Affect of advanced timing on smog, caused Hc to rise.
 

I took my 92 Chevy Silverado K1500 for a smog check. First time passed all emissions, but timing was off & needed adjusting. HC was 86.
Had the timing adjusted took it back for retest & failed. HC was 133.
Adjusting timing will cause the HC to rise?
What can I do to fix it & pass smog?

Did the smog place check the timing? Why did you adjust it?


HC is unburnt fuel. More timing should lessen that. Did make sure the engine and the catalytic converters were FULLY up to temp before going for the smog check?

yah make sure that thing is hot AF before you get it tested. Don't shut it off while your waiting let it idle.

My first truck when I was 16 was a '92 ranger. Had to have that thing practically on fire to get it to pass. It had a rebuilt engine, but I'm pretty sure the cat just wasn't working well. Always tipped the smog guy for letting me tell him I was coming down and keeping the machine open for me so they could test it as soon as I showed up. :lol: