Catalytic Converter issue or something deeper?

[Bob Sheets]

Hey Guys,

I have a 2012 Expedition EL Limited 5.4. The wife was complaining about hesitation,rough idling and a flashing engine light.

I've had this vehicle 3 years and had never changed the plugs,so I did so....and am thankful I did because they were worn out!
So the next day, wife drove around town,no issues(Monday last week). Tuesday, her job took her further out and had the same issues but worse.

I have one of those FIXD code readers and upon scan,told me the #5 and #4 cylinders was misfire. Changed those coils out.

Still have same issues. Traveling the interstate to get home yesterday, any type of grade the engine would miss,car would "buck"...level road,where you can cruise, things would settle down.

I have read that a clogged converter could be the cause of these issues.

Any ideas?

 

[Yosemite Sam]

Hey Guys,

I have a 2012 Expedition EL Limited 5.4. The wife was complaining about hesitation,rough idling and a flashing engine light.

I've had this vehicle 3 years and had never changed the plugs,so I did so....and am thankful I did because they were worn out!
So the next day, wife drove around town,no issues(Monday last week). Tuesday, her job took her further out and had the same issues but worse.

I have one of those FIXD code readers and upon scan,told me the #5 and #4 cylinders was misfire. Changed those coils out.

Still have same issues. Traveling the interstate to get home yesterday, any type of grade the engine would miss,car would "buck"...level road,where you can cruise, things would settle down.

I have read that a clogged converter could be the cause of these issues.

Any ideas?

I'm not a mechanic and I'm a total neophyte to Forscan but the first thing I would do is check ALL the plugs to be sure they
weren't loose in the hole. Secondly I would check with your "code reader" again to be sure there weren't some other
cylinders misfiring and if that didn't prove out I'd become very familiar with Forscan. It can show you, in real time, exactly
what the temperatures are on your cats....if there is an obvious difference in the temperatures with your car running then I
would suspect you had a cat plugging up.....but like I said: I'm not a mechanic and YMMV.....

 

[Motorcity muscle]

My '07 had a misfire when I purchased it used, swapped out one coil myself but apparently it was driven like that for to long by the previous owner. Had to replace the cat on the side of the misfire, luckily the dealer repaired it as good will.

 

[Trainmaster]

You may try swapping coils with other cylinders. Unless you used OEM coils, it's possible that they are bad out of the box, especially if they were $10 China junk from a chain parts store.

What's the mileage on that truck?

 

[Bob Sheets]

What's the mileage on that truck?

148k.

Plugs were worn bad and reading here and around the net makes me worried about my converters.

Hopeful to get it to a shop today to get a better scan of things.

For the future, anyone recommend a good scan tool that won't break the bank?

 

[Motorcity muscle]

Not a scan tool but verizon offers a Hum device that plugs into your service port and constantly monitors vehicle. Have had one on my truck for two years or so and sends a text message if an issue pops up. it also tells you if there's hard braking or hard acceleration, good if you have a new driver.

 

[Trainmaster]

Asking a muffler guy if you need a new catalytic converter is like asking a barber if you need a haircut. A miss on two cylinders won't be caused by the exhaust.

 

[Bob Sheets]

I get it Trainmaster. Just that if the plugs were worn out...

So they are supposed to be changed out at 105 k but have been in there for 43k over...wouldn't that do damage to the converter? Or is that not long enough to do damage?

 

[07navi]

I get it Trainmaster. Just that if the plugs were worn out...

So they are supposed to be changed out at 105 k but have been in there for 43k over...wouldn't that do damage to the converter? Or is that not long enough to do damage?

Miss's are what does damage, not bad plugs.........lot's of missing.

 

[Trainmaster]

Now if you were driving it for 50K miles with the plugs missing and the engine light flashing there might be damage to a converter. But as 07 says, a old plug won't hurt anything until it causes a miss for awhile. Even if the converter's toast, it cannot cause a miss which is what your codes are indicating. A defective converter should show a code and should show a deviation in the downstream oxygen sensor output. It would not generate a miss code.

They usually don't go bad, but a persistent miss could be caused by a bad injector, but two would be doubtful. A head gasket problem could also cause adjacent cylinder misses, but your mileage is on the low side for that.

It's time for some good diagnostics at a shop that knows their stuff.

 

[Dustin Gebhardt]

As Train said, some diagnostic work is now warranted. Move the COPs from the offending cylinder(s) and see if the issue follows the COPs. Th pigtail connectors on the COPs are also known to have issues. The rubber rings break and let moisture into the connector. And the plastic locking clip breaks, allowing the pigtail to come loose. You can also move the spark plugs from the offending cylinder(s) and see if the misfire follows the plug. Cylinder 4 and 5 are on different catalytic converter banks, FYI. What are your upstream and downstream O2 sensors reading. The upstream sensors should cycle up and down in voltage. The downstream sensor should mostly stay constant. If it bounces around, then the cat is likely bad. You can also check exhaust temperature at the exhaust manifold and at the front and rear of the cat. If the heat is abnormally high in front of the cat, then the cat might be plugged. You can also check the fuel injectors. Move the ones in Cyl 4 and 5 to a different cylinder and see if the misfire follows.

 

[ChrisRCNY]

I had a misfire that would appear when the engine got hot, and vanish when it cooled down.

Clip on the coil's input wire was broken, and the silicone the police dept mechanic slathered on everything made the seal work really well. Trapped air would expand, push the connector out, misfire a lot until it cooled and reseated.

Fix was to hold my finger on it long enough to leak down, no issues for 6 months now.

 

[Bob Sheets]

Cylinders 4,5 and 8 were misfiring.

Replaced the coils on all three but #8 still misfired. Pulled the plug and it had a hair line crack in the porcelain and basically fell apart when I pulled it out of the socket. Replaced that and everything is smooth.

Now, I have a P0430 bank 2. That's the left side of the engine,correct? And that's a converter,right?

 

[Trainmaster]

It means that the voltage the oxygen sensor is producing is out of its expected range. You should now find a code reader that can read the voltage coming from the sensor. It could be a bad oxygen sensor, a bad converter, bad wiring or an exhaust leak. Real-time charting of the voltage output, along with perhaps a digital thermometer should narrow down the cause.

On our engines, Bank 2 is the left (driver's) side.