Hello all - I'm new here, and looking to see if I can get other input from folks who know a lot more about vehicles than I do. I'm an IT Systems Engineer by trade, and only started working on vehicles with our 2005 Toyota Sequoia and now our 2013 Expedition EL. First things first, a background...
We needed a 8 seater to replace the Sequoia (we have 6 kids, it's at 255k miles) and so we found a used 2013 Expedition with 137k miles on it. We bought it from a dealer, and denied the warranty (they wanted nearly $75/month more on a 5 year loan for a 2 year/24k mile warranty. I figured we knew a good mechanic if anything goes wrong. Literally just after we bought it and it went past the 7 day return/exchange policy, we started getting random misfires (blinking CEL) when accelerating fast, like on highway ramps. Additionally, the left side IWE Actuator was bad... but I've since replaced that and it's working great.
We took it to a mechanic, and he said it was spark plugs and coil packs. We replaced those (all with Motorcraft parts), but it actually got way worse. We had a family trip down to Iowa, and it wasn't until we got 50/100 miles on the road when the misfires started happening. It was typically when accelerating up a hill and when it needed to be given a bit more gas. I used a code reader to see Cylinder 4 (typically) and Cylinder 8 (less frequently) were getting misfires. We were already on the road, and found that if we lightly feather the gas, then it didn't misfire nearly at all. We made it to Iowa, and after being down there for a few days and driving back (around 800 miles on the engine) it actually seemed to be doing really well. Then the Wednesday after it all went to hell again.
It typically only starts bucking and the blinking CEL comes on after it's got some type of load, like when going up hill. It will, however, idle rough and you can feel the misfires happening when idle. I've taken the coil packs out on Cyl 4 and 8, cleaned them, blew out the spark plug well, and reseated it with dielectric grease again - didn't seem to help. I didn't remove the spark plug as I didn't have the proper tools at the time and it's a pain in the ass to get back there (rear on passenger side). Recent developments were when my wife took it through a car wash and the blower was blowing on the front grill, it started bucking like mad and misfiring on her. It wasn't until she moved it past the blowers that it calmed down. We've checked the air filter and it seems fine. At this point, we replaced the MAF sensor per the suggestion of a friend.
We've used Seafoam in the gas tank (we had about 4 gallons of gas left and put 2 x 16 oz cans into the tank and ran it to 5 miles to empty) incase something was gunked up, but it made no difference. We tried to use the Seafoam top engine cleaner, coming at it from the top of the air intake, but I don't know this was successful as we found a lot of it in the air intake reservoir near the air filter. My thought is it may have accidentally been spraying down on the tube and accumulated and drained back into the reservoir. I made sure to do it near the throttle valve (down stream from the MAF), but I'm curious if I screwed up somehow. We actually don't remember seeing any smoke/exhaust that was out of the ordinary when I did it. I may try this again and go at it without the air intake connected, spraying it as far back as I can go.
I tried swapping Cylinder 4's fuel injector with Cylinder 1 to see if it was possible it was a fuel injector not providing enough gas, but this made no difference and the misfires still indicate Cylinder 4 and occasionally Cylinder 8.
At this point, I'm not sure where to go next. We're trying to limit the expenses, so we've been focusing on what we can do without replacing parts or taking it in to a mechanic. From my understanding online, we could be looking at a vacuum issue, a compression issue, or some other type of mechanical failure. Any other thoughts on what I can try next?
TLDR; We've replaced Spark Plugs, Coil Packs, a Mass Air Flow sensor, and swapped Cylinder 4 Fuel Injector with Cylinder 1 - all to no avail. Still getting misfires on Cylinder 4, and occasionally on Cylinder 8, when the vehicle is under load, but sometimes at idle as well. Maybe it's my imagination, but it seems like it misfires more frequently when driving with a headwind.
We needed a 8 seater to replace the Sequoia (we have 6 kids, it's at 255k miles) and so we found a used 2013 Expedition with 137k miles on it. We bought it from a dealer, and denied the warranty (they wanted nearly $75/month more on a 5 year loan for a 2 year/24k mile warranty. I figured we knew a good mechanic if anything goes wrong. Literally just after we bought it and it went past the 7 day return/exchange policy, we started getting random misfires (blinking CEL) when accelerating fast, like on highway ramps. Additionally, the left side IWE Actuator was bad... but I've since replaced that and it's working great.
We took it to a mechanic, and he said it was spark plugs and coil packs. We replaced those (all with Motorcraft parts), but it actually got way worse. We had a family trip down to Iowa, and it wasn't until we got 50/100 miles on the road when the misfires started happening. It was typically when accelerating up a hill and when it needed to be given a bit more gas. I used a code reader to see Cylinder 4 (typically) and Cylinder 8 (less frequently) were getting misfires. We were already on the road, and found that if we lightly feather the gas, then it didn't misfire nearly at all. We made it to Iowa, and after being down there for a few days and driving back (around 800 miles on the engine) it actually seemed to be doing really well. Then the Wednesday after it all went to hell again.
It typically only starts bucking and the blinking CEL comes on after it's got some type of load, like when going up hill. It will, however, idle rough and you can feel the misfires happening when idle. I've taken the coil packs out on Cyl 4 and 8, cleaned them, blew out the spark plug well, and reseated it with dielectric grease again - didn't seem to help. I didn't remove the spark plug as I didn't have the proper tools at the time and it's a pain in the ass to get back there (rear on passenger side). Recent developments were when my wife took it through a car wash and the blower was blowing on the front grill, it started bucking like mad and misfiring on her. It wasn't until she moved it past the blowers that it calmed down. We've checked the air filter and it seems fine. At this point, we replaced the MAF sensor per the suggestion of a friend.
We've used Seafoam in the gas tank (we had about 4 gallons of gas left and put 2 x 16 oz cans into the tank and ran it to 5 miles to empty) incase something was gunked up, but it made no difference. We tried to use the Seafoam top engine cleaner, coming at it from the top of the air intake, but I don't know this was successful as we found a lot of it in the air intake reservoir near the air filter. My thought is it may have accidentally been spraying down on the tube and accumulated and drained back into the reservoir. I made sure to do it near the throttle valve (down stream from the MAF), but I'm curious if I screwed up somehow. We actually don't remember seeing any smoke/exhaust that was out of the ordinary when I did it. I may try this again and go at it without the air intake connected, spraying it as far back as I can go.
I tried swapping Cylinder 4's fuel injector with Cylinder 1 to see if it was possible it was a fuel injector not providing enough gas, but this made no difference and the misfires still indicate Cylinder 4 and occasionally Cylinder 8.
At this point, I'm not sure where to go next. We're trying to limit the expenses, so we've been focusing on what we can do without replacing parts or taking it in to a mechanic. From my understanding online, we could be looking at a vacuum issue, a compression issue, or some other type of mechanical failure. Any other thoughts on what I can try next?
TLDR; We've replaced Spark Plugs, Coil Packs, a Mass Air Flow sensor, and swapped Cylinder 4 Fuel Injector with Cylinder 1 - all to no avail. Still getting misfires on Cylinder 4, and occasionally on Cylinder 8, when the vehicle is under load, but sometimes at idle as well. Maybe it's my imagination, but it seems like it misfires more frequently when driving with a headwind.
