OBD2 Readiness Monitors with Tune

[Robottrainer]

Either your tuner force pass all emissions checks, or you have to run a spacer. Since your catted, a straight spacer should do the trick. In the offchance it doesnt, buy catted spacers. I run catless headers and never had a cel or issue inspecting with catted extensions. I dont see why you are against the spacers, you put them on and never touch them again, theyre post cat sensors, they dont effect the fuel trims at all, especially if your car thinks the car is operating under catted oxygen levels

My experience was different. I fabbed 3" pipe and GESI UHO cats. It eventually threw efficiency codes. I installed the spacers. Within 10 drive cycles my trims were +10 percent. I could feel the car getting lazy. I did a reset. Car felt great again but eventually went back to being lazy.

I could never get the 02s or heater to set ready. For I test, I was able to turn the rear 02s off and disable FAOSC. The trims came back down close to 0 and stayed there. I eventually gave up and went back to stock, turned everything back on. Everything went green within two drive cycles.

This was on a 2021 with stage 2 Roush supercharger.

I guess your results may vary.

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[Wolfys11]

My experience was different. I fabbed 3" pipe and GESI UHO cats. It eventually threw efficiency codes. I installed the spacers. Within 10 drive cycles my trims were +10 percent. I could feel the car getting lazy. I did a reset. Car felt great again but eventually went back to being lazy.

I could never get the 02s or heater to set ready. For I test, I was able to turn the rear 02s off and disable FAOSC. The trims came back down close to 0 and stayed there. I eventually gave up and went back to stock, turned everything back on. Everything went green within two drive cycles.

This was on a 2021 with stage 2 Roush supercharger.

I guess your results may vary.

When using spacers on high flow cats, very often you have to mess with the length/ opening diameter to adjust flow to o2 sensors

Some cats do more and less burning of exh gas so sometimes you dont fit for a normal extension. They make ones with 90 deg bend, some with replacable different sized cores, some with cat inside them. One of them will make it right, just gotta mess with it a little bit

 

[Robottrainer]

When using spacers on high flow cats, very often you have to mess with the length/ opening diameter to adjust flow to o2 sensors

Some cats do more and less burning of exh gas so sometimes you dont fit for a normal extension. They make ones with 90 deg bend, some with replacable different sized cores, some with cat inside them. One of them will make it right, just gotta mess with it a little bit

Oh I did. You should see my collection. Straight (long and short), mini cat, no cat, J with different pills. Even welded in new bungs closer to the cat outlet. Same results everytime. Everything was ready except O2 and heaters and the trims would drift rich. I didn't believe they would until they did. Can't argue with results.

 

[Wolfys11]

Oh I did. You should see my collection. Straight (long and short), mini cat, no cat, J with different pills. Even welded in new bungs closer to the cat outlet. Same results everytime. Everything was ready except O2 and heaters and the trims would drift rich. I didn't believe they would until they did. Can't argue with results.

Hm, very odd. I know for myself catless with catted extensions works perfectly, no fuel trim issues nor any issues with i/m readiness, i get green lights within 30 miles almost

 

[Robottrainer]

Hm, very odd. I know for myself catless with catted extensions works perfectly, no fuel trim issues nor any issues with i/m readiness, i get green lights within 30 miles almost

What year is yours? Might have something to do with the year and the Roush strategy

 

[Wolfys11]

What year is yours? Might have something to do with the year and the Roush strategy

My ecoboost 2015 previously and my current ess supercharged 2023 both never had issues as catless with catted o2 extensions

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