Ford 5.4 litre question

[Bugsinrugs]

I have a 98 expedition that just started having a problem. It started as a miss under load at around 2000 rpm. It has gotten worse and it misses all the time now,even at idle. Starts fine and runs good until it warms up. My thought is the coil on plugs. Also, it won't throw a check engine light.
Any input would be greatly appreciated.

[rick-l]

get an OBDII scanner

[Bugsinrugs]

I have one and it is not throwing a code. I edited my original post. Sorry.

[stevej37]

I believe there was a thread about 2 weeks ago on this same size engine. They mentioned the problem that the triton engine has with loose spark plugs that will eventually be blown out with the threads. I would first check to see if any had started backing out. Hope this might help.

[Bugsinrugs]

Originally Posted by stevej37

I believe there was a thread about 2 weeks ago on this same size engine. They mentioned the problem that the triton engine has with loose spark plugs that will eventually be blown out with the threads. I would first check to see if any had started backing out. Hope this might help.

Yes, I will check. Funny that when the vehicle had about 20,000 miles on it it blew a plug. The dealer kept it for two months. Of course we got a loaner and they extended the warranty to 100,000 miles. Long since past.

[John Rogers]

Depending on the code reader, there may not be any showing up? I have the extended (Ford and GM vehicles) of Auto Enginuity and before I got the extened versions nothing showed up. Also it only showed about 150 sensors and now it shows about 17,500 check points including chassis, brakes, steering and transmission. If you were in the San Diego area I could plug it in and see what is really going on.

[fastfredracing]

I think some of those older fords do not support missfire data, so it can be hard to pinpoint the miss until it pops a code and turns on the check engine light. I can sometimes enter data through obd11 generic and view the missfire data.
If it is missfiring all the time, even at idle, you can find it the good old fashioned way by unplugging one coil at a time until you find the one that does not lower the idle when you unplug it.
My guess is that it will be a cop , and more likely than not need plugs. Good luck

[fastfredracing]

When they spit a plug out, you will know it, it gets loud!

[stevej37]

If it is a plug blowout problem, there is a cheap fix that is available. I read that Ford triton engines didn't have as many plug threads as needed. The $35 fix includes a threaded adapter that will hold a smaller plug (included) if needed.

[Bugsinrugs]

Originally Posted by fastfredracing

I think some of those older fords do not support missfire data, so it can be hard to pinpoint the miss until it pops a code and turns on the check engine light. I can sometimes enter data through obd11 generic and view the missfire data.
If it is missfiring all the time, even at idle, you can find it the good old fashioned way by unplugging one coil at a time until you find the one that does not lower the idle when you unplug it.
My guess is that it will be a cop , and more likely than not need plugs. Good luck

Every thread I have found points to the COP. Trouble is without a code to pinpoint the cylinder I have to buy 8 coils. I guess worst case scenario is replace all plugs and coils.
Thanks for the input.

[Nostril Cheese]

Auto Enginuity sucks. Get a real scanner on there and check for bad coil packs.

[aigel]

I had such symptoms when my head gasket went on the 4.6 in my 97 F150. Only once the truck was warm did the cooling system build enough pressure to push coolant into the cylinder.

That said, mine did throw a code and CEL. The CEL blinks when there is a miss. I have no doubt a 5.4 has the same functionality in 98.

My bet is also ignition. What I would do is buy one or two coilpacks and start switching out one cylinder at a time until you find the bad one. What I mean is not to buy 8 but just one or 2 and move them through until your replaced the bum one.

G

[Bugsinrugs]

Originally Posted by aigel

I had such symptoms when my head gasket went on the 4.6 in my 97 F150. Only once the truck was warm did the cooling system build enough pressure to push coolant into the cylinder.

That said, mine did throw a code and CEL. The CEL blinks when there is a miss. I have no doubt a 5.4 has the same functionality in 98.

My bet is also ignition. What I would do is buy one or two coilpacks and start switching out one cylinder at a time until you find the bad one. What I mean is not to buy 8 but just one or 2 and move them through until your replaced the bum one.

G

Would you start easiest first? Probably yes

[1990C4S]

You have a COP issue. I would bet $100 on it.

[aigel]

Originally Posted by Bugsinrugs

Would you start easiest first? Probably yes

No, I'd pull both heads and have a look!

Of course, easiest first. I think my suggestion to buy one coil and put it on each cylinder at a time is better than what anyone else had to offer to date on this thread. I just had to tell the cylinder head gasket story first - sorry!

G

[yetibone]

The coils are kinda expensive when you consider replacing all of them in one sitting.

Ford's misfire monitors on the modular engines are notoriously lacking in sensitivity, so the MIL doesn't come on right away, and sometimes it doesn't come on at all, even with a dead skip.

Go with Fred's advise, and unplug coils one at a time with the engine running, and find out which one does not affect the idle when it's disconnected.

[june82000]

Figure out why you are getting a misfire code. If more than one misfire (especially if several) then probably not coils.I've seen a bad maf throw all 6 coil misfires on a 6 cyl. Even my $90 scanner from HF tells which cylinder is misfiring. Shouldn't be hard to figure out.

Sent from my ADR6425LVW using Tapatalk

[1990C4S]

Originally Posted by june82000

Figure out why you are getting a misfire code. If more than one misfire (especially if several) then probably not coils.I've seen a bad maf throw all 6 coil misfires on a 6 cyl. Even my $90 scanner from HF tells which cylinder is misfiring. Shouldn't be hard to figure out.

Sent from my ADR6425LVW using Tapatalk

He does NOT have a fault code, how can the scanner tell him where the misfire is?

These engine are notorious for bad COP's. Do as suggested and buy one COP if you still don't have a code.

It seems very odd that the check engine light is not flashing by the way, misfires dump raw fuel into the cat and damage/destroy it.

[MBAtarga]

Our '01 Expedition has had several coils go bad - but every time CEL was thrown as well as the code. We did have the manifold "warp" (plastic/composite) which caused a strong miss regardless of RPM - engine had about 180k on it. I don't recall if this cased a CEL or a code though - but we had a Ford factory trained tech working at a quick-lube type shop replace it.

[rick-l]

Does this version have the boot, spring and I think it is a ferrite cylinder to form an inductor between the coil and plug?

If you take the boot off and see water or corrosion there is your suspect.