madbarry023

I just recently had my check engine light come on. upon seeing this i had the code read. The code was a misfire in cylinder 3. I pulled and replaced the plug replaced the wire and replaced the cap and rotor. The engine still idled rough and the light stayed on. Suspecting it was a vacuum leak i sprayed vacuum hoses and fittings will starter fluid to check for any leaks. No luck there so I'm stumped. If theres any ideas out there im game to try them.

Blue Bowtie

Welcome Aboard!

the #3 plug is not an easy exchange on a typical Blazer/Jimmy, with the steering shaft in the way.

Since you're replaced the plug, wire, rotor, and cap, you've nearly eliminated teh ignition system. It's time to start checking the other possibilities, liek fuel delivery to that cylinder, and compression in that cylinder. Since actually testing fuel delivery is not easy, it would be adviseable to check cylinder leakage or perform a cranking compression test to determine if there is a mechanical problem. If that passes (less than 15% leakage, or less than 10% variation in cranking compression between cylinders) you may have to remove the upper plenum and investigate the injection system.

riptide44

do the 2002's have one coil per cylinder ? other than that check the injector on that cylinder either sticking or shorting out