99 5.4L

Had a serious misfire on the way back from the coast Saturday. Had no choice but to drive it home (65miles) since there are no businesses between here and there.

CEL finally came on after a good push with the misfire and pointed at cylinder 3.
Got it home and threw a spare cop on it, problem solved.

Thing is, on the trip home I was getting an unbearable sulfur smell in the cab (raw fuel) figured since the misfire was there..

Changed the cop, misfire gone. It's been 2 days worth of driving and I'm still getting the sulfur smell and bad gas mileage.

I know the cats would probably store raw fuel for a little while, but I have put about 60 miles on it (city driving) since the fix and the smell is still just as bad (mostly when coming to a stop or going up a hill)

I have a spare set of low mileage cats that will bolt right on. Should I consider them toast (160k miles) and change them out or hold out and the smell will burn off?

The crappy gas mileage has me thinking they were on their last leg and that raw fuel from the misfire put them to rest

 

Are you sure you don't have a leaky injector?

 

She's drove like a champ since the fix, no CEL since the fix either... Never considered an injector. No smoke on startups.
I knew the cop's were questionable.. They have about Ooo, 35k on them (global) from a few years ago.

I'll do a leak test on the injectors tomorrow after work. And pull the plug to see what it looks like.

Cat's have been pinging a bit in the recent months at shut downs/cool offs. Fuel mileage was still decent so Ive just kept running them.
Part of the reason I think maybe they were on their way out.

 

The F150 Emergency coil repair kit would have came in handy. The deluxe kit, one1/4" drive ratchet, one 2" extension, one 10mm socket, two 8mm sockets, five 7mm sockets, two coil hold down bolts, one set of red wing boot laces and a roll of wrinkle free duct tape.
At this point, disconnect #3 injector. But, never-mind... That's a whole lot of fuel wash which DID ignite by the sounds of things.
Nasty. Yea, the fuel WAS unburnt for a little while lol. That sulfur smell derives solely from the converter. A convertor on fire or one that has been. Tends to linger as well.
Some of this answer depends upon Y pipe arrangement. Mostly, - Lt's or no Lt's. It matters and I'm not sure if your factory or custom. The smell may never go away. What happens. -Misfires can be expensive...So, if a misfire occurs, the unburned fuel and air mixture is pumped by the exhaust stoke into the catalyst, where it washes over the advanced coating on the catalyst honeycomb. The next blast of hot gas then ignites the mixture, driving up the catalyst temperature by as much as 800ºC and causing a marked deterioration in the catalyst, so that severe catalyst damage can occur very quickly. It is for this reason that the Fuel rail turns off after only four seconds on starting if the engine has not fired - it prevents unburned fuel being pumped into the exhaust. For the purpose of OBD there are two types of Misfire - Type A, where a catalyst is considered to be endangered, and Type B, where damage is borderline. You'll never know the difference since it's entirely within the software lol.
Anyway, once that advanced coating has burnt off, they stink as this was the barrier with that, - sort of a force-field you could say. That said, maybe the smell will go away, eventually. There isn't data either way about that in particular. That's all I have to rely on with this part of the subject. However, I would guess not with what I've read in the past. I'd swap in your other set since it's very obvious your current set is damaged, -well, bank one anyway.

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Mileage decrease is an easy one. Once they've been rich, and this is similar x5, your O2's get cooked. How bad, well that depends, but it happens quickly. So common sense might be that the longer this goes on.... In this case, I would replace both up and down stream sensors and I would do them all at the same time. The downs DO NOT just check efficiency. So keeping those updated has it's pluses as well.

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You prob know all this stuff anyway.... So what, just checking?

 

I had an article about cats, it may be stuff you already know, but here is the link.

http://www.aa1car.com/library/converter.htm

Good luck.

 

Man, I thought those days were gone.
I always have tools with me, just about enough to tear this whole thing down. Especially after the motor swap, I thought it would be good to have. On a positive note, Ive never yet had to go back on anything we did and repair or tighten or whatever else. So, in the recent months the little tool box of spare parts and tools has been forgotten and removed.




Ahh, that magical thought. I did consider shutting the injector off, but at that point didnt have a CEL or which cylinder it was. Surprisingly had to push it hard to get it to come on. The idle was so choppy I thought about pulling over and trying to find which cylinder it was by elimination but decided to just get it home. It was a solid misfire, typically bucking, slight loss of power and a low bumpy idle. By the time I got it scanned and knew which cylinder it was, I was only 1/2 mile from home.

