Can't Get Rid of Engine Roughness - Ideas?

[tdfuller]

Greetings fellow Expedition owners/mechanics/stakeholders:

I’ve got a tricky issue with my 2003 EB 5.4L V8. It is one of the trickiest I’ve dealt with in my 20 years of owning it (sole owner). Started in March. I’d be most grateful in someone can spend an extra few minutes to read the details and provide a few ideas.

Is there something my shop(s) and me are missing?

In March started having bucking/missing engine. Assumed I was having another coil pack go out. Coils in the Expedition are flakey. Replaced almost all of them over the 212,000 miles, but been several years since the last coil got replaced. Took it to a shop I’ve been using the last year when the SES light came on in March. They primarily do AC work – which is how I “met them” a year ago when they replaced the clutch and did some AC work on the Expedition. Since then they replaced my intake manifold, central junction box, and fixed a vacuum leak. Not knowing how extensive their diagnostics are beyond just pulling basic codes, I took to them in March when the SES light came on.

So… they did get P0357 but did NOT believe it was any coil. They said it might be internal timing going bad on the engine. Self-stating they do not really like getting in to all the mystery oils, they did change the oil and filter after running BG EPR (Engine Performance Restoration) because they stated they have had positive experiences on other customer vehicles with BG EPR removing sludge and restoring rough running engines. I am not one to skip an oil change in 20 years. But the BG EPR and oil change seemed to work. For about a month, the engine ran smooth.

…Then April came. Back comes the roughness again. So, I did my own BG EPR (two cans) ran for 20 minutes, then had a quick change immediately change the oil/filter. Did not really help much this time. SES light came on and stayed on. My basic $20 Ancel code reader shows same code P0357.

But this time, elected to go a local shop in the city, recommended by another friend, for whom claims they have the expensive $5K plus diagnostic computer. They confirmed P0357. Replaced coil #7 last week. Sent me on my way. Engine then ran GREAT for three days, all the way to and through parking at the airport for a three-day trip. Best three day stretch of engine operation in many weeks.

Flew home three days later, and IMMEDIATELY on startup the engine is running rough again, and the SES light this time starts flashing. The next day – Tuesday May 30 took it back to the same shop that replaced coil #7, after I pulled codes on my Ancel. My cheap Ancel said I had P0303 cylinder #3 misfire. But the shop Tuesday said their $5K+ computer said code P0306 cylinder #6 misfire. They replaced coil #6. All coils BTW replaced with OEM DG508….. They test drove several miles. All good. I drove it home several miles. All good. Then wife drives its several hours later when I am gone. She said the engine SHUT OFF at the intersection near our house sitting at a light. She was able to restart. But the rough running was back.

I got home late Tuesday night. Can confirm it was running rough yet again. My Ancel has no active code, but it is showing a pending code of P0308 cylinder #8 misfire. I drove it several miles with engine missing but otherwise driveable with good power. The engine never cut off on me. The SES light occasionally blinks then turns off. BTW, badgering the shop if their $5K+ computer shows misfires at the cylinder level. Last week they said it showed misfires galore but ONLY on cylinder #7 until coil #7 replaced. Tuesday they said it showed misfires but ONLY on cylinder #6.

… I’ve had to replace in years past two coils at one time, but never three or more… But any guesses as to what is going on…. Bad run of three coils in a very short period? Something else?

BTW, all eight plugs replaced in December 2019 at ~160,000 miles.

Thanks so much,
Todd

 

[tdfuller]

.... Well... maybe it is, yet again the coils. Why does Motorcraft not design a good coil for the Triton! LOL. The shop's expensive $5K+ computer confirmed my $20 Ancel, misfire #8. Coil #8 replaced. And all appears to be well again. Triton running like a champ again and has done so for at least 30+ miles since #8 coil replacement.

In my 26 years of owning Expeditions; six for my '97 and 20 years and counting for this Expedition - 03 5.4L V8... I had to have two coils replaced at once four years ago, but never three in one week and two of those in 24 hours. LOL. New record on speed and number of coils to fail.

