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What causes misfire code on cylinder one already changed plugs;boots;coils help.

(1996 Buick Skylark)
in Culpeper, VA on September 25, 2011
reading is a misfire on cylinder one i have had the spark plugs changed the boots changed and the ignition coils changed and the starter replaced. what else would and it is still loosing power and cutting off.
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Popular Answer
of Greg Solow's Engine Room on September 25, 2011
A misfire in one or more cylinders can be caused by ignition, fuel or engine mechanical issues. You could have a vacuum leak (intake manifold gasket or small vacuum hose near that runner in the intake manifold. Check the basics make sure the engine has "even" compression (intake /exhaust valves sealing well/correct valve clearance ect... compression and cylinder leakage tests confirm engine mechanical integrity). A misfire in one cylinder can be caused by a restricted or clogged fuel injector not supplying sufficient fuel to that cylinder (low fuel pressure or volume due to a bad fuel pump would affect all cylinders). Loss of ignition to a cylinder will cause a misfire (plug, coil. plug wire ect... or triggering of the ignition coil issues). I like to look at freeze frame information or live sensor data on a professional grade scan tool to look at fuel trim values long and short term and other key sensor data that can be read right of the scan tool without having to do intrusive testing at each sensor.
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