I have a 2000 Honda civic ex, I'm getting codes for all four cylinders misfiring. I have new plugs, wire distributor cap and rotor. No improvement what so ever. What else can I check?
Clean your MAF, see what happens.
When was you last good injector cleaning? If what Tom stated doesn't work you might have them cleaned. I run a bottle of Techron with every other tank of fuel, the stuff they call fuel today need all the help it can get.
how many miles on the engine? May need plugs and coil packs if over 100k.
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