troubleshooting

1997 FORD F-250
135,000 MILES • V8 • 2WD • AUTOMATIC
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ANNABELLE
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  • 1 POST
my truck (Ford F250 heavy duty) starts shaking and loosing power after driving it for about an hour on the highway. The transmission has trouble shifting gears when this starts happening. This is new and started over the last 300 miles on a long drive. There is a small oil leak most people thing is a seal. I had the transmission fluid changed 500 miles ago. The check engine light is on--it was read as a couple of random misfires on cylinders 1 and 2. When this happens the gas mpg drops by about 50%.
Nov 25, 2010 at 6:47 PM
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ERNEST CLARK
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  • 1,730 POSTS
Your tranny is probably fine. There's two kinds of misfires: Ignition and lean (fuel).

Always start at ignition by looking at plugs, wires, coils, ignition module, sensors, in that order.

If ignition checks out, move to fuel: pump pressure, fuel filter, pressure regulator, vacuum lines and fittings, injectors, sensors in that order.
Nov 25, 2010 at 7:19 PM