2012 SD Gas - Bought this in Feb (129k miles). and got it for a great deal. 2 different mechanics and a super experienced exhaust guy I trust said that it def needed a cat on drivers side. It had a P0430 code and a knock sensor code, which may or may not have been related to the bad cat as it was on the same side. Also, had to replace the vapor canister as it was fully clogged big time. (Only mentioning because of potential EGR issues). The drivers side exhaust manifold had to be replaced as well, there was a crack. Exhaust guy said this was probably like this for a long time and one of the most likely reasons for the cat damage,.

Had him replace both cats (was only $50 more to get both, so figured why not), exhaust manifold, replaced all 16 plugs which had never been replaced it seems, and B1S2 O2 sensor that was also bad.

Everything has been fine since then. Codes all went away, power is good, no issues at all. Though mileage is a bit less than expected. I am not towing anything, mostly highway miles and getting around 8-9. I get that is close, but still think it should be a little better.

I am about 1,000 miles into this repair. I happened to be towing for the first time since I got the truck (just a 5x8 come along and bed loaded with items we are moving out of storage, so nothing crazy. Oddly, as I was hooking the trailer up, I did have the thought that the exhaust did smell a little rich but thought, eh, this is my first Ford and my first SD, so maybe that is normal for such a truck. After a few trips over a couple of days moving items, I was returning the trailer to my father in law and lo and behold as I was pulling in, I noticed that the CEL was on.

Pulled out my Forscan tablet, hooked it up, and WTF - P0430...again! I am at a loss because other than the rich smell, I have no symptoms of anything else.

No power loss
No smoke, literally none at all, not even just a puff on start-up
No other codes
No misfires felt (but no CEL thrown)
No oil consumption
No coolant loss
Normal operating temps

I have only done a very preliminary monitor of the sensors, but nothing looks majorly amiss. There is some movement of the B2S2 O2 sensor, but it certainly isn't jumping dramatically nor tracking with the B2S1 O2 sensor.

I reset the CEL and it has stayed off, but I do see it in pending faults so it detected the same issue again. Whatever it is. I would imagine that if a cat was getting borked in just 1000 miles, I'd certainly be seeing some other pretty significant symptoms elsewhere. Am I off on thinking that?

Any ideas or suggestions here?

 

Aftermarket cats? They don't last long if so.

Non-foulers work wonders if you want to go that way

 

No, they are OEM. I was sort of thinking what you mentioned. I am not in CA or NY and I don't have any other problems to speak of. Hell, with all the theft going on, I should have just took them off and left them off. I get it, bad environmentalist I am. Just saying.

I think I'll try to swap the after cat sensors (I think they are the same), reset the code and see if it switches sides. Best case scenario really. Change the o2 sensor and be done. If still on the same side, I may try to make sure my injectors aren't sticking even a little. Sans an additional symptoms, I may just go the non foulers and ride off I to the sunset.

Appreciate the response.

Mike

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That mileage seems a bit rough using a online converter of mpg to l/100km. I had a 2011 f350 6.2 Crew cab longbox lariat levelled with 35"s and I would see about 20l/100km on the dash, nothing hand calculated. That truck was cat deleted, as well as the small muffler and tuned on a dyno through a sct. If the converter I used online is accurate it says you are using about 26l/100km, seems real thirsty. My current 2000 f350v10 does better than that with a 6" lift and 35"s as well. If you're smelling fuel and getting that bad of mileage seems like something must be off.

 

Actually yeah I agree 8-9mpg is low. I get 12-14 from southern CO to Denver, so altitude and a couple passes in there. Stock height, 4.30s and 275/70/18

Not that it would necessarily affect mileage specifically, but have you looked for misfire counts?

 

More likely than not, the engine is running rich which has cause the converter to be overwhelmed. Also causes your fuel economy concerns.

Start by examining your short and long term fuel trims to see if they're running skewed. Bet they are... Most likely issues there would include a dirty MAF sensor or a vacuum leak.

Leave the downstream sensors alone, they won't cause your issues.

 

Your mileage is what we get pulling a 16K 5th wheel on the highway so you have a fuel problem. Being there is no codes on that end I'm guessing you have a leaking injector causing unburied fuel to overwhelm the converters.

Denny

 

This very well may be the case. Seems most logical at this point. That being said, my apologies to everyone for misleading information.

I looked more into the mpg and realized I gave incorrect info. I got that info from Forscan without any calibration. Not sure where it gets that info from, but the dash says average is 10.5 so a little more close to normal. I also failed to mentioned I put 295/70R/18 Wildpeak AT3s on it, so there is a small effect there on MPGs as well. So I think it is still a little low, but not as far off as I initially indicated. Still have an issue though that I need to sort out I do plan on doing the more tried and true method of MPG determination by filling up, noting the mileage, driving, then filling up again, divide gallons into miles. I should do that simply to know regardless anyhow.

 

I will check these out today.

As far as the downstream O2 sensors. I know they don't do anything to affect or cause an issue, but I figured an easy way to test for a possibly faulty sensor would be to swap them and see if it starts giving me a P0420 instead. Probably a low chance, but I've seen stranger things.

I'm with you on vacuum leak, but unsure about dirty MAF sensor in this case...if it was this, wouldn't I probably be getting both P0430 and P0420 since it's just one sensor that would affect both?

 

Yeah so if you're at 10.5mpg you're not far from 11 which could be normal depending upon driving style. I tend to have a light foot. I'm not opposed to 5 to 10 over the limit but I'm not an aggressive driver as it virtually never pays off.

Nonetheless I agree look at fuel trims. I honestly don't know if a dirty MAF would trip both sides in reality (I agree it should in theory) but it's easy enough to pull it and clean it.

If you mess with your downstream 02 it's in the top of the cat. Be careful as the bung is just lightly induction welded in there. Tip: next time ask your exhaust guy to weld it in more solidly My mini-saga here (since all your stuff is new it should cooperate):
https://www.ford-trucks.com/forums/1...l#post19650247

 

It depends. You have go look at the fuel trims to get a better picture of what's going on. Might be multiple things.

 

Ok, so I had a little time yesterday sitting in the truck waiting for a storm to pass to do some more diagnosing with Forscan.

To start, I ran a Mode 6 test and there actually are 16 misfires only on 3 and 5 I'm the past 10 driving cycles. Nothing to set codes and the "overall" numbers it gives us 0 so not sure what that's about. Doesn't tell me a ton since that's one on one bank and the other on the other bank.

Watching fuel trims, it actually looks pretty darn good. The STFT on. Both sides are fully in sync and are about -1.25 on average, so it does indicate a bit of a rich condition, but nothing id consider significant in any way. I am not in front of the ta let I use for Forscan. I saved screenshots of the info but can't post them currently. The LTFT was also really good and basically real close to even both sides as well.

Here's the interesting part. So I reset the code about 3 days ago. And it came back night before last. It stayed on for about a day, but as I was pulling into the house late last night, I noticed that it cleared itself! I guess that is at least good news in that it doesn't seem to be the cats, I don't think.

I wonder if towing those few days has anything to do with it? I was towing a come along with a lot of household items, furniture, boxes, etc. Had it on tow haul mode. Code seemed to throw after I towed a few days on tow/haul mode. Then went away after I stopped towing and hauling for a few days.

 

Pull #3 And #5 coil and remove the boot and see if the resistor will come out or if it's laying in there sideways. If the resister opens up the spark will jump around it and eat away the part of the coil that holds the resister upright. The resister times the spark across the chamber for better fuel burn. That could be your misfires and poor fuel mileage. I would also pull the plugs and see if any look like they are running rich.

Denny