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1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

99 4.6L rough idle, acceleration

 
Old 03-10-2019, 05:03 PM
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Default 99 4.6L rough idle, acceleration

I have a 99 F-150 with a 4.6L & about 120K miles. When I would sit at a light it would sputter a little now & then, & if i stepped on it sometimes it would misfire. I tried some Sea Foam which seemed to work for a bit but one morning it began running rough while accelerating & the service engine light came on. I cannot check the codes, because for some reason the reader is not wired. I have changed the plugs, wires, coil packs, EGR valve, sensor & hoses. It now idles smooth until putting it in gear. It runs rough in gear or when I rev the engine. Any ideas?
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Old 03-10-2019, 07:22 PM
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check the fuel filter
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Old 03-17-2019, 03:04 PM
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Changed the fuel filter, no change. Idles ok but sputters when you rev it at first, then fine. Put it in gear & it begins to idle rough. Could it be an injector?
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Old 03-17-2019, 03:28 PM
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Yea, snake-oil is never the answer.

If you can't scan it, that should be a priority fix. Take it in, they'll clean the terminals for yuh and check feed/communication. Could have a PCM problem, it happens and why it may be acting up.

Other than that, the first thing to check is fuel...fuel is always first, it's a good by law and saves time and money.. With that, check fuel pressure. If weak, change fuel filter and re-check. If pressure is below 32 psi, time for a new pump. It was common for the original the pumps in these models to begin to go south anytime after 90,000 miles.

Last edited by Jbrew; 03-17-2019 at 03:30 PM.
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