I had about a 1/4 tank of 12+ month old gas and only started the car every few months during that time. Couple of weeks ago i started it and drove it around the neighborhood. The O2 sensor light on my Edelbrock Pro Flo system constantly showed a lean condition (red light). I increased the fuel amount by a few percentage points but didnt help. Before the car sat, it was tuned well.

The other day I went out and filled the remainder of the tank with fresh 91 octane fuel and drove it around the neighborhood a couple of times for about 20min each time. The light would inconsistently flash green around 1700rpms but go back to red anything above that. I don't hear any pinging and its not running hotter that it normally would (around 190*)

Could the old gas be causing the sensor to read lean or do I have a different issue? I plan on taking it for a dyno tune, but want to make sure that if I have bad gasoline it doesn't affect the tune they will load.

Thanks
Mike

If the gas is old, could cause a missfire will will read lean...would probably make the ecu go nuts trying to compensate.

Things like this are probably why Doug F tells me to turn the learn function off after a while!!!

I put some IsoHEET in it to control any condensation that developed after sitting there and will keep driving it to flush out the gas.

Thanks.

Things like this are probably why Doug F tells me to turn the learn function off after a while!!!

+1 -- this is exactly why I turned mine off closed-loop after I got my fuel table well-dialed in.

-Dave