I lack a bit of knowledge in the catalyst field. Just getting thoughts to confirm my thoughts really. I understand the basics of the system. Speaking of, I forgot to mention what you brought up, 02's. I believe the downstreams are original, upstreams have been changed due to a failure a year or so back. Some may argue it but after this, I don't mind changing them for peace of mind. Going to have to wait until after Christmas though. Going to calculate actual fuel mileage today and tomorrow. The trip to work yesterday which normally uses up about 1/8th tank round trip (35miles). Used almost 1/4 tank. So it seems I went from about 15-16mpg mixed driving down to 8-10. Funky, truck is running great though. Other than the occasional smell and crap fuel mileage.

I have the stock Y pipe and cats. Replacements have been sitting around since my swap. Ive kept them around waiting for the old to fail and it seems that may have come around. May be a good time for me to split the Y and throw and X pipe in there to compliment the magnapacks.

Thanks for the info, great article. I have an infrared thermometer. I'll try and find it, see what the temps are after a good drive.
Between brew and the article I think it's good to say/confirm that I overheated the cat, washed the 02 out and now I can either sit and wait for a complete failure or just change them out, once I convince my wife I have to do some cutting, install an x pipe and change the tail pipe direction out for better efficiency.

 

I replaced mine after the same issue. I swapped the rear cats and now the front ones are failing and pieces are falling into the rear ones making a clanging sound. I wish I would've just cut them out when I had the chance

 

If your able to weld them back in, you can just hollow them for that "factory look."

 

Never never run a motor with cylnders out for any length of time other than very short time testing if needed.
The cats run at over 600 degrees from the cylinders that are working and will burn raw gas passed through by the cyllinder not fireing.
This raises the cat temps to well ,over 1000 degrees melting the substrate in the front cats plugging the front and rear.
The results is reduced power, poor fuel milege and very often the OX sensors are also burned up and cannot function.
The secondary cost of this from what started as a bad coil/s is huge in comparison.
BTW 1000 degrees is a bright red color the cats will get in addition to a lot of hot smell from the surrounding area getting too hot.
Good luck.

 

Toyz, I had a very similar thing happen to me a week & 1/2 ago when an injector stuck open on my 05. I was roughly 20 mins from my girlfriend's house so I attempted to drive it (misfiring and all) there. Well... least to say I didn't make it there and had to be towed. It was under extended warranty with Ford so I got the injector and oil changed. Got the truck back and darn if I'm having the same issues you are and I'm showing CEL codes. Dealer ordered me a cat and tomorrow they're putting it on for me free of charge. My symptoms were as yours, smelling raw fuel in the cab, sucky fuel mileage, and no power with a pinging noise under the hood (I'm guessing all the back pressure).

Good luck! Expensive fix when ya ain't under warranty

 

Trust me, it wasn't something I wanted to do. When I noticed the misfire I was about 5 miles into a 70 mile trip home where there is no cell service and the only store that used to be half way between the pass closed down last year. It was 50 miles to cell service and by then I just kept on going to get it home the other 15 miles or so. Guess I could have turned around when I noticed it and headed back 5 miles. Had the kids in the truck and running late to get back.



I guess it's a good time to get the exhaust done I have been wanted to.

Coulnd't find my thermometer. I looked today after a good drive and it is not glowing hot.
Still getting poor mileage though and the smell of rotten eggs/sulfur every once in a while (seems to be getting better) The lack of power is gone and all has seemed to be running good since the misfire was fixed.

Thank god I don't have the injector issues you do with that 3v. But I gotcha, no warranty here but luckily a spare set of cats and Y pipe that will bolt on.

 

Changed upstream 02's today
Can't tell yet if my mileage got any better yet but assuming so.
Changed the oil as well (had fuel smell)

 

Yea, I've seen what this looks like dismantled. The upstream converter ignites, catching it on fire. Therefore you have a 2.5" torch feeding the downstream converter. Both converters on that bank get trashed. The downstream has a 2.5" melted section where the pipe enters the converter.

I suspect Toyz will see this once he changes his.

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BTW, side note - Once the O2's are gone, you may not get a DTC and the engine may seem to run fine. BUT, it will not be fueling correctly. I experienced this once when using Borg Warner O2 sensors. Everything seemed fine, but the engine was going thru fuel like crazy. 8 or 9 per gallon at best and that was empty, no load. Swapped in Bosch OEM's and went back up to 16 mpg just like that.

So the O2's health and general make up seems to be very important when it comes to fueling.

 

I hope you caught that in time I didn't think about that earlier, but yea, that can do her in for sure.

Your probably alright, but that may have freaked me out sort of lol. I'd have to compression check to be sure or just worry a little.

 

Another Note: Why headers make a difference. If you run LT's you don't use Bosch O2 sensors because switching becomes very weak. The O2's are so far downstream compared to OEM set up, sometimes the upstream O2's may never light off. And that's why you use Motorcraft sensors over Bosch. Justin @ VMP proved that and posted the graph showing it.

Not that you needed this info Toyz, but quite a few run LT's and its good to know.