rough running

[bostonshouse]

Glad to be part of the forum and hopeful that someone can help with my issue. I have a 2006 expedition limited. It was running fine normally but had an intermittent issue with a slight miss under load which threw a code for a coil issue on the number 3 cyl. I replaced the coil and the issue went away almost completely. I decided to let my local shop replace all the plugs. That is where the problems started. The expy now idles terribly with a noticeable miss. It improves under acceleration. It is not throwing any codes and the shop is stumped. The rough idle is noticeable in park and neutral but really bad when idling in gear. Problem started immediately after having plugs changed. Any ideas?

 

[Am3ricanInfid3L]

Check the gap on those new plugs.

 

[Stanger4Life]

Check the plug gap and make sure the plugs are snug in the hole. You may else want to reset your PCM (long shot, but worth trying).

Also, do you happen to have the old coils and old spark plugs? If you do I would start with putting the old plugs in or coils first to see if it changes anything. I'd start with the coils if it doesn't make the problem go away significantly better then there is something wrong with the spark plugs. Then throw in the old spark plugs with the new coils and it runs horribly then something with the coils. In any case the problem took place after this was done, so either it's related to the spark plugs/coils or you have a vacuum leak somewhere which is also very possible, however this usually will trigger a check engine light since it's screwing up your Air/Fuel ratio.

 

[2005exp]

New coils and plugs do not mean they are good.

A good shop should know how to find the bad one's ??

Elementary.

 

[jdecker]

Has the shop checked to see if there are any pending codes?
My guess is they have knocked either a vacuum or pcv line off while they were installing the plugs.

 

[adirving]

sounds like what mine was doing. I needed to replace a vacuum hose.