99 Expedition missing occasionally...
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Junior User
Joined: Mar 2005
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99 Expedition missing occasionally...
I have a 99 EB with the 5.4, 126k on the clock. It misses from time to time, if I let it sit for a day or 2 it will start missing, running like crap, and idling really rough for like 30 mins and then it goes away, if I drive it everyday then nothing happens is only when it sits for a while. I havent gotten any codes so I really dont know what to do. Anybody knows whats causing this thanks in advance.
Senior User
Joined: Dec 2003
Posts: 141
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From: kansas city kansas
My 97 expy with the 4.6 does that if it sits for a day or two but only takes a few mins to run correctly. Have never been concerned about it on my end though cause it is not often that it sits too long.
Hotshot
Joined: Jan 2004
Posts: 19,765
Likes: 1,082
From: St Louis
You have a mild misfire. The unburned fuel is dumped into the cat where the cat has a hard time processing it. The unburned fuel and inefficient catalyst action results in the hydrogen sulfide smell.
Probably old/worn/improper plugs, maybe a COP on the 5.4.
If you can force a misfire while driving and get the MIL to light/flash, you'll find it easier to identify which cylinder(s) is at fault. Otherwise, you'll have to hook it up to a capable scanner that can read Mode 6 data.
Steve
Probably old/worn/improper plugs, maybe a COP on the 5.4.
If you can force a misfire while driving and get the MIL to light/flash, you'll find it easier to identify which cylinder(s) is at fault. Otherwise, you'll have to hook it up to a capable scanner that can read Mode 6 data.
Steve
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A proper scanner so Im going have to take it to ford to get it checked out. My mechanic only has a comp and he told me if is not throwing a code I wont know what it is, if it missfires then it should throw a code but i guess not. Thanks alot steve for ur reply.
