Adventures in Truck Repair

 So, Bruce (as my wife and daughter like to call it) the big brown Ford F250 that hauls around us and our travel trailer decided the week before a major trip was the perfect time to through a little tantrum. Not a major one mind you, but just a small wobbler that was a bit of a puzzler too. 

I started noticing just a touch of hesitation and rough running on our way back from church recently. I thought I imagined it or that it was road vibration since we do live in a county that believes road maintenance is for uppity city people. Then, The Queen remarked that it was running rough too, and I had to admit it was not a figment of my imagination. 

Out comes the code reader for a quick diagnostic…or so I thought. 27 codes later, I was left with a case of “Where oh where do I shoot the parts cannon first?” Knock sensors? Please, not that. They are buried in the valley under the intake manifold. EVAP valves and purge lines? Something else not listed in the codes pulled? 

If you guessed something else, give yourself a cookie. 

As I dug into the question of what to fix first, I started ordering some parts. As I dug deeper, I discovered that the mysteries of the Ford 6.2 liter gasser are very nuanced and hold several potential false trails for the unwary traveler. 

Case on point. Coil arcing. 

What is that you might ask?

Modern engines run on ignition coils. Used to be you had a single coil that led to a distributor cap that fed however many spark plugs wires you had for the number of cylinders you had. As engine technology progressed, bright eyed engineers ditched the distributors in favor of direct connections from the ignition coil to the plugs. Then, they decided that wasn’t good enough. So, they made each cylinder have its own individual ignition coil. 

On my truck, there are 8. And they ain’t cheap. If you go to AutoZone, they want $150ish for a Denso coil (which is the OEM manufacturer on my truck). I generally shop at Amazon or Rockauto for parts where I can get the same parts for roughly half what AutoZone wants for them. When I have the time to wait for shipping that is. 

Sorry for the digression, but back to our story. 

On the 6.2 liter V8, the coils eventually start to wear out and can start to arc electricity through the coil boot to the cylinder head. To diagnose this, start your truck up at night or in a dark shop. The darker the better. Be sure to pull your hood down until the hood light goes off. Now, take a spray bottle with water and spritz a little water towards the base of the ignition coils. If you see a tiny little lightning storm under the hood, you have coil arcing and the coil(s) need to be replaced. 

A new coil looks something like this:

Fortunately, Ford engineers didn’t make it too difficult to get to these as they sit on top of the engine with the fuel rail conveniently bent around them to aid in access. 

So, when I did the water spritz test, all was nice and dark until I got to cylinder number 8. For the uninitiated, cylinders are numbered 1 to whatever from the front of the engine to the back and the left to right. The front of the engine is where the water pump is. So, on the 6.2, number 1 is the front cylinder on the passenger side of the engine which makes number 8 dead last in the back on the drivers side. Number 8 lit up brighter than a summer thunderstorm. 

Little known fact. All that voltage leaking out of the coil can play merry hob with your other electric components and sensors and throw false codes. Maybe.

On The Queen’s Navigator with its 5.4 liter 3 valve engine, that would have me mumbling curses to Ford as the position of that motor in that vehicle takes a little bit of contortionism and a fair bit of blind luck and feel to successfully remove and reinstall a coil in the back of the engine. The 6.2, however, required no such foreplay…or so I thought. 

Removing the coil should involve a simple twist and pull to remove in one piece as shown above. When I attempted to perform that simple task on number 8 coil, it promptly disintegrated into two pieces. Not. Happy. Making. 

Fishing out a coil boot from a spark plug well was not high on my to do list, and it took a minute to find the right set of needle nose pliers that would get the right amount grip to size ratio to fit in the limited space to pluck the now junked coil boot out of its hidey hole. 

To add insult to injury, I discovered (much to my dismay) that I had ordered the wrong replacement coil. There is a right side coil and a left side coil. Left side don’t work on the right side and vice versa. Whichever one I ordered, I needed the other. I looked at the description carefully and thought I’d ordered the right one. No such luck. Fortunately, AutoZone (an hour away) had the correct coil in stock for a hefty premium over what I paid for the incorrect one. Grumble. 

Truck purrs like a kitten now though. 

Update: got it out on the road this morning for a quick test drive, reran the codes and, VOILA, the 27 codes are gone changing that one coil. So, moral of the story is don’t assume the codes point to the problem. The codes never even hinted that the coil was bad (which is a P030x code for cylinder misfire). The coil was firing just fine. It was just lighting up pretty much everything including the plug.