Good evening Ladies and Gents!

I'm new to the forum, and am looking for things to try with my misfiring F250 if anyone has suggestions please It's as 2001 5.4L gasoline automatic with almost 90k on it. Everything is stock, bar the cat-back system.

I noticed yesterday that there is now a misfire. It sounds to me as though it's only on one cylinder, but I could be wrong. It does it very little at idle and seems to be worst at fairly low revs on a moderate hill climb, where it becomes more pronounced and a lot less intermittent. At higher revs it is a lot less obvious.

So.... a couple of questions if I may:
There is no check engine light, but then, would a single misfiring cylinder make the light come on?
Would there be a code that could be read from the OBDC?
Could it simply be some dampness with the weather change? If so, is there something that I can spray on or around the plugs and spark packs to drive the damp out?
Is it a spark pack breaking down, and if so, is there a way to test this?

I'm fairly capable technically and mechanically, and do my own brakes, belts, wheel bearings, oil changes etc... also not afraid to get under the lid and start tinkering!

Thank you in advance for any suggestions!

Onesprint

 

Hello Onesprint and welcome to FTE.

It takes a lot of misfires to light the Check Engine Light (CEL) and set an error code. However, if you have a decent code scanner you can check for PENDING CODES. A few misfires will show up as a pending code, which will guide you to the offending cylinder that is misfiring.

At 90k miles, you are about due for a tune up, so the appearance of a misfire under load does not seem out of the ordinary. I would change all the spark plugs and boots, then see if your misfire disappears. If not, then find a scanner to read the pending codes. When you find the offending cylinder, switch the COP (Coil Over Plug) with another cylinder and retest. If the code follows the COP, then you know which COP to replace.

 

You may want to replace the cables and plugs with the age and miles.
Get good ones not the cheep stuff. Put a little anti-seize on the plug
threads so the next guy does not have to deal with stuck plugs. Also
use some dielectric grease on the cable boots to help them. If that
happens to be you then your will be much happier the next change.
You could also be hearing ping. Try to get your gas some where else.
Let us know if this fixed it or not.

Sean

 

Do have an OBD2 code reader? They cost $100 to $250 for a simple model (they can't read everything) but they really do help. Got friends who might have one? I loan mine to friends at work......Unless you have endless supply of cash the Snap-on one that can see it all, their like $10,000.

I have had code mine can't it doesn't do ABS.

I have experienced the MIL light does always com on when there is a trouble code (DTC).

With out the code(s) your working blind. The 5.4 is distributor-less, some the things that could come into play Crank sensor, cam sensor, coil pack, bad wire, bad plug(s) etc. It could be getting starved for fuel. Clogged fuel filter.

Bottom line go for the codes first.

 

After 90K miles I would install new plugs and replace the boots.

Denny

 

Wow! Thanks for the responses folks!

So the consensus is plugs and boots, but that I should get the OBDC read before I really get going. I don't have a code scanner (homeowner), but I may be able to locate one and give it a go.

Sounds straightforward enough. Is there anything that I should really watch for when doing the plugs? I have heard the horror stories about Ford plugs blowing out, stripped heads, that kind of thing. Also, is there a particular brand of plug that would be recommended for this engine? How many in/lb (surely not ft/lb ) for the plugs?

I don't hear any pinking, even under load.
I did change the fuel filter when we bought the truck 26k miles ago so unless there is a bad injector somewhere? There is no problem getting going when the pedal goes down. No hesitancy, it just goes, so maybe fuel starvation is ruled out.

Thanks again for the replies, I now have some stuff to try before the Missus starts up with "Sell the truck"....... Nope. I like my truck, it stays.

Let you know what I find

Onesprint

 

Stick with the Motorcraft Platinum plugs. These engines really do work better with what came from the factory.

 

Doing plugs and boots is a good thing but I'd put money on at least one of your coil packs being bad. (My company truck is doing the exact same thing after plugs and boots less than 1 month ago. It's at the shop right now getting cylinder 7 coil pack changed. They have nice scanners at the shop.)

If you don't have a scanner, just buy one coil pack, replace one existing coil and see if problem goes away. Move known good coil to next cylinder if it doesn't fix the problem and try again. I did this recently with my V10 Excursion and got lucky and swapped the bad one out first try!

 

Exactly. You are due for plugs anyway at 90K.

 

Firstly, my apologies for not updating here sooner.

So, I finally got moving on it, and removed all the COP modules only to discover that #7 hole had been under water at some point in history. It was bone dry when I got into it, but the whole area around the COP and down into the top of the plug was coated in orange rusty coloured powder, and the boot was all hardened and crusty. Can't tell if it was from coolant or from a leak below the windshield that had come and gone. Can't get the picture to post though. Anyway, I gave all the holes a good cleaning out with air, which made a big difference to the appearance.

After staring into it for an hour or so, I have to confess that I got very nervous about stripping something while removing the plugs and leaving the truck stranded at home, so decided that I would put it all back together and let my local shop replace the plugs, and it could be a headache for someone else. I gave the boots a good cleaning and lubed them up with a little WD to soften them a bit, and put it all back together..... no misfire.

I ran it for a few days without issue, but finally got it to the shop. $300 for plugs and boots, peace of mind, and it now runs like a champ. So much more responsive. I had no idea!

My thanks to all for your responses to my original post

Onesprint