High Flow Cats

[Enigma88]

I have recently installed a cold air intake and an aftermarket cat back exhaust. Now I'm thinking about installing a set of high flow cats, at what point should I start thing about having my ECM tuned?

[toilets]

Right after. I have the same set up... HF cats, cat back exhaust and a CAI. I now have a 6 degree knock and the car is in desperate need of a tune because of this set up...

BTW, I just dyno'd the car yesterday and with this set up I was at 392 rwhp.

[The Stig]

You don't *need* to tune after the high flow cats. But your check engine light might come on.

[cab2g]

If you get the right brand of Hi-flow cats you won't get any CEL. Brands such as Solo have engineered their system properly to avoid any CEL. A CAI and high flow cats should not require a tune. Once you start putting on long tube headers, it affects the readings from the o2 sensors too much for the ECU to think that it's in the normal range however. But CAI+HF cats will not throw any codes. The exhaust itself does not matter as there are no sensors behind the o2 sensors connected to the cats.

[Fishdadddy]

If I'm not mistaken, there is a old post regarding this. I believe Ted Jannetty says that the high flow cats with a cold air intake could require a tune due to the changes in air flow?

[cab2g]

Originally Posted by Fishdadddy

If I'm not mistaken, there is a old post regarding this. I believe Ted Jannetty says that the high flow cats with a cold air intake could require a tune due to the changes in air flow?

some CAIs require a tune, some cats require a tune. But I can attest that if you buy two brands that do not require a tune, their combined effect will not require a tune.

CAI Inc CAI + Solo HF cats = no tune

[13 ZL1]

Originally Posted by Fishdadddy

If I'm not mistaken, there is a old post regarding this. I believe Ted Jannetty says that the high flow cats with a cold air intake could require a tune due to the changes in air flow?

That is correct. I had to tune because it was running too lean. You should get a scanner and keep an eye on the fuel trims if you add the hi flows.

[Enigma88]

So correct me if I'm wrong but it sounds like if I don't get a CEL I might not need a tune? How much does altitude play into it? I live at 5900 feet.

[Juiced1]

Originally Posted by Enigma88

So correct me if I'm wrong but it sounds like if I don't get a CEL I might not need a tune? How much does altitude play into it? I live at 5900 feet.

It doesn't require a tune but I would recomend one. If you plan on doing some more mods in the near future you might want to wait it out. You should do a tune if you get the cel or not.

[Fishdadddy]

If you are going to tune it anyway. Just skip the High Flow Cats and get Long Tube Headers.

[Juiced1]

Originally Posted by Fishdadddy

If you are going to tune it anyway. Just skip the High Flow Cats and get Long Tube Headers.

Another good idea. Way more power with headers.

[IndeedSS1]

I have the Vararam cai, VMax TB, and SOLO high flow cats without tuning. My LTFTs are great and AFR at WOT is on the rich side.

But if you are going to tune, I agree with the others, go headers.

[13 ZL1]

Originally Posted by Juiced1

It doesn't require a tune but I would recomend one. If you plan on doing some more mods in the near future you might want to wait it out. You should do a tune if you get the cel or not.

Well that may or may not be true. I didn't expect to need a tune with my mods but I was wrong. You can read about my saga here.

http://www.camaro5.com/forums/showthread.php?t=147113

[IndeedSS1]

Originally Posted by Orange2SSRS

Well that may or may not be true. I didn't expect to need a tune with my mods but I was wrong. You can read about my saga here.

http://www.camaro5.com/forums/showthread.php?t=147113

I remember seeing that thread and your FT's being that far off. That seems like it may have been a rare case. Mine are great without a tune. I should add that if your results are the norm then everyone absolutely needs to scan no matter what the vendor claims about no tuning needed.