mystery misfire question

[shippy8907]

okay I started to have a misfire on cylinder 5 after letting my car set a few days without driving it. so i started with the basic stuff like swapping out the coil for a good one and swapping out an injector and also putting in a new plug. I still have the misfire! I know I am getting spark because i have hooked up the coil and plug and watched it give off a good spark. and I know I have fuel because I can hear the injector firing just like the others. So what could it be? the only thing I can think of is if there is something wrong with the valves. would that cause a misfire? im completely stumped on what to do next and I just want to get rid of the car now.

[evildky]

if the injector is firing and the plug is sparking the next potential issue is a physical one, a compression test and leakdown test will help you determine if ti's a head or block problem

[shippy8907]

thats what I was leaning towards too. I just wanted to make sure and get another opinion just to make sure there wasnt something obvious i was missing. I have a feeling that it is the valves causing it because it has had the misfire before and then would clear up after driving it for a few minutes, but now it wont come out of it. im going to do a compression test on it as soon as I can. are there any additives out there that would be good for trying to free a stuck valve?

[evildky]

if it's a valve issue it's likely not a sticking issue, the more likely issue is a cracked valve seat and that means pulling the head