Well this seems very helpful however i hate that there are so many causes for misfire. My car threw 2 codes for cylinder 1 and 3, i erased them drove 2 days then it threw the same ones. I noticed the misfire a few times. only at low rpms though, and sometimes idle. I'm afraid to drive it to much like this it is my daily driver. I dont know enough about the previous owner but he was not old and wanted more power out of the car however had PDX Tuning do all the work for it. I could take her there but i cant afford it.first, hello and welcome to the site!
you mentioned misfire"s", are more than 1 cylinders misfiring? have you pulled a code? how much do you know about the vehicles service history or previous owner(s)? did it used to belong to an old fart who garage kept it, only drove it on weekends and was up to date on all of its service intervals or were they young, broke and stupid who tried racing everything but didnt know how to turn a wrench?
when diagnosing a car for a misfire it's important to know if its a single cylinder misfire, or if its multiple cylinders. constantly misfiring or intermittently. will it misfire at idle? under load? or WOT?
in order for a combustion in the cylinder to happen, you need Fuel, Ignition, Compression, and Air.
check for fuel pressure. if it was a lean misfire, it could be a fuel filter in need or replacing, or injectors need or cleaning or replacing.
check for spark. spark plugs could be needing a replacement or just could not be gapped properly. i've never seen an 02, but if its distributor type check for worn points inside the distributor. or some plug wiring that could be worn and grounding somewhere instead of leading to the spark plug. also be a good idea to check timing.
check for compression. you could have a leaking valve causing you to lose compression. or it could just simple need a valve adjustment. you could also have a burned exhaust valve causing pre-ignition.
check for air? lol quite simple. make sure your airfilter isnt clogged beyong belief causing a rich misfire.
thats just about all i can come up with. i'm sure others can or will elaborate more on my suggestions. happy hunting!
edit: well damn this thread just put my post to shame lol
oh well i tried