1990 Ford Bronco Misfiring

1990 FORD BRONCO

154,000 MILES • 2.9L • 6 CYL • 4WD • MANUAL

BRONCO2JACK

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I have a 1990 ford bronco 2 that is idling rough and sounding like it is misfiring. I have replaced the o2 sensor put new plugs in it and cleaned the ignition sensor but no help. When i give it gas it has no power and makes a knocking sound every once in a while when accelerating. I am going to put on a new fuel pressure regulator soon to see if that helps. I also put sea foam through the system to try to clean out the injectors.
Any ideas?
Thanks

Oct 7, 2014 at 1:00 PM

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CARADIODOC

AUTOMOTIVE REPAIR CONTRIBUTOR
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Replacing random parts is not a good way to diagnose anything. First I'd consider grounding each spark plug wire, one at a time, to see if only one has no effect on how the engine idles. If each one makes the engine idle worse when it's disabled, suspect a fuel pressure problem or erratic ignition timing. If one cylinder doesn't cause a change when it is disabled, perform a compression test. Burned valves, a worn lobe on the camshaft, or a worn rocker arm will cause a misfire.

If your engine uses a knock sensor, a mechanical knock that you're hearing will lead to the Engine Computer retarding ignition timing, and that will reduce power.

Oct 8, 2014 at 1:00 AM