Hi all, I'm new to the forum and I need some help with my 1997 Ford F150 4X4 with 5.4L engine. It idles good, and runs down the highway good. But when you are cruising down a road say at 35mph where the rpm's are around 1000-1400 it runs rough and the rpms jump, kinda like chugging. I was getting a EGR Flow Excessive, so I replaced the EGR controller and the EGR valve, no change, except is idles good now. When the truck is in park, I can bring it up to a high idle, around 1200 and make it chug. It only does this between 1100 and 1500 rpms, in both drive and park.

 

Sounds like a low grade misfire, when is the last time you changed the cops?

 

What are cops? If they are the thing that goes between the coil pack and the spark plug, mine has the one piece coil pack/plug tube. As far as I know, the spring and tube, aren't replaceable without replacing the whole coil pack. Last time I had a misfire, I got a code, and replace the coil pack and plug, and the code went away. #7 & 8 have both been replaced. May have a plug breaking down. That is the next step in my maintenance schedule. Truck has been a good one, 235,000 and only new A/C compressor, 2 Coil packs, and rear diff reseal.

 

Okay so the CoP's are actually the coil pack that goes on the the plug, the whole unit. Number 7 & 8 have been replaced. They both gave me fault codes when they started going, and were replaced along with the plugs. Is there a way to test these coil packs to see which one is going out when you dont have a fault code? at 45-50 dollars a piece, I cant just go changing out parts.

 

Hey did you ever get this one figured out? I've kinda got the same problem going on with my truck. thanks!