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Discussion Starter #1 (Edited)
Hey everyone.

First post here after following for awhile, but I hoped to find some advice for an issue I'm unsure how to start with. Heres the full story to answer any questions and draw the full picture of what might be going on.

At about 130k I had to have my Catalytic converter replaced after it started throwing cat codes and acting a lot like the engine was choking, like a clogged cat supposedly should. That was followed by an exhaust scent overwhelming the cabin at 4k and above at speed, me assuming the exhaust had nowhere to go. Of course shortly after that I went and got the manicat changed, and the issues resolved for several months so it seemed. However, about 2 months ago I started getting cat Bank 1 failing codes again. Headed straight back to the shop that installed it, who investigated and stated that its likely just the sensor not recognizing the non-OEM part, and being overly sensitive. It is not running like as bad as it used to pre-cat change, and does not bog down or anything, runs crisp and clean, at speed or not. It did not seem like a cause for alarm. Recently though it started smelling awful (like bad deisel), and my fuel economy appeared to begin dropping slightly. This grew over time until I took it back to that shop, thinking this cat is clogged again, but after passing a flow test they're noticing it is running very rich. To the point that standing behind my exhaust burns your eyes and you can very clearly smell the gas in the air, combined with the half-milimeter of soot in my pipe. Shop said this is the kind of issue at my mileage its better just to drive out rather than money-pit goose chase the issue, and that the second cat should last the abuse longer than the car. Not so sure I believe that, and I'd like to try fixing it. The car is currently only throwing cat bank codes and not engine running rich codes yet, but Ill check again soon with my own OBD2 and confirm along with engine codes to post here.

That said, my thought with what knowledge I have is to try cleaning the MAF, replacing the o2 sensors (no record of having been changed) and changing the sparkplugs (no record of having been changed, need to check them tonight) and run some seafoam through it. I'm currently "in line" for the Fuel Tank recall I'm not sure if will have an effect on this at all, whether being the cause or this issue may be resolved or spotted as a result of the work Ford may do. I've been 3 months on since recieving my acknowledgement letter however and haven't been called to the dealer yet, and I dont know if I want to keep banking on that. Any recommendations or words of knowledge on this situation? Is this a common issue I just haven't read about yet? How awful is it really driving on this? Performance seems okay other than smell and fuel economy.

Thanks. [idea]

TL;DR car is running really rich after an aftermarket cat replacement, dunno if o2's and sparkies/MAF or if I should wait to see if fuel tank recall has effect.
 

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If the catalytic converter was doing it's job it would not smell like that.
OK on to the next point about running rich. Make sure you have a clean air filter, go ahead and clean the MAF sensor, replace your spark plugs, go ahead and change the O2 sensor that is before the cat. I'm not one for throwing parts at a car but without reading the live data on what the O2 sensor is reading it's hard to say exactly what to do.
Also what may be wrong with your car has probably killed the replacement catalytic converter. Even if your car was running rich if it was working correctly it should burn up the excess gasoline to prevent that smell.


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Discussion Starter #3 (Edited)
You really think it already killed it again? Really wanting to go back to that shop and demand they match their warranty, but not sure if I should try these first and see if it has any effect. Despite it only being months old, I could imagine this much fuel dumping burning it fast.


If for whatever reason all that doesnt work out Indiana doesnt do emmissions testing..been eyeballing just pulling the cat and piping it lmao
nothing like a fun gurgle and pop after eventually cat back replacement.
 

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You really think it already killed it again? Really wanting to go back to that shop and demand they match their warranty, but not sure if I should try these first and see if it has any effect. Despite it only being months old, I could imagine this much fuel dumping burning it fast.
Catalytic converters are generally murdered, meaning that what is wrong with the car is why it's dying. You would not have that smell if it was working correctly, but you need to fix what is killing it first. You could kill one in a day if you wanted.

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Discussion Starter #5
Catalytic converters are generally murdered, meaning that what is wrong with the car is why it's dying. You would not have that smell if it was working correctly, but you need to fix what is killing it first. You could kill one in a day if you wanted.

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Okay, thank you. I dont think o2's are very expensive nor hard to replace..so I'll throw all this at this week and see if theres any change, then head to that shop and make them replace the cat again if I can.
 

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Okay, thank you. I dont think o2's are very expensive nor hard to replace..so I'll throw all this at this week and see if theres any change, then head to that shop and make them replace the cat again if I can.
You only really need to replace the upstream O2 sensor at this point it's the one that tells the car to adjust the air fuel ratio. The downstream O2 sensor only reports the efficiency of the catalytic converter.

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The cat IS working and super overtime when you smell that smell, it is the smell of overrich from an engine issue. What that turns into once it hits the cat. The smell tells you the cat is way overloaded and next thing up is a dead cat maybe in minutes if the rich is not stopped and quick.

ALL cats make that smell if overloaded with fuel and your key to it. They don't smell in normal running because most of the HC is burned before hitting the cat which realworld working right should only be burning maybe 7-10% max or what is left after engine gets through burning what it can. Cats were never designed to burn 100% of all emissions, only a small part leftover in normal running. If you try to burn more than that minimum they die, end of story. Normal they go to 1500-2000 degrees, running too rich the temps spike way over that, melted metal territory. Even ceramics melt there.

Once you drive long enough with that heavy smell the smell will begin to die off and THEN ONLY your evidence the cat has died and probably now clogged due to melting of the matrix inside, what happens when you feed too much raw unburned fuel to one.

'If the catalytic converter was doing it's job it would not smell like that.'

NO. The exact opposite. It is a sure sign the cat is working much harder than normal.

If car has the purge valve/fuel tank issue then YES that can ruin cats.
 

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Discussion Starter #9
Well, I started the seafoam last night and bought MAF cleaner and new iridium plugs. Will change those tonight and was able to schedule the cannister purge valve recall work with Ford on monday! So after that, I'll see how bad the issue is and see about going about replacing that upstream o2. Part is about $71 so I wont if I don't need to. Muffler shop said if I fix the A/Fr issue and it ruined the cat, they'll replace it under warranty! so happy man here.
 
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