Random Misfire Detected

[JustHarsh]

Didn't think I would be posting an issue so quickly. Bought my 2017 Expedition XLT just 4 days ago. Last night on the way home I accelerated hard overtaking another vehicle, and just as I had passed them and back into my lane, lost power, acceleration stuttered and check engine light started to flash. I let up on the throttle and coasted for a bit and the check engine light stopped flashing and I got power back. I was very close to home and made it back without issue.

Pulled the codes today and have various Misfire Detected: P300, P301, P302, P304, P306. Also P420 and P430. So, from reading up here and other places, the misfires could be the plugs or coils, maybe both. Called the dealer I just bought it from and told them the issues.

Now, this is a 2017 with 85k miles and no warranty. Regardless, they sent a tow to bring it back to their shop (over 30 miles away) to diagnose the issue and figure out what to do. The tow showed up today and while the truck was being loaded we noticed something in the muffler. Looked like someone shoved a black wig in the pipe. It was the fiberglass material in the muffler coming out the tail end.

I called my mechanic and he said his game plan would be to change all the plugs and replace the muffler. Clear the codes and see if any more misfires get registered. If they do show up then move to changing out coils on the cylinders that misfire.

So, the dealer got the truck a few hours after talking to my mechanic and what they are doing is changing out all the plugs and installing a new muffler. Should have it back tomorrow.

The wife and I really like this Expy, but she is now questioning if this is going to be a reliable vehicle to take on any trips farther than the grocery store. Thinking about getting the extended warranty the dealership offered 4 days ago. Replacing plugs and coils are fairly simple tasks, but I'm starting to think that a little piece of mind might be worth it.

 

[Trainmaster]

I think you are on the right track. At 85Kmiles it's quite possible that the plugs were never changed and they are due. The original driver may never accelerated hard or just ignored the problem. Changing plugs is regular maintenance.

Coils occasionally fail, and replacing the failed coil with a quality replacement will solve that problem if a miss persists after replacing the plugs.

The Fiberglas you see coming from the muffler is just part of the muffler's silencing element. That happens sometimes, and unless it's making noise I wouldn't bother changing it. The stainless steel of which the OEM mufflers are constructed usually lasts the life of the car, unlike most replacements.

You have a good truck there. No reason to worry. You can go on line to a vendor such as Lombard Ford and buy a Ford extended warranty anytime up to 100,000 miles at a much lower cost than most offer them locally. Just don't wait for a big problem as they send someone to inspect the truck, and it should be running.

 

[Motorcity muscle]

Hate to say this but the P420 & P430 indicate cat problems. With engine having misfires raw fuel gets into the cats and can ruin them. Both cats could need replacement, this may be your best chance to get dealer to repair truck.

 

[JustHarsh]

I have asked if diagnostics can be run on the cats to see if they are damaged. Not sure how far they are willing to go, but never hurts to ask.

So if the cats are damaged and either diags don't tell that story or they are not willing to go that far, what, if any, further damage is done running with damaged cats? Will it cascade and cause issues with other parts?

 

[Motorcity muscle]

Dealer should know that misfires ruin cats. Several test can determine if cats are good, one is with an infrared thermometer, outlet should be hotter than inlet. Cats are expensive so expect some pushback.

 

[JustHarsh]

Dealership called and they did end up testing the CATs. Their tests showed that they were operating as they should and there was also no sign of fuel contamination on the coils or plugs. I know that CATs are a sensitive subject as they are expensive and there is limited stock right now. I'll have to take their word on it and have my own mechanic take a look later this month when he does some fluid changes.

They said that the misfires were happening under 92% load. They told me they did a thorough test drive under hard load to make sure no codes were thrown.

All-in-all, they did all this at their expense when they probably didn't have to. Not sure what the laws are here; if there is any protection within a certain number of days from purchase and major issues occur. Probably not. So, I'm pretty happy they have made, what I would consider, a good attempt to make it right.

Time will tell, but I have a really good mechanic here locally who goes above and beyond, so I'm sure he'll point out any issues that need addressing.

