I have a 98' Expedition with a 5.4l engine (each plug has own coil) and I am experiencing engine miss, sometimes quite bad (think shake rattle and roll the engine right off the frame) and dramatic loss of power at acceleration. Can pull over and turn the truck off, restart and it improves for a little while. Ran the engine light codes and got po304, po305, po306, po308 all at the same time. These codes mean that supposedly I've got 4 coil packs going bad at the same time. Is that probable, or even in the realm of possibility? The real kicker is that the truck at idle sounds and runs great....

 

Are all of those packs located on the same bank (cylinder head)?

 

CYLINDERS 4, 5, 6, AND 8

4 8
3 7
2 6
1 5

AS YOU CAN SEE 3 OF THE 4 ARE, BUT # 4 IS NOT. I'VE REPLACED #4 BEFORE, A REAL PAIN, BUT I CANNOT SEE HOW ALL 4 WOULD GO OUT AT THE SAME EXACT TIME. BY THE WAY MOST OF THE TIME I THINK IT IS ONLY INTERMITTENT MISFIRES, AS THE TRUCK STILL HAS REASONABLE POWER, BUT TWICE I THINK I LOST ALL FOUR CYLINDERS....THINK NO POWER AT ALL, ENGINE SHAKING OFF OF FRAME....BUT I PULL OVER TURN IT OFF, RESTART IT AND VOILA! NO PROBLEMO! FOR ANOTHER 20 MINUTES AT LEAST

 

I couldn't imagine 4 going out at the same time...especially #4 since it is relatively new. How many total miles on engine? Can you check voltage to each coil. I don't know what it should be, but it might be low.

 

Total miles are 99k, and I may have hit on the answer..been reading posts on people washing out engine compartment, and because of design (holes that hold water where the plugs and coils are) having multiple coils go out at once. Now I haven't washed out the engine compartment, but about 3-4 weeks ago we did have flood conditions in this part of the country and I went through overflow approximately 15" deep several times, thought it was fun at the time but...Stupid design on FORD's part for a 4x4 don't you think? Do you think that this might be part or all of the problem? Also thinking about fuel filter, as the truck idles fine, but under acceleration, different story...

 

Try the fuel filter. I just replaced mine because of the same problem. It was cheap and only take 5 minutes to install.

Eric

 

I replaced all four cops, and the fuel filter. Did the fuel filter first as it is the easiest and cheapest to do, drove the truck, no difference. Replaced all 4 cops, and HALLELUIAH!!! Praise God!!! It is fixed. Tested all four "bad" coils and cylinders #5, #6, and #8 did indeed have bad coils (resistance should be around 5500 ohms or less, it was over 7000) #4 though tested fine. Couldn't figure out why I got the code for 4 until I looked at the firing sequence. It fires the cylinders in this order 1,3,7,2,5,6,4,8. I guess because 4 is right in the middle of the three misfires it may have been affected also.

 

Hi,

I have a 99 Expy XLT with the 5.4L engine and on two different occasions, I've had a similar problem.

In both instances, the upper radiator hose leaked coolant onto the coil pack and I lost 1 or 2 cylinders. Engine light came on and it ran rough as can be, similar to yours.

Both times it was under warranty and the failed coil packs were replaced.

I don't think this would cause problems on both sides like you have but I think you have nailed it with your water idea.

I too find it annoying that a small amount of water would cause such a large problem.

Hope this helps.

Let us know what you find out and good luck...

 

That's terrible that they all were bad, but at least you have it fixed!

 

Wow! That's unreal.....glad to hear you got it licked.
Eric

 

how much are the coil packs a piece I have a problem with just one of mine #4 thanks

 

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COPs run about $50-80 bucks depending upon what you get. I get o'rielly's brand and they work great for about $54 bucks a pop. I think the factory once are motorcraft (i think) and are more expensive. Just for future reference.....

DO NOT SPRAY OUT YOUR ENGINE COMPARTMENT. I also learned this the hard way and started misfiring.

 

When my #4 coil went, it would run fine on idle as well but on acceleration it would run very rough and stumble. Sometimes my check engine light would come on but if I pulled over and shut the engine off then restart it would run fine for a while. Just so it never stalls upon putting in reverse again I'll be fine - what a nightmare!

 

I think you have hit it with the water problem as cause. I'm pretty sure a COP went bad each time I went through a car wash (2 x in 6 weeks)! I know 1 wash I paid for the underbody spray. Lousy Ford design that there in no evacuation on these spark plug wells. I wish someone offered a rubber boot of some sort to go over each COP. I plan to pack some dielectric grease before next car wash.