Coil on Plug

[NRA Life Member]

I have a 2014 Limited that has what feels like ignition misfires. It's much worse under a load, say going up hill. Changed spark plugs about 20,000 miles ago. It is NOT throwing any codes but obviously something is clearly wrong. How do I diagnose coil packs with no codes to know what cylinders to look at?

 

[410Fortune]

watch the engine run in the dark
See any blue arching between ignition coils and engine block?
Pull the coils and inspect them
Bad coils will often turn a color around the base like brown or white
After that you can do a ohm resistance test on each coil

For me if I suspect ignition issues on a COP engine that has over 60K-90K miles I will just replace the coils and plugs

many times these coils fail due to water sitting down around the base of the coil (engine washing)
A bit of tune up grease around the boots is required when installing coils to keep the water and dust out of the electrical connections
Cheap coils are just that, cheap and should be avoided

 

[NRA Life Member]

So, I ohm out all coil packs. 4 of them are 16 Mo and 2 are 14.5 M ohm. Is that enough of a difference to worry about? All spark plugs look perfect in color.

 

[KayGee]

How do I diagnose coil packs with no codes to know what cylinders to look at?

You can use a scan tool to check misfire counts and ignition/air/fuel parameters (static and while driving). May or may not be helpful, but it's a basic troubleshooting step.

Are you sure it's misfires you are feeling and not trans issue/shudder?

 

[NRA Life Member]

Actually, no, I'm not sure it's ignition and not transmission shudder. The "feel' is like other cars I've had when coil packs have gone bad. How would I diagnose the transmission?

 

[Mattax]

For the past 4 years I had power issues with my 2011 Explorer and it would throw an engine flashing light when it happened on the highway when attempting to speed up to pass. Took it into shop and no codes were recorded. this happened 4 more times over the four years until two months ago when the light stayed on and set a code. The dealership found a bad coil pack and replaced it and the spark plug. But it continued to have the power issue. I then replaced all the other 5 coil packs and replaced all 6 plugs at the same time. No more power issues.

 

[NRA Life Member]

OK, so I finally had time to replace all the coil packs and I still have the misfire issue. What else could be causing the misfire. It really happens at light to moderate loads. Still throws no codes. What to check next?

 

[jade97]

Did you change the spark plugs?

Note - apologies, I didn't go back through the thread to check...

 

[NRA Life Member]

That was the first thing I tried about 20,000 miles ago. So, the plugs are a year old and 20K miles. I thought for sure they'd still be good. Originals came out at 90,000 ish miles. All the plugs look like they are burning perfect. I pulled them out to make sure they all looked the same and they do.

 

[Red92lx]

Hello,

Before you try anymore parts I'd invest in a obd2 Wifi scanner that connects to a smart phone.I bought one for 15 bucks on ebay. Then download a scanning app, I used InCarDoc which has a free version will let you check each cylinder for misfires. It will find minor misfires that don't meet the threshold to throw a check engine light. That should help narrow down which cylinder is giving you the problems.

Not sure if this apply's to the 3.5l, but my old truck with a 5.4l would only run decent with a motorcraft cop. I tried aftermarket and they would work for a few days to a few months then start misfiring again. Finally went back to all motorcraft and it's run fine since.

 

[J_C]

Put a scan tool on it that shows live data and look at that while the event happens.

You only told us that it "feels like" something similar to when something else was wrong. Tell us exactly what you feel and observe.

Is it possible you have low fuel pressure?

 

[bigdude2468]

Please let us know what you find out. The way you describe it the "misfire" sounds severe enough that a code should be set. Wonder if it could be fuel injector related or as above fuel pressure.

 

[NRA Life Member]

I've got an ELM327 Bluetooth adapter that I use with the Torque App. I just downloaded In Car Doc and will try it this afternoon. Thank you.

 

[Red92lx]

I've got an ELM327 Bluetooth adapter that I use with the Torque App. I just downloaded In Car Doc and will try it this afternoon. Thank you.

Like another poster mentioned, look at the live data while driving the vehicle. When the problem occurs, the live data will tell you where the misfire is occurring. This should help narrow things down.