Ford 4.6 Misfire w/CEL on

[SeaKaye12]

Hiya All,

Well; the 1998 Ford F150 (4.6L) pretty much sits in the driveway these days; except when I pull the trailer.

The last time out; I started to feel (very noticeably) a mis-fire. Then; the CEL came on. Sometimes it blinks, and sometimes it is steady.

What's apt to be wrong?

What is the significance of the Blinking vs. Steady CEL?

Any suggestions?

 

[SpinnerBait_Nut]

Re: Ford 4.6 Misfire w/CEL on

Take it to a local parts house and have them pull the code/s for you.
There are several things that could cause the mis-fire.
Need the codes to help.

 

[204 Escape]

Re: Ford 4.6 Misfire w/CEL on

"Could be" one of the coils, (I think that they are called COPS). That's what my 5.4 has done in the past. Depends on where you get one, on the price, BUT, you need the code !!!!! Auto Zone, can do the code check for free.

 

[SeaKaye12]

Re: Ford 4.6 Misfire w/CEL on

OK...update:

There's an Autozone in my town, and they have a really cool deal: You can purchase their code-reader (they charge $149.99) and go and use it, and then you are free to return it for a full refund. Maybe other Autozones do the testing on-site, but I'm glad that I could take the tester home since that meant that I don't have to drive my ailing truck.....

Anyway.....the code is P0302...and the tester diagnosed that as Cylinder 2 misfire.

So; if you were me...what would you do next? BTW...the truck has 75k on it; unknown tune-up history as I am not the original owner.

Thanks, Chuck

 

[SpinnerBait_Nut]

Re: Ford 4.6 Misfire w/CEL on

bad injector, burnt valve, low cylinder presure! bad coil.

 

[fishmen111]

Re: Ford 4.6 Misfire w/CEL on

First, pull the plug and see how it looks. While you have the COP (coil on plug) off, check for spark. My guess is going to be one of those two. Check the connector going to the coil very well.

 

[bruceb58]

Re: Ford 4.6 Misfire w/CEL on

Could even just be a spark plug that failed. I had a misfire and it was caused by the ceramic that lost a chip.

 

[642mx]

Re: Ford 4.6 Misfire w/CEL on

The coil packs interchange. Move the #2 coil pack to the #6 or 7 cylinder and see if the code follows the suspected bad coil. If it does, then the coil pack is bad (which is reaaaallllly common on Furds). I've seen a worn spark plug cause a misfire code before also. Check the plug gap if the code doesn't move, if its out of spec then tune it up.

 

[rogerwa]

Re: Ford 4.6 Misfire w/CEL on

Have the plug and wires changed or do them yourself if brave. It will take you ~3 hours the first time as you need to figure out all the angle to get at the plugs.

I have a 97 expedition with the 4.6l and had this same problem. What happens on the 4.6l is that water can get dowon in the plug hole and short the plug out. My guess is that when you pull out the #2 plug you will find a carbon trace running from the tip over the insulatior to the metalpart. Or you just may need new plugs..

Another hint. Stay away from the high pressure car washes that spray water right into the grill. Thats a great way to get water into the plug holes. BTDT.

 

[SeaKaye12]

Re: Ford 4.6 Misfire w/CEL on

well. I replaced the plugs and wireset. Replaced the fuel filter and the air filter while I was at it.

Essentially; a good old-fashioned tune-up. The old plugs were worn to the point where the gap was about twice as wide as the specs call for. Otherwise didn't look too bad though.

Seems to run fine now. We'll see.

Thanks folks for the help.

Chuck