Hello Scotty I am Cassidy, I have a 1990 s10 blazer with a 4.3 Tbi engine, recently was doing some work on my truck and when I first dived in noticed one spark plug wire was off the spark plug on the driver side rear cylinder. When I plugged it back in and had the car running I noticed a noise. I am wondering if the unburnt fuel is going to run down past the piston rings or damage the valves guides or pushrods and cause damage or if it all just gets sucked out the exhaust and has just maybe ruined my cat? It was running like that for probably about 500 miles.
You could get a compression test to find out for sure. How is it running now? If you suspect fuel dilution of the oil, change the oil and filter NOW!
what kind of noise? I don't know how you notice a noise now, but you didn't notice a missing V6 cylinder for 500 miles.
Pull out your dipstick and smell it. Does it smell like gasoline?
It was running with a busted fan clutch and ac compressor it was making lots of noise.
would have been shaking too