I have a 2007 super duty with a 5.4 it has 93000 miles on it. When you start up a hill it will shuter like it is missing but check engine light is not on could this be a coil and how would check for a bad coil if check engine light is not on to use meter. thanks for any help Darrell

 

The first thing that I would suspect is spark plugs. It's when an engine is under heavy load that the cylinder pressures can increase to the point where the plugs won't fire if they are worn badly..

 

You will have a misfire counter on the scantool. Even if you dont have a CEL it will count the misfires on all 8 cylinders. So you can see which one is acting up. I agree sounds like a plug or a COP, a coil or boot, if you narrow the misfire to a cylinder remove that plug and look at the porcilian around the plug, you may see a carbon track going from the top to were the nut is. Check the PVC hose too, they rot out at the back of the intake causing a lean condition as well.

 

They may have never been replaced. The mileage is probably getting to the range where they should be. I'd plug it into a scanner to check for misfire codes even if you haven't seen a CEL.

 

Agreed. You can still pull a code with no CEL on. My truck did that a few months ago... had a bad coil on # 7.

 

Had a CEL on my '07 Crown Vic. Misfire # 8 cylinder. Replaced coil and problem solved. It came back a few days later, but the CEL came and went out again.
Scanner said #8 misfire again. Checked the plugs. Car had 112k on it and I'm sure they'd never been changed. The gap should be .054 on them but each plug was well over .080.
Replaced the plugs, made sure they were properly gapped and put dielectric grease in all boots and it's been good for 7-800 miles so far.

 

also see if you have water in the plug boots, I had to replace the boots (liners) because water was entering them and shorting out the plugs. cleared the issue....

 

How I check the coils is to start the engine and let it idle and then take a coil loose. If the idle changes, the coil is good. If there is no change in idle, the coil is bad. At 100k miles you are due a spark plug change anyways, so I would do that first and see if it fixes the problem.

 

thanks for the info I will change plugs some thing I am not looking forward to. I hear it is a bear and to be careful doing it not to brake them. I will put penetrating oil around each plug and let it set overnight. This is what I was told. thanks Darrell

 

Although not quite the same motor in my Crown Vic, I'd read that it's a good idea to put Permatex copper anti seize on the threads of the new plugs. Not an expensive insurance policy for future removal so I went ahead with it.

 

my 06 did the exact same thing. I changed the coil packs the problem was solved! On the other hand, it may be the plugs. The plugs are an absolute nightmare. So try a set of coil packs first, you can change those in about an hour or so.if you are considering changing the plugs, do a lot of research. One more thing, when my truck had a miss because of the coil pack there was no light on the dash nothing could be pulled from the computer with a scan tool. The problem was intermittent, only uphill under load.

 

I disagree with changing the coil packs at this point. With 93k mikes on those plugs, they should be replaced... Yes they can be a real b!tch... You may want to consider supporting your local Ford Dealership to have this done.. At the same time, they can determine if you have a weak coil and replace it as well..

 

I started getting a misfire under load at about 95K miles, I swapped COP but was never to track it to a coil changed plugs and all have been fine for the past 25k miles.

Get a quote before you take it in for a plug change, my quote was $400 - $900 depending how many plugs broke. I purchased a Lisle 65600 tool about $60 used it on the three plugs that broke sold it on ebay for $50.

I assume you have the two piece plugs that like to break.