Here is a funny one.
I was dating a girl that needed a car really bad. I ended up getting her a Mercury Zephyr with a 200 CI I6 with 250,000 miles on it for $300.00. Car ran good.
Well, I took it to get emmission testing and it failed.
I took it into my place of employment to do a tune-up on it. I put new plugs, wires, cap, and rotor on it. Started it up and it ran OK, note I said "OK" and not good. I took it for a test drive when I got back to the shop, I heard a loud noise under the vehicle. It was a loud clanking/snaping/clicking sound.
I climb underneith it to get a better look at I notice the converter is cherry red.
I crossed the 5 and 6 wires. Oh crap!!! I quickly put them on wrong and start it up. Right away, it went from red to black.
Then engine then ran good. Nice and smooth.
I was sure I trashed the converter. I had almost an empyt tank, so I poured in 2 gallons of Isopropyl alcohol into the tank, drove to the station and put in a couple gallons of gas into it.
Took it to testing station and it passed with flying colors, better than new cars passed.
Mind yu, this was WITHOUT any polution control under the hood connected. Only the converter after it was cooked cherry red and alcohol in the tank.
It ran that was another 50,000 miles when the motormounts finally gave out and couldn't be fixed.
Tom