My '97 5.4 has developed a bad miss under load, it idles fine, but as soon as you put it in gear it begins to miss, mostly under a load, once it hits overdrive it bucks and misses badly. Ran fine a few days ago. I suspect a coil/plug but any other ideas greatly appreciated . Is there anyway to check the coil packs with a meter? I'm not getting an engine light, and got no stored codes with a scan. Thanks guys.

pat:santa:

 

Yes it is a coil pack, just go buy one and replace them one at a time, thats about the easiest. Unless you go to autozone, they will read the trouble code and tell you which cylinder pack is misfiring.

 

I had the same problem on my '97 - turned out to be a plug wire. If they are the originals, I would change my plugs and wires before I went to the coil packs (you only have 2, btw, in the front of each valve cover - not direct ignition, or "coil over plug" for each cylinder). There are some very good posts here on how to change your plugs, just do a search on "spark plug" or something similar.

Good Luck!

Jamie D.

 

The 97 5.4 has coil on plug...

 

Thanks guys, will I get a code if its a coilpack? Went to autozone and it showed no codes. Thanks again.

 

Sorry.....missed the engine size.........

Looks like you'll be chasing coil packs. If you can afford it, I believe Troyer performance will sell you an 8 pack of coils for a good bit less than what a parts house would charge for them individually. Then you can change your plugs AND coil packs at the same time, since you have to remove them to get to the plugs anyway.

Sometimes misfires throw codes, sometimes they don't. Mine did, I tried fixing it then cleared the codes, the problem returned, but the light didn't. I then tried something else to fix it, it didn't work, but it finally decided to throw a code. Go figure.....

 

Probably the easiest way to determine if it is a coilpack is to unplug them one at a time and see which one does not effect your performance. The one that doesnt change anything would be the one you need to replace.

 

We changed the plugs today thinking that was the problem, truck ran great for about 5miles then started right back bucking and running rough. I thought the plugs were the problem because of no engine light but maybe I was wrong. I'll start checking the coilpacks and see what I can find. Still cant figure out why the truck straightened out for a few miles then started missing again. I'll let you guys know what happens.

pat

 

I found this post when researching a miss on my 98 with 4.6L. It worked for my truck. I repositioned 2 wire bundles from touching the A/C accumulator. One was touching near the bottom by the wheel well, and the other was near the top of the accumulator.
coptercop

Here is the post that helped me

PKRWUD
Senior Member

Vehicle: 1995 Ford F150 Supercab Eddie Bauer

Registered: Sep 1999
Location: Ventura, California
Posts: 1910
Post FYI: 5.4L F-150 Owners...

Greetings

I just thought those of you who own F-150's equipped with the 5.4L engine might like to know about a recent problem that has been developing, and the cure. There have been quite a few cases lately where the trucks will suddenly run rough, have what feels like a miss, have a surging condition, cut out and trip the MIL (check engine light) and give a P1120 code. This problem has been particularly difficult to fix. It is usually traced to the TPS, but replacement fails to fix the problems. As it turns out, the problem is that the computer wiring harness sometimes rubs on the A/C accumulator. The fix has been to simply pull the harness away from the accumulator, and tie it so that it stays that way. Just thought you might want to know.
Take care,
-Chris

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'95 Eddie Bauer F-150 SC & '64 Falcon/Ranchero
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