your egr is working, and get a spray bottle with soapy water and spray it over the vac lines and see if there is a leak.