Cat delete tune

[drive_55_not]

Hmm, well I haven't heard of this... but logically thinking.... how could it? there's no injectors into the exhaust pipe... putting fuel on hot exhaust would be starting a fire... and the fuel has to go through the cylinders which would mean its already burnt...

Not all fuel is burned and that is how COT works, The tune will dump fuel into the cylinders and the unburned fuel will then cool the CAT's.

I'm not sure if COT protection is an emissions thing, but Your tuner should raise COT temps, or disable it, to prevent it from kicking in.

I ran headers and catless for 18months, the MIL eliminators did not werk for me, Tuner disabled the CEL.


And I know you didn't want thread about loudness, But it will be ..


I see K4 beat me to it ... LOL

Good luck OP ...

./

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[blue5.slow]

These cars use widebands for fueling and operate on lambda not A/F ratio. So will not lean out.


On these cars no.


Yes, this will happen. The ECU uses inferred cat temp and will dump fuel if it thinks the cats are too hot. Not sure if tuners are turning this off or not. Technically it is part of the emissions system.
That said it will not hurt anything to have the fuel dump with no cats present.

It doesn’t affect gas mileage?

 

[cvpstudios]

Not all fuel is burned and that is how COT works, The tune will dump fuel into the cylinders and the unburned fuel will then cool the CAT's.

I'm not sure if COT protection is an emissions thing, but Your tuner should raise COT temps, or disable it, to prevent it from kicking in.

I ran headers and catless for 18months, the MIL eliminators did not werk for me, Tuner disabled the CEL.


And I know you didn't want thread about loudness, But it will be ..


I see K4 beat me to it ... LOL

Good luck OP ...

./

in the old days, extra unburnt fuel (from a carb) is the primary thing that made engines not live past 100k, extra fuel, washes down past rings, degrades oil, causes ring wear and other damage. Ultimately resulting in significantly less engine life.

I can't comprehend where a modern EFI car would self sabotage like that.

About loudness, I was just meaning I'm not trying to start a thread about that when I'm sure there's probably many others already discussing.

(I DO want loud, hence the reason for this type of mod to begin with) And my idea of loud is a lot different than most folks. What a lot of people consider loud is too quiet for me. LOL

 

[WildHorse]

It doesn’t affect gas mileage?

No because it does the same thing with the cats intact. Don't overthink this haha.

 

[K4fxd]

It doesn’t affect gas mileage?

By a small margin. It only happens when you are getting on it.

It won't be noticeable since it was doing it with the cats.

It does cause a performance hit so turning it off MIGHT show up on a drag strip.

I think raising the temp would be a way to "turn it off" and still be able to defend it to the EPA since it has not been "turned" off.

 

[blue5.slow]

These cars use widebands for fueling and operate on lambda not A/F ratio. So will not lean out.


On these cars no.


Yes, this will happen. The ECU uses inferred cat temp and will dump fuel if it thinks the cats are too hot. Not sure if tuners are turning this off or not. Technically it is part of the emissions system.
That said it will not hurt anything to have the fuel dump with no cats present.

I just asked my tuner about it and he said being that my car is NA, it pretty much won’t trigger the fuel dump unless I’m on an open circuit track

 

[K4fxd]

Mine triggered at about 1000 feet. I turned it off.

Do a WOT 1/4 mile if your Lambda or whatever your software calls it goes to .77, COT has been triggered.

 

[drive_55_not]

Mine triggered at about 1000 feet. I turned it off.

Do a WOT 1/4 mile if your Lambda or whatever your software calls it goes to .77, COT has been triggered.

I wish I could see .77 L on My Hellcat. Dodge set the stock COT protection so high or low, it's almost criminal, I've logged it calling for .65 Lambda when it kicks in. And that absolutely kills power.

All I want for Christmas is a 2,85 pulley and a tune ..

As for an O/R exhaust being loud, It's more about the tone. These 'Yote's can sound terrible with the wrong exhaust.

I wish I had removed the exhaust from my 2018, MBRP LT's custom fitted a 3" Flowmaster Outlaw, added helmholtz pipe to kill the drone and a mid mounted 3" Vibrant bullet.

