I have a 1991 z28 with a 305 tpi. My o2 sensor went out again. I replaced it but the car has a rough idle to it. Also when i use the a/c i smell fuel in the car itself. Any ideas. Is there any way to bypass the charcoal canister or the smug pumps at all. Any advice will be grateful. Thanks Bryan

You could just unplug the hose going from the canister to the intake and see if it still idles rough. As far as the smog pump, it shouldnt be operational at idle. Just unplug the hoses that go from the air pump diverter to the exhaust manifolds (at the diverter) and see if there's air being pumped into them.

I've been diagnosing a rough idle myself and there's a lot of possibilities. Without a scanner or data logging, it can be very hard to figure out. You just have to start testing component after component.

If your a/c smells like fuel, Id very thoroughly look for a fuel leak in the engine compartment first (check and double check everyplace fuel could run under there, car fires probably arent good times). If youre sure there isn't one, you probably have a pretty mean rich condition going on.

Any trouble codes?

It threw an O2 sensor running rich?

What do you mean it went out again, how long?

O2 sensors don't go bad for the most part unless there is an internal short [rare] or they get dirty.

They should amost last forever.