420A In desperate need of help solving misfire.

[EritHorn7]

Hello all! Im new to the forum and to DSM! I recently bought a 1998 Eclipse GS. Has the 420a N/A motor and when I bought it it had a misfire. I figured some of the usual stuff, plugs, wires etc. But I've done plugs, wires, distributor, ran some seafoam through it and no luck. Misfire goes away at about 2800rpm and CEL goes off. I've been told everything from valve cover gasket to rod knock. I'm newish to cars but very new to dsm. Looking for any help. Attached a pic of where it sounds like it's coming from. Me personally I feel like it's a sticking or bent valve but need help diagnosing.

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[Bam_evo]

Connect an OB2 connecter and see what code pops up? I’m no professional mechanic but you seemed to diagnose well and your finger is right over a cylinder head.. maybe take into shop.

 

[EritHorn7]

I did. Code was p303

 

[Bam_evo]

What spark plugs you using?

 

[pauleyman]

Check all the wiring, coil pack, plug etc on cylinder 3. I would check compression and leakdown on at least that cylinder also. Look closely on that coil for cracks.

 

[1990TSIAWDTALON]

I fully agree with Paul, 0303 is a #3 misfire code for sure. Double check that wire and plug.
Thanks Paul!

 

[dustyboner]

you could also pull the valve cover and check to see if the noise is coming from a bad rocker or lifter.

 

[Sleepy2L]

Was this ever solved? My 99 GS is doing something similar

 

[BLACK'98DSM]

Was this ever solved? My 99 GS is doing something similar

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