I've been having a random misfire condition lately with no cel's. It's happend twice so far and it felt EXACTLY like it was running on 3 cyl. This was at warm idle. When I started accelerating it gradually went away within a matter of 5-10 sec, not showing up until today again. Same thing happend today, went away gradually while accelerating, smooth idle, no problems afterwards. Apart from this I've been having slightly poor low end response with the 3k hesitation.

Checked plugs, odd results:

Cyl 1: Looks rich, carbon deposits, right above the tip area (metal) where it says 'Japan, etc' looks burnt.

Cyl 2: Normal, slightly/if-at-all lean, right above the tip area where it says 'Japan, etc' slightly burnt.

Cyl 3: Lean

Cyl 4: Lean

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Everything is stock/OEM

Within the last 8k miles (all oem):

Wires, plugs, rotor/cap, fuel filter, etc + half can of seafoam in gas tank.

 

Id guess you bent some valves. My buddy with a H22 had what sounded like a miss at idle and when cruising normal it sounded like he had a major exhaust leak. It was also sluggish in the lower rpm levels. Had no cels either . Did a compression test and it was 190 195 140 140 . SO we knew right away. Do a compress check and see what you got.

 

If I had bent valves, I don't see how the problem could be intermittent and go away in a matter of seconds.

 

well i had a similar problem for me and my plugs looked ok.. so i took it to a shop and they said all i needed was new plugs..

 

At what point are you pulling the plugs to check for rich/lean condition?

Can you get it to miss for an extended period of time? For instance if you hold a certain rpm/throttle position/gear then KILL the ignition and pull the plugs and see what they read. If you feel the engine missing/hesitating and then continue to drive it around and eventually park it THEN pull the plugs you will get a corrupted reading.

How many miles are on your engine? Could it just be a bad tank of gas? When's the last time you replaced the fuel filter? Ever had the injectors cleaned/flowed? Did you try to reset the ECU and let it relearn? Check the valve lash to make sure it is all the same. If you have loose lash it will change the lift and duration of that particular cam lobe in comparison to a tigher lash on another. How old is your ignition system? Worn rotor/cap/wires/plugs can cause missing too. Excessive carbon buildup can also be from burning oil. What's your compression for each cylinder? Is there a possibility that your valve seals are worn?

Pirate

 

so are you saying that you have changed plugs wires rotor cap and you STILL have the problem or so far the problem has not resurfaced.. usualy any type of missing is ignition related.. ususally, in rare cases an injector could be going bad and either flood one cylinder or inject no fuel at all.. but with it being so intermitent i would think its ignition..

like pirate said, try to find a condition that replicates it consistently and then use plugs to narrow down which cylinder it is.