Thread: misfiring

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Took my headers off this afternoon to check all my plugs. Engine was misfiring. Only found one bad plug#8 coated with oil. Put new plug in, others looked great and still misfired. Put spark tester on plug wires and they all are firing ok. Whats next? Pull valve covers to see if I have a broken valve spring of lifter? Pulled distributor(MSD) and all terminals looked good. Can get truck up to 90 but you can feel it misfiring. Think I might have dropped a valve?

you could put a vacume gauge on the motor and see if the gauge flucuates alot. if it does then you probable have a valve problem,and of course you could do a comp test, but it sounds like a valve