Car: 1998 Formula

Miles:130k+

Problem: random miss on #5 Cyl.

Stuff Ive already done to try and fix/track down the problem: Changed the plugs, wires, coil pack. Swapped #5 Coil Pack with #3 to see if it might have been a bad/new coil pack, Swapped injectors to see if it might have been the #5 injector going bad.

Stuff I havent done yet: Was told by a friend the other day to do a compression check.

Everytime I stick the computer to it its always on #5 Cyl. Im fresh outta ideas other than pulling the motor and just redoing everything...

Possibly a valve going bad?? Whats yalls take on this?

 

What does the number 5 plug look like, do you feel this misfire or is throwing the code only?

 

the next thing i would do is to pop the valve covers off and have a look at the valve springs

 

as elias stated i would pop off the valve cover i have seen where the rocker arm bolt has been pulled out completely,treads and all(loves aluminum). if everything turns out normal there i would do a compression test,may have a burnt valve.

 

like these guys said easiest thing would be to do a compression test and check the rocker and valve spring.

 

What bothers me is the "random" part of this - if it were a burnt valve or bad rings it would be a solid miss.

 

That's what I'm thinking, broken spring

 

Its definately a miss regardless its solid or random. If your driving on flat land round 60mph you really dont feel it miss.. but if your under load goin up hill or just sittin still in park you'll feel it miss really hard at like 5-20 second intervals... Now I just gotta find me a compression tester and pop off that valve cover... ugh looks like my holiday week just went to ****

 

swap coil packs from one side of engine to the other, could be a bad pack harness...been there done that