engine runs rough

Reply Subscribe

Thread Tools

Search this Thread

Aug 23, 2001 | 09:13 AM

exped

Thread Starter

New User

Joined: Aug 2001

Posts: 9

Likes: 0

engine runs rough

Have a 98 Expedition with 36K miles. The engine is not running smoothly. When idling, the engine seems to misfire on an irregular patern. When accelerating, it feels like it will shake apart. No engine check light. Filters are clean. Replaced gasoline. Any ideas on what it might be or how I might narrow the search down? Thanks for any suggestions.

Aug 23, 2001 | 04:42 PM

paul99expy4

New User

Joined: Aug 2001

Posts: 2

Likes: 0

engine runs rough

If you have the 5.4L it could very likely be one of the ignition coil packs that is defective. I understand that you will not get a fault light until it misfires continuously for 2 min. My #2 coil pack went out with 62K and OEM part cost $100 from Ford. Can get aftermarket coil for about half that. Not a fun job if one of the back ones. The 4.6L has one coil for every two cylinders and have not heard that they are experiencing the same failure rates. Keeping them dry is the key...don't drive in the rain!

Aug 24, 2001 | 07:42 AM

exped

Thread Starter

New User

Joined: Aug 2001

Posts: 9

Likes: 0

engine runs rough

Thanks. I changed the fuel filter yesterday and after about 5 minutes on the road it seemed to smooth out. This morning, I still notice a slight misfire during idle in gear. Funny thing about it is that it seems to come and go. Did see a check engine light yesterday before the fuel filter replacement when it ran so rough, I wasn't sure it would make it home.

If the fuel filter was the cause, do you know if a dirty one allows impurities to pass, or does it just restrict fuel flow? I'm thinking/hoping I just need to run it a while. Threw some injector cleaner in the tank.

Aug 25, 2001 | 01:18 PM

jakegypsum

Posting Guru

Joined: Sep 2000

Posts: 1,586

Likes: 0

From: Linwood, N.J. USA!

engine runs rough

I believe Ford had a problem with the airconditioning condensation dripping on one of the coil packs. Certain models. Rear, passenger side coil pack. The coil pack would crack, causing misfire, and have to be replaced. People hosing down their engines would also experience the same problem. Sometimes the engine would not even start at all.

Jakegypsum // Ford fleet, soup to nuts.

Aug 26, 2001 | 07:49 AM

exped

Thread Starter

New User

Joined: Aug 2001

Posts: 9

Likes: 0

engine runs rough

Thanks for the advice. I'm beginning to believe it is a coil pack. The misfire is consistent afterall, happening most often in high gear at low rpm and trying to accelerate (under load). Is there anyplace where I can get pretty specific instructions on replacing the packs and plugs. Looks like a lot of stuff has to come off to get to these components, especially the back ones. Also, can you suggest a good method to identify which is the bad one?

Aug 27, 2001 | 07:28 PM

jakegypsum

Posting Guru

Joined: Sep 2000

Posts: 1,586

Likes: 0

From: Linwood, N.J. USA!

engine runs rough

Exped, I am not sure. I never had to do it. Sorry. Jake.

Jakegypsum // Ford fleet, soup to nuts.

Sep 6, 2001 | 07:26 AM

exped

Thread Starter

New User

Joined: Aug 2001

Posts: 9

Likes: 0

engine runs rough

Took it to Ford. They replaced two coil packs and spark plugs (#3 and #4). Terrific dealership. Though my warranty had expired a couple of months ago, they did not charge me a dime.