cartdodd
Active member
- Thread starter
- #1
I experienced a seemingly random and inconsistent misfire for a few weeks, and it took the dealer a couple of weeks to sort out. It has been fixed, and I wanted to share my experience, and the solution.
TLDR; Random misfire caused by wiring short due to coil pack power being worn by adjacent hose clamp and shorting out under the right conditions.
Just for the context, I have had the truck for right at 1 year (6/20/24) at the point of deciding to take it into the dealer. I had only put just under 12k miles on it, about 11,700 (which may be the slowest driving year ever for me).
Over time, starting about 3 months ago, I started to experience this super random, fairly aggressive thumping. I assumed it was the transmission. It happened at a very specific window, about 55-60 mph and under ever so slight throttle, enough to accelerate but not enough to downshift. It felt like some sort of hit or contact, a decent thump that you could really feel through the whole truck. It started as just a single hit/thump. With a little more throttle, it would downshift and jump the rpm normally, and then seem totally fine. Over time, if I was going up a slight incline and holding throttle, it would start to do this hit/thump repeatedly 2, 3, 4, even 5 times in row, about 1 second apart. I would have to add throttle to get it to downshift just to get passed the thumping, even if it meant speeding up too much and then slowing back down. There were just some cases were the right amount of throttle to hold speed would be right in this range of thumping. Started as something rare and weird, and just became a really obnoxious issue.
Once it finally got to a point of being consistent, not random, very intrusive, and very repeatable, I figured it wasn't something that I could wait any longer to deal with (I live about an hour from my dealership). Based on my experience and the phone conversation with the service dept, I assumed it was trans related. So I took it in for trans check, and the trans tech drove it, was able to diagnose it was actually a misfire. He did a full day of work up. Swapping spark plugs, trading coil packs to different cylinders, checking fuel injectors, and the misfire never changed cylinders or anything of that sort to point to a problem. So I got rescheduled to come back the following week for a specific tech to go further into it.
That first check took one day and I went home with the truck. The second visit took 2.5 weeks. To credit the dealership and team, they drove it 150 miles, tried tons of stuff, took data logs, and everything they could think of, short of just starting to take it all apart to search. The data logs were minimally sufficient to help (and they sent or tried to send the limited logs to ford) but this misfire wasn't happening with a frequency that the data logs captured repetitively or consistently. Even when you could "make" it happen in the right conditions, it wasn't every rotation and it didn't happen every time to log it as more than an anomaly.
The end result actually came from none of the work-up, which I know had to be frustrating to all those who worked on it. The answer came from a response from Ford stating another dealer somewhere had just dealt with a similarly bizarre situation. They found where a specific wire bundle in a specific spot was routed next to a hose clamp, which had rubbed a coil pack power wire down until it was shorting, in the right conditions. Sure enough, my truck had the same thing. Not once was it enough to throw a code or a check engine light at me about a misfire, but a little wiring issue sure caused a lot of headache! They got it fixed in 2-3 hours once they knew where to look...
TLDR; Random misfire caused by wiring short due to coil pack power being worn by adjacent hose clamp and shorting out under the right conditions.
Just for the context, I have had the truck for right at 1 year (6/20/24) at the point of deciding to take it into the dealer. I had only put just under 12k miles on it, about 11,700 (which may be the slowest driving year ever for me).
Over time, starting about 3 months ago, I started to experience this super random, fairly aggressive thumping. I assumed it was the transmission. It happened at a very specific window, about 55-60 mph and under ever so slight throttle, enough to accelerate but not enough to downshift. It felt like some sort of hit or contact, a decent thump that you could really feel through the whole truck. It started as just a single hit/thump. With a little more throttle, it would downshift and jump the rpm normally, and then seem totally fine. Over time, if I was going up a slight incline and holding throttle, it would start to do this hit/thump repeatedly 2, 3, 4, even 5 times in row, about 1 second apart. I would have to add throttle to get it to downshift just to get passed the thumping, even if it meant speeding up too much and then slowing back down. There were just some cases were the right amount of throttle to hold speed would be right in this range of thumping. Started as something rare and weird, and just became a really obnoxious issue.
Once it finally got to a point of being consistent, not random, very intrusive, and very repeatable, I figured it wasn't something that I could wait any longer to deal with (I live about an hour from my dealership). Based on my experience and the phone conversation with the service dept, I assumed it was trans related. So I took it in for trans check, and the trans tech drove it, was able to diagnose it was actually a misfire. He did a full day of work up. Swapping spark plugs, trading coil packs to different cylinders, checking fuel injectors, and the misfire never changed cylinders or anything of that sort to point to a problem. So I got rescheduled to come back the following week for a specific tech to go further into it.
That first check took one day and I went home with the truck. The second visit took 2.5 weeks. To credit the dealership and team, they drove it 150 miles, tried tons of stuff, took data logs, and everything they could think of, short of just starting to take it all apart to search. The data logs were minimally sufficient to help (and they sent or tried to send the limited logs to ford) but this misfire wasn't happening with a frequency that the data logs captured repetitively or consistently. Even when you could "make" it happen in the right conditions, it wasn't every rotation and it didn't happen every time to log it as more than an anomaly.
The end result actually came from none of the work-up, which I know had to be frustrating to all those who worked on it. The answer came from a response from Ford stating another dealer somewhere had just dealt with a similarly bizarre situation. They found where a specific wire bundle in a specific spot was routed next to a hose clamp, which had rubbed a coil pack power wire down until it was shorting, in the right conditions. Sure enough, my truck had the same thing. Not once was it enough to throw a code or a check engine light at me about a misfire, but a little wiring issue sure caused a lot of headache! They got it fixed in 2-3 hours once they knew where to look...
Sponsored
