99 4.6L rough idle, acceleration
03-10-2019, 05:03 PM
#1
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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?
03-17-2019, 03:28 PM
#4
Senior Member
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.
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.
