Question on JB4 / Decat Limp mode ?

[Haz.Supra]

Quick Question - Hopefully this is the right place to put this...


Can a JB4 stop the supra going into Limp mode if you were to install a catless downpipe ?

Further Question... Does the Supra even go into Limp Mode with a Decat ?

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[jtsang25]

Quick Question - Hopefully this is the right place to put this...


Can a JB4 stop the supra going into Limp mode if you were to install a catless downpipe ?

Further Question... Does the Supra even go into Limp Mode with a Decat ?

You can run catless without a tune. You'll get a CEL. jb4 can clear it but I think it still comes back. Someone correct me if I'm wrong.

 

[Haz.Supra]

You can run catless without a tune. You'll get a CEL. jb4 can clear it but I think it still comes back. Someone correct me if I'm wrong.

Does a CEL result in Limp mode or does it just light the dash up like xmas

 

[aksprite]

This is from personal experience. Running a catless downpipe with no tune is not an issue except for rare moments of high overboost. In my case, I engaged in a small pull and right around 120 the car went into limp mode. It was late at night and a little colder than usual. I did have a Jb4 but it was on map zero (stock map). I scanned the codes with my Jb4 and it stated my boost pressure was too high. (120208). This issue is much more prevalent in the Subaru community and a little in the N54/N55 community. Don't let this scare you as it really is rare. Jb4 prevents this by tricking your ECU into believing the car is never above stock psi. As for the CEL, it does not trigger limp mode, you'll just lose the whole function of a check engine light since its always going to be on. Some people have had luck with certain catless downpipes that come with a o2 bypass of some sort. I believe they're made by Armytrix.

 

[Jesse DaBears]

No issues. The only reason why you would is from an pverboost situation. If so lower duty cycle.

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