bad miss
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Logistics Pro
Joined: Jun 2009
Posts: 4,116
Likes: 6
From: metairie, LA
bad miss
iam looking at picking up a 97 expedition from a friend of mine. it has a 4.6 with the coilpacks on the front of the engine. how do i determine what or where the miss is from? thanks.
Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
You should begin with a complete tune up, starting with an accurate vacuum reading at idle and on the road, take a fuel pressure reading with the engine running and also after it is off, then do a compression test to see if there is any problems with a specific cylinder and read the spark plugs. Look for an fouled plug, possibly from a bad injector. As a maintenance procedure you should change the fuel filter at this time. If the compression test is good and the vacuum appears okay you should change the plugs and plug wires at this time. On a truck of this age the plugs and wires are the first suspect but, if you do a tune up the way I described you will have a good idea of the engine's condition. Good luck with it and let us know the results.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
Likes: 0
From: Boston, MA
a few thoughts. do you have any codes. codes might narrow down what cylinder is the issue. if you find the cylinder you can pull the plug and check it. you also can swap wires( if you have them) and see if the miss follows the wire.
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Logistics Pro
Joined: Jun 2009
Posts: 4,116
Likes: 6
From: metairie, LA
well, i changed the 13 yr old wires, and not much newer plugs... runs great. iam gonna change all filters and flush/change fluids, belt and clean throttel body this weekend. any more suggestions befor i put this thing on the road? it may have a 600 mi trip comming up next month.
Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
well, i changed the 13 yr old wires, and not much newer plugs... runs great. iam gonna change all filters and flush/change fluids, belt and clean throttel body this weekend. any more suggestions befor i put this thing on the road? it may have a 600 mi trip comming up next month.
Glad it's running great. All of the service manuals will tell you how to read the vacuum gage, if it's showing 17 to 20 inches mercury at an idle and is fairly steady it's good. Compression is a matter of the compression ratio and valve timing. You could have as little as 90 psi all across and it would run okay. Higher is better, and the variation between cylinders should not be more than 10%.
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Logistics Pro
Joined: Jun 2009
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From: metairie, LA
well this is it. all new plugs, wires fluids filters, speakers, bumper, got a set of EB seats from craigs list for $75, tires on the way, etc...
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Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
well this is it. all new plugs, wires fluids filters, speakers, bumper, got a set of EB seats from craigs list for $75,
Seems like you got a great deal, good for you, it's looking real good too.
Seems like you got a great deal, good for you, it's looking real good too.
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