 

[BlackCoffee]

The coil is fired by the computer grounding the coil. Check the resistance between the coil and the computer. Also check to see you have the correct voltage at the coil connection. A bad coil will take out the circuit in the computer.

 

[tdfuller]

The coil is fired by the computer grounding the coil. Check the resistance between the coil and the computer. Also check to see you have the correct voltage at the coil connection. A bad coil will take out the circuit in the computer.

Ok thanks BlackCoffee. Great ideas to keep in mind.... So far the Triton 5.4L V8 has been running perfectly since Wednesday May 31st for five days in a row, after the coil was changed for cylinder #8. I was fully ready to blame something else other than a coil, given I had two coils on two successive days, and three coils in a week "needing" to be replaced, although the vehicle sat parked for three of those days after the replacement of the first of those coils.

My "record" for coil replacement is two needed at one time set back in 2019..... It looks like this may top it; three in one week, with the engine running perfectly - reminding me just how poorly engineered Motorcraft coils are for the Triton motor. I wonder if an aftermarket has an improved design. Usually aftermarket parts I have more trouble with than OEM, but if various products I've owned over the years; cars/boats/airplanes, sometimes a third party will improve and make a better design of a widget than OEM.

I also asked my shop about the Power Control Module (PCM). They said that although replacing coils in buckets for a Triton is not uncommon, that having to replace or update software on the PCM for a Triton is rarely needed.

 

[mbtech2003]

I’ve had good luck with Bravex coils from Amazon. Two sets over 3 years old now. No issues. Set of 8

 

[tdfuller]

I’ve had good luck with Bravex coils from Amazon. Two sets over 3 years old now. No issues. Set of 8

Thanks for the tip.... Do you replace your own coils?

 

[BrandonK4204]

.... Well... maybe it is, yet again the coils. Why does Motorcraft not design a good coil for the Triton! LOL. The shop's expensive $5K+ computer confirmed my $20 Ancel, misfire #8. Coil #8 replaced. And all appears to be well again. Triton running like a champ again and has done so for at least 30+ miles since #8 coil replacement.

In my 26 years of owning Expeditions; six for my '97 and 20 years and counting for this Expedition - 03 5.4L V8... I had to have two coils replaced at once four years ago, but never three in one week and two of those in 24 hours. LOL. New record on speed and number of coils to fail.

thank you for saying this, i have an 04 5.4 with 280,000 miles and its starting to run a little rough, its never had any note worthy work on the engine so ill probably start with the coils.

 

[tdfuller]

thank you for saying this, i have an 04 5.4 with 280,000 miles and its starting to run a little rough, its never had any note worthy work on the engine so ill probably start with the coils.

Coil failure can begin in an innocous way.... Meaning the coil may only cause occasional engine stumble until it really deteriorates. If the engine stumble/roughness is mild and infrequent, see if you can wait to the SES light comes on, or better yet, if you can get a $20 Ancel-like handheld computer, see if a pending code is stored which means the computer has not found the problem bad enough and often enough to turn on the light, but waiting several drive cycles to see if the condition goes away. If it does not go away or gets worse, the pending code becomes active and then the SES light on. The SES light blinks if it is bad and very frequent. But the handheld computer, yours, or O'Reilly Auto Parts loaner up the street goes a long way to giving clues. More than half of the time roughness is a failing coil, but not always, if your plugs have less than 100K miles.

 

[GaryH]

Over the course of 30,000 miles from 60k to 90k, I had 3 coils go bad. After the 3rd one, I just went ahead and replaced all of them and the plugs too.

 

[Darrr]

Sorry for a late reply, but I had similar problem with my 04 EB Expedition. Actually same codes. I had P0303, P0306, P0174,P0357. I immediately changed #3 and #6 coils. Like you, Expy ran good for 3 Days then back to having P0303 code. Other codes cleared themselves. I metered the old original coils to find that they were still ok. So I changed out the spark plugs, coil boots and springs. Still had P0303. I visually inspected #3 fuel injector. Looked good until I unplugged the electrical connector and smelled fuel. There was fuel leaking at the fuel injector plug. I replaced the fuel injector. The Expy has been running and idling great. No more codes. Hope this gives you an idea to solving your issue.