murdog

i have a miss in my 2004 f150 that i can't figure out. i am not getting any codes, checked with my edge evo and a hand held obdII computer. i have tried all settings and even back to stock and i can't tell a difference. i have noticed thAT WHEN i drive in the morning(cooler air) that it runs alot better, after work it gets bad, mostly at higher rpm's such as when i am going up hill or getting on to interstate. lower rpm's and just normal driving seems fine but if i step down on it it shifts down and gets louder but feels like i have several tons of weight behind me and it misses and puts a good bit. any help or ideas would be greatly appreciated

westtnfx4

Sounds like you have a Cop (coil over plug)on the way out...have you checked those? When the engine is hot and missing unplug each cop one at a time till you find the dead one(no change in the engine when unplugged). It's only one small bolt to take out...pull the old one out and replace with one from napa/autozone etc.

murdog

thanks for the help, it is not missing at idle so would that still work as i would have to rev it up to 3 thousand rpm's or so

westtnfx4

It will not miss (or be noticable at idle)...but you will still be able to tell which one is dead...(you will feel the engine start missing if it's a good cop that you have unplugged)they are wierd like that....matter of fact they won't miss usually till the engine is under a load at say 1500 rpms or so...

murdog

i will try that thanks for your ideas

dase520

i had the same problem it was my cylinder 4 and 5 replaced sparkplugs and the two bad coil packs! runs smooth now.

Hollywoodfish

I had that same issue about 4 months ago. It was a bad injector. Good Luck.

xJimbos

I'd bet on a weak coil. The spring inside of the boot that transfers the electrical pulse to the plug can get awfully rusted and deteriorated. You may just need to replace the boots on one or all of your coils. Your cheapest option is to buy 1 coil boot and a can of dielectric gel. Squirt some dielectric into the boot, in the middle of the spring and seat it around each COP. Really if you just pull the COPs you can look inside the boot and see how much rust is in there. If you have a 5.4 the drivers side tends to get more water and mud up into the engine bay and thus falls onto the top of the engine and into the holes where the plugs and COPs lie (yeah, I'm bad with names of engine parts). Could be a bunch of rust on your drivers side COPs.

How many miles are on your truck? If it's over 60K you might want to pull out the plugs and check them too...but we all know where that can get you and if you're not getting any "random misfire" codes or that check engine light blinking on and off then probably not the plugs. Although can you trust the computer all the time??? NO...

You could always replace the entire COPs too; I found a whole set of new ones on ebay for around 100.00, for all 8! I waited for a couple of weeks to find the good price, but it can be done. Patience is key.

What is getting at me is you say this doesn't happen in cooler weather. At all????? I mean, it's 70 degrees F outside and you smash down the pedal and you don't get ANY missing? And then if it's 95 degrees F you do????? I will think about that and search for a few ideas. But let us know, cooler air and no miss at all above 2500-3000 RPM???

murdog

yes there is some miss in the cooler weather but not as bad i just recieved my lisle sparkplug tool kit in the mail over the weekend so i may start on the drivers side changing the plugs tonite. Is there a way to check the cop's when removed from the truck?

tbspeed1

I have something similar with my 2000 f150 4.2v6 would that be the same as the coil pack?