Stupid question re Defoulers

[junits15]

Yeah the good old days , but that is why I am interested to see what catless people are doing to correct the fuel trim issue that Faosc causes since they aren't able to turn off the rear 02's

Personally I think they're just ignoring it. Its only 10% and from what I'm seeing it seems like its usually 10% richer than it needs to be so the effects are likely not noticeable.

Its probably being compensated for in other ways without being immediately obvious.

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[Robottrainer]

Yeah the good old days , but that is why I am interested to see what catless people are doing to correct the fuel trim issue that Faosc causes since they aren't able to turn off the rear 02's

I think alot just deal with the light. FAOSC turn off on the cat efficiency fault

 

[KBR Stang]

Does anyone know how much hp the stock cats are rated for? I am supercharged with catless longtubes and I'm having the same issue with spacers. If I drill the holes small the o2 and o2 heater won't go ready, if I drill them bigger I get cel for fuel trims. I'm thinking about kooks shorty headers with stock cats. I tried another brand of cats years ago and blew them out within a few months.

 

[2015 Silver GT]

Does anyone know how much hp the stock cats are rated for? I am supercharged with catless longtubes and I'm having the same issue with spacers. If I drill the holes small the o2 and o2 heater won't go ready, if I drill them bigger I get cel for fuel trims. I'm thinking about kooks shorty headers with stock cats. I tried another brand of cats years ago and blew them out within a few months.

How do you expect the o2 sensor to become ready when you’ve removed your cats?

 

[Robottrainer]

Does anyone know how much hp the stock cats are rated for? I am supercharged with catless longtubes and I'm having the same issue with spacers. If I drill the holes small the o2 and o2 heater won't go ready, if I drill them bigger I get cel for fuel trims. I'm thinking about kooks shorty headers with stock cats. I tried another brand of cats years ago and blew them out within a few months.

The problem is thermal shock. Repeated high heat and cool downs in succession. If you want to go oem converter the gt500s are probably your best bet. Used ones are few and far between and their is no guarantee of their condition. New ones are a fortune. The UHO GESIs will live most likey, but they may not provide the conditions necessary to keep the pcm happy and not throw an efficiency code.

 

[KBR Stang]

I'm running my emissions tune and using the spacers. Finding the correct combination with the spacers from what I read was key but I haven't found it yet.

 

[KBR Stang]

I was thinking about aftermarket cats but it seems like a lot of folks with them have the same issue.

 

[robvas]

Are we trying to attribute 10% change in trims due to the rears? That shouldn't be possible

https://www.mustang6g.com/forums/th...-or-not-with-boost.206006/page-4#post-4133619

 

[DougS550]

Getting a set of defoulers to get rid of my CEL. does it really matter which way the bend goes of just whatever is convenient?

My 90-degree bend points inward Parallel, No Issues

 

[KBR Stang]

Are we trying to attribute 10% change in trims due to the rears? That shouldn't be possible

https://www.mustang6g.com/forums/th...-or-not-with-boost.206006/page-4#post-4133619

I always wondered what the "emission" tune actually changes. Does it turn FAOSC on or off? With the emission tune in and the spacers drilled out too much I get fuel trim and misfire codes. I put the regular non emission tune in with the same spacers and everything is great again. The problem with that tune is the monitors never go ready and I live in NY and need them ready for yearly inspection.

 

[junits15]

How do you expect the o2 sensor to become ready when you’ve removed your cats?

It can be done, but good luck finding someone to do it for you.

 

[Robottrainer]

Are we trying to attribute 10% change in trims due to the rears? That shouldn't be possible

https://www.mustang6g.com/forums/th...-or-not-with-boost.206006/page-4#post-4133619

I believe what I see rather than what Im told. I ran the anti foulers with GESI UHO cats. Within three or 4 drive cycles I could see the LTFT going richer. When it hit 12% I reset it. Same thing happened again. Start out fine and then goes out of wack not to.mention the heater and o2 sensors wont set.

At the time I was able to turn off FAOSC, the rear O2 sensors, fault codes, and heaters. I drove the car a month and the LTFT stayed at 3% rich. When I put everything back to stock and turned everything back on, same results. Sits at 3%, stay 0 to 1%. There is something to it.

 

[Robottrainer]

I always wondered what the "emission" tune actually changes. Does it turn FAOSC on or off? With the emission tune in and the spacers drilled out too much I get fuel trim and misfire codes. I put the regular non emission tune in with the same spacers and everything is great again. The problem with that tune is the monitors never go ready and I live in NY and need them ready for yearly inspection.

That's the issue

 

[robvas]

If you're running gesi cats why are you running defoulers?

And think of all the people running defoulers with no issues...

 

[Robottrainer]

If you're running gesi cats why are you running defoulers?

And think of all the people running defoulers with no issues...

Because it threw cat efficiency codes. That's great for them. Not so great for myself and others. Its essentially a crap shoot if aftermarket cats will or wont throw a code.

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