Hello all. I have a '98 F-150 with the 4.6L V8 in which while driving today the check engine light started flashing. At that time I was at low throttle/coasting while stuck in traffic. Upon throttle up the light became steady and has remained on since. I noticed some slight hesitation when the light came on so suspected cylinder misfire. This has happened in past but not with the light coming on. Before it would seem to hesitate when started up after sitting outside during rainstorm. After a minute or two the hesitation would go away and drive normally. So after reading some posts on here it sounds like I'm getting moisture in the coil pack. I had Autozone hook up their scan tool and it diagnosed Cylinder 1 misfire. He suggested checking out the coil pack. My question is, since the problem happens when moist conditions are present and seems to go away after some driving, would this indicate a faulty coil pack and not faulty spark plug/wires? If I do need new coil pack, should they both be replaced? Now once the problem is resolved will the check engine light automatically shut off or does it need to be cleared via scan tool?? Thanks for your help!

 

When the SES flashes it means you're more than 1.5 times the FTP standard. If you're below that threshold the lite will come on and stay on steady. Ford coils are notorious for failing and some cylinders do get water in the spark plug/COP port. If you do you'll see rust on the spark plug or the COP boot or on both. As far as resetting the DTC is concerned you can wait to see if it goes out on its' own. It will go out if your repair solved the problem. It it didn't cure the problem that resulted in the lite coming on in the first place the lite will stay on. Some auto techs like to turn the SES off to see if it comes back on, but that only helps if you have your own scan tool that stores Freeze Frames which Auto Zone doesn't have. They wouldn't know where Freeze Frames were for even if their scan tool could display them.

 

So if it is just a moisture issue I could wait for a dryer day, start up truck and the light may turn off on its own?

 

If it is moisture related, you need to probably replace the coil boots.

 

yea defiantly moisture related and i do believe its in the coil pack. If you replace the coil pack put a new spark plug boot on it and the code will have to be erased and have you got an oreillys in your area if so give them a try they carry bwd ignition parts there really good stuff

 

You might start by pulling the plug and taking a look at it. Especially since #1 is pretty easy to get to. Make sure both ends of the plug wire look good ('98 has wires not COS, right?). If all those things are good, you canb try swapping coil packs and see if the problem moves.

 

You could also move to Arizona. The lite may go out on its' own, but that doesn't fix the underlying problem. You need to find the source of the leak and fix it. In the short term you should replace #1 plug and swap the #1 and #2 COPs to see if the problem has moved the next time the SES comes on. If it does move to #2 replace COP at #2. Don't forget that you could have problems back at #1 the next time you get a heavy rain.

 

I am fighting this same issue for the second winter in a row. Truck runs fine in the summer, rough in the rains of winter. Leak is not from the heater core. It must be rainwater from around the hood. I thought I fixed the hood leak this summer. Same problem again. Anyone have any good ideas on finding this leak,which causes multiple "Cylinder Misfires"? Besides taking it the Ford dealer?