A.I.R. (Smog) Systems

[stovebolt]

Hi. I would like to solicit comments from those of you that drive your cars with a stock, fully functional smog system. I've read that upon deceleration there can be a popping noise and back-firing. Is this correct in all cases and are there any other adverse effects? It's hard to imagine that this was acceptable. Thanks for any input.

[JohnZ]

Hi. I would like to solicit comments from those of you that drive your cars with a stock, fully functional smog system. I've read that upon deceleration there can be a popping noise and back-firing. Is this correct in all cases and are there any other adverse effects? It's hard to imagine that this was acceptable. Thanks for any input.

"Popping" on decel/overrun is a classic symptom of a failed diaphragm in the diverter valve; when that diaphragm fails (and they all do after 20+ years), the valve defaults to full open, and air is pumped into the exhaust manifolds 100% of the time, causing the "popping" on overrun. The failed diaphragm also becomes a major vacuum leak through the signal hose from the carb to the diverter valve.

[KurtS]

The 67 system is much more problematic than the 68-9 system.