98 Merc GM 4.6L Bad miss

Problem has me stumped. Bad miss once car is warmed up. Scan tool says P307...have changed cyl 7 plug and coil boot assy. Problem always comes back to cyl 7. Think my next step is injector or computer? Is there some other diagnostic isolation I am missing? Ruled out the engine valves or piston because it does not act up until its moving down the road and warm. Any suggestions would be appreciated............jb

Reply to
<jb
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P307...have changed

next step is

Ruled out the engine

warm. Any suggestions

Sticking valve.

More common on the Triton DOHC, but a likely culprit after warm-up.

Maybe a treatment w/ Marvel Mystery Oil & a change to Mobil 1?

If you need an emissions inspection, you're in trouble, otherwise it's probably just a live-with situation on an almost 10-year-old car.

Rob

Reply to
trainfan1

P307...have changed

next step is

Ruled out the engine

warm. Any suggestions

Check very close for any moisture in and around the plug well. Any water leaks that dampen the wire but not enough to see without looking real close.

Reply to
F.H.

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