BMJ

Son's 3vze failed the Low speed emissions HC(PPM), standard is 220 and his reading was 449,
Yet the high speed HC(PPM) standard 220 and tested 24 so passed.
What can be the culprit here? Air filter is new, runs well otherwise. Any input would be appreciated. Never has had the O2 sensor replaced or cat and has about 212k on the car. Passed last year?

Thanks
BJ

theAuthority

Let me know if you can figure out what I did here.

Team420

If you got 212k, and have never changed the o2...you likely need a new one... the cat MIGHT need replaced as well to pass emissions.

sb5walker

My veezy did exactly the same thing - very low emissions at higher revs but too rich at idle. The fault was the throttle position sensor - specifically, the IDL and E2 terminals had no continuity when throttle was closed. Adjusting didn't help. I replaced it, and it started idling smoothly and it aced the emissions test.

It's easy to test with an ohmmeter. If no IDL/E2 continuity at idle, try adjusting per fsm specs. If you can't get the terminals to make contact, replace. 1sttoyotaparts is cheapest for a dealer part, or try rockauto.com or local parts store for an aftermarket.

http://personal.utulsa.edu/~nathan-b...93throttle.pdf

Since you have good HC numbers at higher revs, your O2 sensor is probably fine, though I think it's unlikely to be the original one.