Help!!!

I know someone on here can help me. I have a 01 F-150 Supercrew with the 5.4L and 4X4 and Auto trans. It has about 85K miles on it and last week it started acting wierd. If I turn on the A/c when the engine is cold (not warmed up), the engine acts like it wants to die. It rattles and misses. Turn off the A/C and it clears right up. I am confused because when I say the engine is cold, it is sunny California here right now so I am not dealing with extreme cold temps. It just like to warm up before I run the A/C. Today, the problem seemed to take another step up on me as coming to work this morning, with the A/C off, I set the cruise on 72MPH and it would surge. Kind of like a cruise control module going out or somehting. Closer to work, it also cleared up, so I am stumped. Any help or advise would be greatly appriciated as I am planning a very long trip in the next month or so and will be pulling my boat so I need her running strong.

On a side note, replaced the brakes this weekend (due to the typical Ford warped Rotor effect) and found out something kind of cool yet odd. Before I did the brake job, I noticed my Em. brake light would not go out despite the brake being completely released. I had a hunch that maybe Ford tied in a low fluid sensor to that light and low and behold, they did. Added some fluid and the light went out. Did not take much as I knew when I changed the brakes, I would have some spare since the pistons in the calipers would be fully compressed. Just thought I'd share. Chuck.

 

Pull your codes.......

 

Had a similiar prob, changed out the COP's, problem went away

 

There have been known cases where the cabling that comes to close to the A/C dryer canister have caused a missing condition.
Check this out and use a tie wrap to keep the cable away from the canister.
I believe it to be a static charge condition on the canister that screws up the computer by jumping to the cable.
The canister is isolated from ground in it's mounting and by rubber section in the hoses.
Give it a try and let us know.

 

Might be just missing the boat here, but what is a COP? Probably something simple and I am just very dense. LOL. Thanks for the ideas everyone. Like I said, it is only with the A/C on. I have been running without it for the last two days and she runs fin. The Cruise Control appears to be an unrelated issue as it still surges but I am sure it is something with the regulator. I will have to trace down all my vacumn lines to make sure something has not come loose. I will be sure to keep everyone updated. Thanks again.

 

Chuka,

Here's something else to try:

if you look into your engine bay, the plugs are number like this:

4 8
3 7
2 6
1 5

Right above #3 and 4 cylinders, there are air conditioner refrigerant lines. The low pressure line ( the big one) sweats profusely when the air conditioner is running. The more humid the outside air is, the more it sweats. It could be dripping water onto the top of the COP (Coil On Plug). See, these trucks have a coil on top of each plug. They have NO distributor. These COPs seem to be VERY sensative to water. I would pull the #3 and #4 COP and check tops of them for any cracking. If in doubt, change out these two. They are about $50 each at Autoze / Advance. Check the plug wells for water. If water gets in there, the spark plug will misfire occassionally--not enough to throw a code in most cases. Put a fresh set of spark plugs in and let us know what happens.

Hope this helps,

Sidewinder

 

Thanks for the clarification Sidewinder. I will check into that this weekend. Hopefully it is somehting easy to fix so it does not have to go to the mechanic. I really appriciate everyone's help. Thanks Guys. I will keep everyone updated.