If the timing is advanced, will that cause a high HC reading? If I back the timing off am I likely to pass smog?

Add toluene? Xylene?

Thanks.

 

That would be rich fuel mixture.
High advance = high NOX

 

Remember you have to keep the timing within 3 degrees of stock to pass. They check your initial timing when you do the test. I believe its zero degrees for an LG4 and TBI, six degrees for a TPI, and ten degrees for a V6.

 

Thanks, guys.

 

Good luck

 

You guys were right, it was the NOx. Okay, I turned down the timing (I turned it down too far, so it didn't pass because it wasn't within the range). So, is there anything else I can do to drop the NOx, just so I can be on the safe side?

Thanks, again.

 

If the timing is on, the three things that effect nox are the cat, egr, and octane. If it is just a little high, and you are running 87 octane, 91 with some boost may bring it in line. If it is way too high, you may need a new cat. Egr will lower the nox, but I don't know if it even comes in during the smog test.

 

Russ is right on the money! Usually the EGR Pluged or Defective and or Cat bad. Good Luck!!!

Thomas
(800) 460-6789
www.houseofcamaro.com

 

Thanks, again!

 

Nobody even bothered to mention lean mixture, lazy O2 sensor, or low exhaust back pressure.

Advanced timing will cause HC to go up, but not as much as it affects NOx. A rich mixture mainly affects CO and a little HC, and Misfires cause high HC and low everything else.