That had a nice deep tone and was NASCAR loud WOT.


.

 

[5.0_Lojos]

These cars use widebands for fueling and operate on lambda not A/F ratio. So will not lean out.


On these cars no.


Yes, this will happen. The ECU uses inferred cat temp and will dump fuel if it thinks the cats are too hot. Not sure if tuners are turning this off or not. Technically it is part of the emissions system.
That said it will not hurt anything to have the fuel dump with no cats present.

Dumping fuel for no reason equals dumping loot $$$ am I right? I rather it not dump if no cats are present....

 

[K4fxd]

Dumping fuel for no reason equals dumping loot $$$ am I right? I rather it not dump if no cats are present....

If your tuner will turn off cat protection. I just said it will not hurt the engine if they won't.

 

[5.0_Lojos]

If your tuner will turn off cat protection. I just said it will not hurt the engine if they won't.

Now that I have you here, finding a "Cat delete kit" is a mere impossibility due to emissions stuff... What are your thoughts on taking it to "Pepitos Custom exhaust shop in Mexico" and having them remove the cats and replace with custom piping? My current concern is the eventual cat meltdown or maybe I am following Alejandro Flores a bit to much 🫣 Not sure I wanna spend $$$ on headers and cost of install. Car came with Magnaflow and h pipe resonator delete which drones like hell. Cat removal for piece of mind (yes) but will the drone/sound go to shit city?

 

[K4fxd]

It will get louder.

If "Pepitos Custom exhaust shop, or your tuner has the ability to tune for no cats you should be fine. There are some concerns about the car using the rear sensors to fine tune the fronts.

If this system is not shut off the widebands will drift due to no or a bogus signal from the rears. How bad? IDK.

It does calibrate using the sensor wire so IDK how far it will drift before it runs a recal. I do know it will drift.

With that system shut off it should be fine.

Normally I'd say to run the pipes but engineermike lost HP using the factory headers and no cats.

Was it a fluke????

Is there some tube design tuning done by ford that used the cats???

Hope I was some help.

 

[engineermike]

Lots of tuning implications when removing cats that most don’t consider. FAOSC and blowthrough effects are two of them. And when my car gained power by installing cats was rather mind-blowing…

 

[WildHorse]

And when my car gained power by installing cats was rather mind-blowing…

You won't gain peak power by adding a restriction to the exhaust flow.

What I noticed with my cat delete w/o tune:

~ Increase in MPG
~ measurable increase in power as compared to my fastest 1/4 mile w/cats.
~ No loss noted below 5k RPM for me.

 

[engineermike]

You won't gain peak power by adding a restriction to the exhaust flow.

Believe me when I say that myself, the dyno operator, and the other two guys in the room were all very surprised when I gained power by adding cats. I dynod the car no cats big pulley, swapped pulley/cooldown, dynod again. Swapped in cats/cooldown dynod again. Never even took the car off the dyno. It gained 15 rwhp and the gains were consistent from 6000 rpm and up. I reflashed it as well with the only change being to turn on FAOSC and fatten it up to protect the cats. Upon data review later, I realized that adding fuel actually had no net effect to lambda since the wbo2’s are affected by blowthrough allowed by low backpressure in the no-cat case. Bottom line: even lambda was the same. I don’t think you’ll find a better comparison.

I understand that adding backpressure will rarely increase power but it’s a fact that in some cases it does. Specifically, backpressure can increase power if you are losing charge air out the exhaust during camshaft overlap. You might be surprised to learn that these boosted coyotes run quite a lot of overlap at wot. My theory is that my setup with no cats, 100% 3” straight-through exhaust and 14 psi boost was losing too much air out the exhaust during overlap and adding cats (even with 2.75” piping) added enough backpressure to aid in charge trapping during overlap.

FWIW various fords have a blowthrough calculation in the pcm. This calculates the amount of air that bypasses the chamber in order to determine how much error is induced in the widebands. This logic is disabled on the coyote unless you have a Roush cal. So between the blowthrough effects and erroneous or lack of FAOSC I would say that most performance effects of cat deletes are due to inaccurate fuel ratio control.

Attached is the 3 dyno pulls from that day. Dark blue is with cats, gray is no cats.

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