97 Ford F-250 4.6L Bad Misfire

[Bobrock2112]

I have a 1997 Ford F-250 4x4 with a 4.6L Engine. It developed a serious misfire with a Flashing Check Engine Light. I brought it to a garage and their “computer” SAID I HAD A SERIOUS Misfire on Cyl 4 and an “odd reading” on cyl 8. They went on to say getting an odd reading on 8 wasn’t unusual as it will try to pick up the slack from #4 misfiring. So, they replaced the plugs in #4 and #8 and started it up. The CEL went right out and it ran smooth. I drove it about 15 miles and it was perfect.

The next day I started it up and it was misfiring again. I spoke in a forum with a Ford Tech. I told him someone said I may have bad compression in #4. The tech said highly unlikely as putting a spark plug in wouldn’t have made it run well for a day. If the compression was bad, it would stay bad and plug wouldn’t do anything.

I am handicapped and can’t afford to keep running to the garage. So, what do you all think my next steps should be?
Replace my Plug Wires? Change the rest of the plugs? Coil Packs?

Standing in front of the truck looking at the engine, I have 2 coil packs…. One on the left side and oone on the right side. Which coil packs control which plugs?

It is more likely to be a bad injector?

Any help would be greatly appreciated.

Bob

 

[DieselTech]

Take it to another garage or even go to Autozone and have the code pulled. The computer doesn't say a seriouse misfire. In terms like that get ready for a rather large bill from a mechanic. I cannot stress the difference between a mechanic and a technician.

Milage?
Exact codes?

Computers dont say seriouse misfire and odd reading...[censored] is an odd reading. Shady shops I swear!! I would be a shops worst nightmare if they tried to pull that with me.

 

[Steve S]

The compter code was cleared? Then after a predetermined series of whatever it realized a problem and put out a code'Turned on the check engine light.

 

[DieselTech]

Is the misfire more when it's at operating temp?

 

[Bobrock2112]

Is the misfire more when it's at operating temp? [/quote

It seems like it's running smooth at an idle. When I give it the gas it's obvious as it is when I start to drive it. It seems about the same, maybe a little worse at operating tempature. But the check engine light doesn't start flashing until it's well into operating tempature. Before that, the CEL is solid on and not flashing.

I sam smell the gas or really rich when I stand by the truck.

 

[DieselTech]

The richness is likely unburnt fuel. It sould to me that we have an ignition issue. Do you have an Ohm meter?

Whats the milage and have you done coils on it.

 

[DieselTech]

#4 and #8 are opposing cylinder that share the same coil on the 97. If it were me ( Kinda know about fords

) I would do new coil and wires. If it's in the budget ALL new plugs. Plugs that are worn or out of gap will toast Ford coils rather quickly.

This will fix it!!

 

[Panzerman]

I would guess it is a coil pack and not spark plugs anyway. Replace the coil pack on number four. Each cylinder should have its own coil pack. I think they started tha in 97-98.

 

[DieselTech]

Originally Posted By: Panzerman
I would guess it is a coil pack and not spark plugs anyway. Replace the coil pack on number four. Each cylinder should have its own coil pack. I think they started tha in 97-98.


No coil on plug( COP ) until mid 99 on 4.6L F150's and 98 in cars. My 99F150 has 2 coils

If he has an ohm meter he can ohm the wires. Coils usually go because of a weaker link in the ignition system that causes them to over work.

 

[JustinH]

Sounds like a bad spark plug, I have had a bunch of these trucks. Are you getting a check engine light that flashes?

That is the sign of a misfire in the f150 of that vintage.

I would replace all the spark plugs and go from there. Autolite platnium/copper or Motorcraft Platnium/Copper plugs are best for this motor.

If that doesn't fix it, then you need a wire set. I only like the Motorcraft wire set for this motor.

This motor does not have COP..

 

[eljefino]

1st post he does say he gets a flashing CEL.

I like the ign wire idea. I wonder, since this car has OHC and deep "tubes" for the spark plugs to hide in, if oil is fouling the ign wire at the boots. When the plugs were changed the oil fell harmlessly into the cylinders. It only built up overnight, being a slow leak. I wouldn't write off the first garage yet, they could be competent at fixing but hard put to explain stuff to the customers.

Also does the problem track humidity/rain? Been nasty yesterday around here for that. Ignition problems get worse usually with wet weather.

 

[Bobrock2112]

WOW! This is the best forum I've been been on! You are all awesomne and I really appreciate you all caring enough to take the time to respond in detail.

So, I have a few things to try. When I get my next infusion of cash O'll do the wites and maybe the coil packs.

I have 110,000 Miles on the truck. When the shop changed the last 2 plugs (Cyl's 4 & 8) they said they were not factory plugs so plugs have been changed in this truck at least once.

Thanks again everyone!

Bob

 

[Nick R]

New coils definitely. Our 03 4.6L was misfiring, rough running no power etc, flashing CEL. We replaced 3 of the coils. There is one for each cylinder on the newer models, not sure about the 97s. But I would bet on the coil packs for sure. You might as well replace the plugs on them while you have them out with either Autolite or Motorcraft double plats.

 

[mechtech2]

Well, sure.
Other ignition components may be faulty, like wires or coils.
A fresh spark plug always helps, as it takes less current to fire.

But this is almost certainly ignition, since the plug fixed it for a while.

 

[MNgopher]

Coil Packs and Wires. No COP's on this vintage of the truck 4.6L engines till late '99. (My '99 F150 (July Build) with the 4.6 still has wires and two coil packs). Similar symptoms once, did a full coil pack, spark plug wire, and spark plug replacement. Problem solved...

 

[Scott_Tucker]

I would suspect it is a spark plug wire. At any rate since you're on a budget it would be a good idea to do them first, and then only if necessary do the coil pack. Misfires on these vehicles are usually in the secondary ignition system.

 

[AdRock]

Check the wires for any signs of spark jumping. If all the wires look good replace both of the coil packs. If the problem persists, replace the wires.

Also, since the plugs have been messed with lately.. If you start hearing a constant ticking like a slight exhaust leak, check all the plugs immediately. The 4.6's have had problems blowing out spark plugs.

 

[punisher]

Originally Posted By: Scott_Tucker
I would suspect it is a spark plug wire.


We are dealing with an older 4.6 so you always suspect wires first. Plug wires have gone through at least 5 revisions. There us a reason for that.

 

[RemedyX]

Check the heater hose above the Number 4 plug. As the hose ages it drips coolant onto the plug wire when the pressure in the cooling system rises. I had this very same problem.

 

[JustinH]

On a 97 f150, the coil pack is a very stout unit. It has 2 coil packs, each one throws spark to 4 cylinders.

I'd put money that the coil pack is FINE. They last forever.

Plugs and wires.