Oxygen sensor
 

A mechanic told me that an oxygen sensor could cause a misfire in the number four cylinder. Is this true or is this false information?

Slash,

I am a Product Specialist with Walker Products, a manufacturer and worldwide distributor of oxygen sensors. An oxygen sensor cannot directly cause a misfire on a particular cylinder. What a malfunctioning oxygen sensor can do is contribute to an improper a/f ratio, which can cause drivability issues.

I would start by looking at your spark plugs and fuel injectors as the possible causes of your misfire.

Yeah i agree. Check your spider injector. I had installed an after market spider on my 4.3 and i had a wire on 1 of the injectors rub on the upper intake causeing a continues pulsing injector that caused the misfire. Good Luck