O/R X/H-pipe tuning question

Hey all!

I tried using the search function first, maybe not hard enough but I couldn’t find a definitive answer:

If I run any kind of an O/R X or H pipe in my 07 Gt500 with typical modifications (ported 2.3 TVS, ID1000’s, boost-a-pumps) and don’t re-tune my car or use 02 simulators, do I run the risk of damaging anything/messing up AFR/etc?

I don’t mind a CEL on, if that’s all that it’ll do.

Thanks for your help in advance!



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no issues. Just the cel will be on. Rear sensors have nothing to do with AFR. Only to sense catalyst

PM-Performance said:

no issues. Just the cel will be on. Rear sensors have nothing to do with AFR. Only to sense catalyst

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Roger, thanks for your reply!


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Wouldn't you run lean with a OR versus a catted pipe without a retune?

HillbillyHotRod said:

Wouldn't you run lean with a OR versus a catted pipe without a retune?

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Not really. The exhaust shouldn't lean the engine, and the MAF should detect any additional air if it is taken in.

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an h pipe is fine, and x pipe if it works it can cross scavenge and cause odd fueling at idle and lower rpms

details... EFIDynoTuning • View topic - X pipe Tune Adjustments Required

HillbillyHotRod said:

Wouldn't you run lean with a OR versus a catted pipe without a retune?

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Its cats. . . so no.
Dude already sounds like he has a pretty built car. He could confirm with his tuner, but I have never seen removing cats causing a car to run lean

Don't the rear O2 sensors need to be installed regardless of cats to compete the loop?

Harry08 said:

Don't the rear O2 sensors need to be installed regardless of cats to compete the loop?

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No, not at all. You can block the threaded inserts, tie up the sensors, and the car will not care. The rear sensors only detect temperature to gauge the efficiency of the csts.

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Or you can just unplug the sensors. lol. You will get a cel, but if the light doesnt bother you, no big deal.

I see a lot of bad information in this thread, you guys should really look into the post from Shaun at AED regarding the functions of the rear 02 sensors on 11+ cars with wideband fronts, yes they of course monitor the cats but also essentially keep the front widebands accurate as well, being why you should never unplug or remove them completely even if you have no cats. Here is the thread for anyone who actually wants some good rear 02 sensor information

https://www.svtperformance.com/thre...-or-not-the-definitive-answer-inside.1122899/

96gt02 said:

I see a lot of bad information in this thread, you guys should really look into the post from Shaun at AED regarding the functions of the rear 02 sensors on 11+ cars with wideband fronts, yes they of course monitor the cats but also essentially keep the front widebands accurate as well, being why you should never unplug or remove them completely even if you have no cats. Here is the thread for anyone who actually wants some good rear 02 sensor information

https://www.svtperformance.com/thre...-or-not-the-definitive-answer-inside.1122899/

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That being said, I think YOU need to read the actual post more. He has an 07.

PM-Performance said:

That being said, I think YOU need to read the actual post more. He has an 07.

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GOT ME! LOL

96gt02 said:

GOT ME! LOL

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Sorry man, i couldnt resist. lol

By all means I deserved that one lol, I just look like a dick now haha.

96gt02 said:

I see a lot of bad information in this thread, you guys should really look into the post from Shaun at AED regarding the functions of the rear 02 sensors on 11+ cars with wideband fronts, yes they of course monitor the cats but also essentially keep the front widebands accurate as well, being why you should never unplug or remove them completely even if you have no cats. Here is the thread for anyone who actually wants some good rear 02 sensor information

https://www.svtperformance.com/thre...-or-not-the-definitive-answer-inside.1122899/

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I appreciate the info. Im thinking about going the spark plug anti fouler route when its time to go back to off road H. I get the feeling the next revision wont turn off my rear O2's, even if its for off road drag racing. :/

I knew that Lexus/Toyota uses the rear o2 to fine tune the mixture, but was unsure if Ford did the same. Now I know.

Yeah if the CEL bothers you just get non foulers, they work. That way no CEL and you can still pass emissions unless minus a visual inspection.

MelloStang2010 said:

Yeah if the CEL bothers you just get non foulers, they work. That way no CEL and you can still pass emissions unless minus a visual inspection.

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Love living in Nebraska, where there’s no emissions testing. Now if only it would stop snowing here!! :/


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Slattdaddy said:

Love living in Nebraska, where there’s no emissions testing. Now if only it would stop snowing here!! :/


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Not to mention all the sweet nectar you have growing in them thar fields.

..