Last night on the way home I noticed the truck hesitating/shaking/stumbling at low RPM's (less than 2000) If I really gassed it, the hesitation went away. As I was going up a hill the engine upshifted and went to low RPM's. It started shaking pretty badly then and after a few seconds the Check Engine Light started blinking. I pulled over and put the truck in park. The light turned off. I drove home. It continued to shake on and off but the light didn't come back on.

This morning I went to the autostore and attached the computer to my truck for a diagnostic. The only code that came up was a "pending" code P0455 which is a "Evaporative Emission Control System Leak Detected." But because it was "pending" I guess it isn't that bad yet?

Somehow I doubt that this is what caused the hesitation problem.

I did a search here and several other people with similar symptoms found that they had bad COP's causing a engine misfire. And the manual also says that the blinking light is an engine misfire.

I've only owned the truck for a week so I don't really know the history but I do know that it was a "Canada" truck so that means snowy and salty roads and increased corrosion which is why I also thought of the possibly bad COP's.

Could the computer have cleared the code because I waited overnight to drive to the auto store? Is there anything besides a misfire that could cause the blinking check engine light?

I am thinking it's the bad COP's but I don't know why the code didn't come up on the diagnostic? Should I just start by replacing all of the coils?

My truck has 109,000 miles on it and I found a receipt in the glove box showing that the spark plugs had all been replaced 1 year ago.

Any ideas?

Thanks

 

Well here's possible causes of 455 , I would fix this first -

https://www.f150online.com/galleries...238&anum=10939

However, On my 98 5.4L the same thing happened - blinking light no codes pending to do with "misfire" - I pulled my hair on that one. It kept doing the same thing and would quit blinking after awhile. I was driving the truck one day and was about 5 miles from Auto Zone and it flashed again, well this cheesed me off a bit and I just freakin floored it lol and it started to blink again after it quit just quit blinking a few seconds ago. I stoped by Auto Zone a second time for the same reason and finally there was a code in memory pointing to a cylinder, but what was strange is that I also recieved a Multiple Misfire Code. I ended up replacing all my COP's.

Hope this helps

 

Well, its a missfire.

Since there isnt a code telling you what cylinder(s) it is, you can simply unplug the COPs one at a time and see if any of them change the idle.

 

If your going to use the unplug one at a time deal, make sure it is misfiring when you try it with these COPs, they fail at certain loads and are flauless at others, this method has never worked for me. Unless you find one that isn't plugged in at all lol
Good Luck

 

I have found an inexpensive code reader plugged in and running all the time so you can instantly check the code is invaluable in instances like this.

 

I think you really got something there for "misfire" issues. True that, code readers aren't all that expensive when you look at the possible hell a misfire issue could put you thru on these motors - A cheaper way to do it yourself, monitor your own cylinder history, instead of that fancy brain picker with mode 6 used for exploring the EEC-V system.
Keeping an OBD-II SCAN tool plugged in and monitoring might pick up signals that otherwise, would escape memory.

Now you tell me lol..

 

Thanks for all the help.

Unfortunately, it doesn't seem to misfire a lot when idling for me to check the COPs one by one.

I think I'll just go ahead and buy 8 new ones and replace them all. jbrew mentions in one of the other threads (thanks jbrew!) a seller on ebay that sells 8 COPs and 8 plugs for $130. With my luck, I'll replace one and another will go bad in a couple of months anyway. I don't want to mess with it. I'll just replace all of them for $130.

And nearly everyone here and on other threads seems to agree that it is the bad COPs that causes this problem.

Thanks

 

Yup, Kevin @ Global will set you up - WARNING - If you don't tell him ahead of time what plugs you want with the kit, you will NOT receive the right one's - You have to tell him..

Also, I personally know of 3 trucks running these that I installed and they have no problems, I pulled them out of mine because I found Ford factory COP's for $20 more. Unfortunately, they didn't come with plugs - they all came with new factory bolts tho lol. However, I have heard of one person so far that received 1 bad coil from him, but you take your chances of that anywhere you go - so far there's only a 1% chance of that happening to you , go for it.

 

my truck is doing the EXACT same thing, i guess it looks like new coils for me

 

The blinking check engine light means spark plug misfire as you have found out. You should check the condition of the rubber boots to see if one is cracked. You should be able to see if one is misfiring.
Another thing to do is to purchase one COP and replace #1 cylinder. If that doesn't fix the problem then install the #1 COP on the #2 cylinder and so on until you find out which one is bad.
The COP failure rate varies so much that replacing them all does not guarantee you will not have a failure in the future. At the same time not replacing does not guarantee a pending failure. Fix only what is broken.