Still Missing....5.4L

[ldeane]

Hi all, need some help...but first a little background...

About 2 weeks ago, my engine started performing badly with no power. Check engine light eventually came on and then started flashing. Trip to my mechanic and he said #7 cylinder was misfiring and it needed a new coil. $140, new coil and engine seemed to run fine.

A week later, starts running terrible again, like on a rock road and check engine light comes back on and intermittently flashes. Auto Zone computer says cylinder #8 misfire. Decide to fix it myself, so I buy an Accel coil and replace it on #8. Doesn't fix it and trip back to Autozone shows #7 and #8 misfire. Decided it must be the plugs.

Replaced the drivers side plugs with new motorsport platinum plugs. Now it runs much better...but..

1) When I press the accelerator from idle it hesitates

2) When climbing a hill or under strain, it still is lacking power...almost like it's missing again, but not as bad. Engine with the windows down makes a "chugging" sound like it did when it was misfiring but again it's better than it was. It seems to idle great.


So my question: Is something else going on? I'm going to replace the other 4 plugs this week...could that be the issue...old plugs and new plugs?

Would appreciate any thoughts or ideas.

btw, about 3 months ago, heater core went out...drove it until 2 weeks ago when it started blowing steam on the windshield...replaced the heater core myself...long job but not too bad.

Thanks!

 

[ldeane]

An update: Drove it around this evening and it's still missing pretty bad, especially around 1500 - 2000 RPM under load. Makes the "chugging sound". We live on a mountain and climbing up, the CEL starting blinking but then went off once we leveled out.

 

[ghettoracer]

Mine is kinda doing the same thing still, it had the same issues you described, but couldnt find the culprit yet. Do you get like a little hesitation at 35 mph? Im thinking mine just needs a trans fluid change and filter. But anywho, did you replace #8 with Accel and left the others Motorcraft? Cause if you did that, then thats your problem. Accel COPs have a higher voltage than the Motorcrafts. My advise is to change out the Accel COP for a Motorcraft or generic like Duralast from Autozone. That might fix your issue. And ALWAYS if you change COPs buy the same brand (Motorcraft or generic OE) unless you want to buy Accels you must buy all 8.

 

[bring_em_on]

You can get a set of COP's off of ebay. You'll need either DG508 or DG511s (I don't think there are any others that would be used but double check that). You can get a whole set for anywhere from 80-120 bucks. I wouldn't mix and match. I would replace all plugs and cops and see how it runs. I had the exact same prob and that took care of it.


p.s. You can see my review of Uneek Supply in the "Reviews" board.

 

[ldeane]

Mine is kinda doing the same thing still, it had the same issues you described, but couldnt find the culprit yet. Do you get like a little hesitation at 35 mph?

No, I get hesitation/loss of power all the time. It's worse in the 1500-2000 RPM range.

But anywho, did you replace #8 with Accel and left the others Motorcraft? Cause if you did that, then thats your problem. Accel COPs have a higher voltage than the Motorcrafts. My advise is to change out the Accel COP for a Motorcraft or generic like Duralast from Autozone. That might fix your issue. And ALWAYS if you change COPs buy the same brand (Motorcraft or generic OE) unless you want to buy Accels you must buy all 8.

I wondered about this. The guy at Auto Zone has a F150, 5.4L same year as my expy and he's running a single Accel coil. His ran fine, he even showed it to me. I bought the Accel as it was $10 cheaper than the OEM part.

Why would it work fine in his truck but cause issues in mine?

Heading up to AutoZone here in a minute to see what the new code is since the CEL is now on. Probably the same thing, but we'll see. Guess while I'm there, I'll get a OEM COP...sure couldn't hurt.

 

[ldeane]

You can get a set of COP's off of ebay. You'll need either DG508 or DG511s (I don't think there are any others that would be used but double check that). You can get a whole set for anywhere from 80-120 bucks. I wouldn't mix and match. I would replace all plugs and cops and see how it runs. I had the exact same prob and that took care of it.


p.s. You can see my review of Uneek Supply in the "Reviews" board.

Thanks, I'll check it out.

 

[02Sexpedition]

I had the EXACT same issues your having, however mine was missing on the #1 cylinder. I had to get the intake plenum gasket replaced, #1 coil, #1 and #2 plug. Runs like a champ now! Turns out the cause was the gasket, air was sucking past the plenum. I'd have that looked at/replaced just cuz its a good preventitive maintanence method. plus with 100k + miles on it, its probably cracked

 

[ldeane]

I fixed it!

Not sure what the problem was, but I took it back up to Auto Zone this morning and #7 cylinder was misfiring. My local mechanic had supposedly replaced this one some weeks back, but it either was a bad part or not fixed correctly.

Anyway, I purchased an OEM coil and while in there decided to put another new spark plug in just in case I might have fouled it with the anti-seize grease. Combination of new plug and coil fixed the problem.

Thanks for all of your help and suggestions. @98Sexpedition, I'll definitely look into that. I'm planning to keeping mine for as long as I can.

 

[dano]

Me missing too

I've got a 05 expy. Just turned over 100K. Runs fine most of the time...but every now and again, it acts like it has a miss in it. I was going to wait and change the spark plugs when it really started to run rough. But after hearing the horror stories of the "dreaded event", I'm just scared now.
If I took it to AZ and have them put it on their test thingy would it show anything if there are no idiot lights on? And, in the event that I would take on the job of changing plugs, should I just go ahead and change the coil packs too? One thing I have noticed is that my fuel economy has dropped by like 2mpg. I had just clean up the K&N air filter, and changed the oil and filter and also put in a fuel injector cleaner (Lucas). Didn't seem to help.
thanks for any info.

 

[nvycrmn]

AZ wont be able to tell you what the problem is if there is no lights on. it wont show a code. as for the missing, it sounds like you have a COP going bad. i would almost wait till it throws a code to tell you which one is bad. either that or just go ahead and replace all the plugs and COPs. its probably about due anyways.

 

[fcaselman]

98 ford expidition misfire #4

We have a similar problem, code reader said #4 misfire so we started out by swapping the cop for #1, problem stayed at #4. Next we changed the plugs but that didnt do anything, Then we swapped the injector from #4 with #1 still no luck. We ran a compression check and it came back fine, while we had the cop and plug out we checked to make sure we're getting spark and it was. Used a noid light on the injector and that worked fine as well...
Im out of ideas and if anyone has any i could sure use a bit of help.
Thank you

 

[toms89]

We have a similar problem, code reader said #4 misfire so we started out by swapping the cop for #1, problem stayed at #4. Next we changed the plugs but that didnt do anything, Then we swapped the injector from #4 with #1 still no luck. We ran a compression check and it came back fine, while we had the cop and plug out we checked to make sure we're getting spark and it was. Used a noid light on the injector and that worked fine as well...
Im out of ideas and if anyone has any i could sure use a bit of help.
Thank you

Sounds like your covering your bases. If you swapped out plugs, cops, and injectors that should eliminate them as the cause. But if it is intermittent your other test may not pick it up.

Wiring harness or connector though I have never personally heard of issues here before.

Bad pcm driver.. have heard of this occasionally.

Or possible mechanical issue that didnt show up on your compression test. Weak valve spring, vacuum leak near #4 cylinder, coolant leak near #4 cylinder.... ?!?