 

[Motorcity muscle]

Hope it works out for you. Did they say how they tested the cats? If the dealer said "no sign of fuel contamination on plug or coil", do not know how fuel would get on coil.

 

[maxxplatinum9137]

Didn't think I would be posting an issue so quickly. Bought my 2017 Expedition XLT just 4 days ago. Last night on the way home I accelerated hard overtaking another vehicle, and just as I had passed them and back into my lane, lost power, acceleration stuttered and check engine light started to flash. I let up on the throttle and coasted for a bit and the check engine light stopped flashing and I got power back. I was very close to home and made it back without issue.

Pulled the codes today and have various Misfire Detected: P300, P301, P302, P304, P306. Also P420 and P430. So, from reading up here and other places, the misfires could be the plugs or coils, maybe both. Called the dealer I just bought it from and told them the issues.

Now, this is a 2017 with 85k miles and no warranty. Regardless, they sent a tow to bring it back to their shop (over 30 miles away) to diagnose the issue and figure out what to do. The tow showed up today and while the truck was being loaded we noticed something in the muffler. Looked like someone shoved a black wig in the pipe. It was the fiberglass material in the muffler coming out the tail end.

I called my mechanic and he said his game plan would be to change all the plugs and replace the muffler. Clear the codes and see if any more misfires get registered. If they do show up then move to changing out coils on the cylinders that misfire.

So, the dealer got the truck a few hours after talking to my mechanic and what they are doing is changing out all the plugs and installing a new muffler. Should have it back tomorrow.

The wife and I really like this Expy, but she is now questioning if this is going to be a reliable vehicle to take on any trips farther than the grocery store. Thinking about getting the extended warranty the dealership offered 4 days ago. Replacing plugs and coils are fairly simple tasks, but I'm starting to think that a little piece of mind might be worth it.

Bit of advise, that’s not a muffler. That’s a resonator. The muffler is mid truck and much longer. If you want it to sound mean as ****, I suggest removing the resonator (the one with fiberglass coming out of it) just cut it off, did this on both my 2016s and they sound really good. No drone or rasp

 

[LokiWolf]

Bit of advise, that’s not a muffler. That’s a resonator. The muffler is mid truck and much longer. If you want it to sound mean as ****, I suggest removing the resonator (the one with fiberglass coming out of it) just cut it off, did this on both my 2016s and they sound really good. No drone or rasp

The 4th Gens have proven otherwise to be loud, and have drone with exhaust changes. Even doing something as simple as removing the "resonator".

 

[LokiWolf]

Didn't think I would be posting an issue so quickly. Bought my 2017 Expedition XLT just 4 days ago. Last night on the way home I accelerated hard overtaking another vehicle, and just as I had passed them and back into my lane, lost power, acceleration stuttered and check engine light started to flash. I let up on the throttle and coasted for a bit and the check engine light stopped flashing and I got power back. I was very close to home and made it back without issue.

Pulled the codes today and have various Misfire Detected: P300, P301, P302, P304, P306. Also P420 and P430. So, from reading up here and other places, the misfires could be the plugs or coils, maybe both. Called the dealer I just bought it from and told them the issues.

Now, this is a 2017 with 85k miles and no warranty. Regardless, they sent a tow to bring it back to their shop (over 30 miles away) to diagnose the issue and figure out what to do. The tow showed up today and while the truck was being loaded we noticed something in the muffler. Looked like someone shoved a black wig in the pipe. It was the fiberglass material in the muffler coming out the tail end.

I called my mechanic and he said his game plan would be to change all the plugs and replace the muffler. Clear the codes and see if any more misfires get registered. If they do show up then move to changing out coils on the cylinders that misfire.

So, the dealer got the truck a few hours after talking to my mechanic and what they are doing is changing out all the plugs and installing a new muffler. Should have it back tomorrow.

The wife and I really like this Expy, but she is now questioning if this is going to be a reliable vehicle to take on any trips farther than the grocery store. Thinking about getting the extended warranty the dealership offered 4 days ago. Replacing plugs and coils are fairly simple tasks, but I'm starting to think that a little piece of mind might be worth it.

Plugs, plugs, plugs....change them and it should take care of your issues.