Just returned from a long trip to Texas. The truck ran smoth as hell the whole way there. Changed the transmission oil about a week before I left and shudder was gone (BTW, thanks to all the people who had input on that topic!!). Got back into town and all of a sudden, the darn thing started running rough. Yesterday, the check engine light started flashing and I could tell it was missing. This happened once before and all it ended up being a loose plug wire. Checked that, but it didn't appear to be the problem. What do you think I should try next? Plugs are less than a year old.

BTW: 98' F150 4x4
4.6L 150,000miles

Thanks

cc21

 

cc21,
There are a lot of things that cause missing but the check engine light flashing usually means a miss-fire at the plugs. The very first thing to do is push each of the plug wires down over the plugs to see if one has backed off. This started happening to my truck after my first plug change and continued until I switched to Taylor plug wires. After that you will need to start pulling plugs to see if one is loose or fouled out. I think you will find your problem in one of these two areas.
Good luck.

 

Thanks WLF. I just checked the code and it is the #4 cylinder that has missed. I will start there and see what happens. What plugs and wires do you reccommend? I put a set of motorcraft plugs in about 4 or 5 months ago, and I used wires i got from Auto Zone ( I would be willing to bet it's the wire going to #4)

 

I really like Taylor wires but they are a little pricy.
Motorcraft or Autolite Plugs are both decent so don’t worry there.
I think the most important thing is to use dielectric grease (spark plug grease) and coat the inside of the plug wire boot before putting it on. It's a tough job getting the wire all the way on the plug and the dielectric grease helps and also prevents misfires past the boot to the block. Later it will help get the boot off.
I would try the dielectric grease first. Any good plug wire should last for a while.

 

Well, that didn't work. I'm thinking of trying the wires, change em all. What about plugs? If I change the one on #4, should I change them all?

 

If you still have your old wires use one of them to replace the #4 wire. If not then the cheapest thing to do is change the plug first. If that doesn't work then change that one wire. I would do one step at a time so you can identify the problem (change only the one plug wire then start the truck to see if it is fixed later you can to the rest if you want).
I don't think it would be the coil pac since that should affect all 4 of the cylinders running off of it. I don't think I would change all the plugs if it turns out to be the plug. 6 months is just not enough time to wear out plugs, one could have been bad or damaged in instillation.

 

Also don't forget you will have to disconnect the battery and turn on the lights for a few mins to clear the computer and turn off the check engine light.

 

Just pulled the plug and it looked like normal wear. While it was out we ran a compression check to see if I may have had a dead cylinder and the compression was fine, in fact the guy who did it said it was great for a truck that has 150,000 miles on it. When we put the plug back in (the same plug) and put the plug wire back on I didn't miss a lick! Don't know what the heck that was all about, but it's fine now. I wonder if maybe the wire is bad and moving it around caused it to make good contact or maybe the boot wasn't seated completely on the plug? I have no idea.

 

CC21

I had the check engine light for missfires come on frequently in my 98. I changed all the wires and plugs, and the check engine light still came on . The only thing that cured it for good was an injector cleaning, the kind that is done on the fuel rail. If it is a high milage engine, it may need it.

Good luck

 

Do I need to go to ford for that?

 

cc21,

I'm glad it worked out for you.

You may be right about the plug wire. My Jacobs wires would back off and fire to the block constantly.

My Taylor wires were about $90 for the set but appear to be worth it. Might be something to consider for future mods.

Maybe someone else here can tell you about some good wires.

 

my 97 has the same problem with both the #3 and 4 cylinder. Solved by canging the plastic cowl damn qhere hood meets firewall. However 2 times in last week with number 2 cylinder... Moisture seems to be my problem. Not even so much filling spark plug chanber as before. Now it seems to be condensation (lots of rain incHICAGOLAND THIS WEEK)...Are you experiencing the mis-fire when moisture content is high??

If so, let me know as this one has me really frustrated.