Misfire help!

swaiteswaite New Wagonist
in Engine & Drivetrain
Number two cylinder doesn't fire at all. Spark is getting to the plug, however I'm not sure if the plug itself is sparking. Any ideas before I go to Autozone tomorrow to pick up new plugs, compression tester, and oxygen sensor?
I'm also a little worried about damage from continuing to drive it like this. How much damage can be done to the engine itself?

Comments

  • evol911evol911 familEE
    Sometimes oil leaks down from the seals around the top of the spark plug tube, the oil will accumalate and foul the plug (Has happened to me a couple of times, made my CRX sound like a Harley). Could be the reason for no spark at the plug. Could be the reason for the fouled O2 if its flooding so to say the #2 and dumping that gas into the exhaust. As for damage, #1,3 and 4 have to pick up the slack for a dead #2 so it probably is putting some extra stress so I wouldn't recommend driving it.
  • bam-bambam-bam Council Member
    The other potential cause of a misfire is no compression. Broken rings/lands, stuck/burnt/broken valves, head gasket? A compression test is the BEST indicator of engine health.


    Cross the spark plug off your list by swapping from another cylinder. You say it's getting spark to the plug, so the plug itself is the last link.
  • swaiteswaite New Wagonist
    Number 2 cylinder almost no compression. Everything else good. Oil deposits found on spark plug. What now?
  • wagodizzlewagodizzle Council Member and EDM expert
    time to either:
    a,) rebuild engine
    b,) replace engine
  • bam-bambam-bam Council Member
    swaite wrote:
    Number 2 cylinder almost no compression. Everything else good. Oil deposits found on spark plug. What now?

    Squirt a few cc's of engine oil in the plug hole, 3 or 4 pumps from a oil squirt cup. Repeat the compression test on that cylinder. If compression improves noticeably, it's piston/rings. If there's no difference, your problem is valves/head/gasket. This works because the oil will temporarily seal around the piston.

    My bet is the problem is in the top end. It's not common to see just one dead hole from lower end problems-it can happen, it just doesn't as often.
  • swaiteswaite New Wagonist
    bam-bam wrote:
    swaite wrote:
    Number 2 cylinder almost no compression. Everything else good. Oil deposits found on spark plug. What now?

    Squirt a few cc's of engine oil in the plug hole, 3 or 4 pumps from a oil squirt cup. Repeat the compression test on that cylinder. If compression improves noticeably, it's piston/rings. If there's no difference, your problem is valves/head/gasket. This works because the oil will temporarily seal around the piston.

    My bet is the problem is in the top end. It's not common to see just one dead hole from lower end problems-it can happen, it just doesn't as often.

    Compression increased so about 30. Soo looks like it's time for a rebuild. Or swap?
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