Green high flow cats

[Gavros 4 Life]

hey anyone know the word on these? i know they wont throw a code with headers so wouldn't need a tune but do they still cause the car to run lean?

[Gavros 4 Life]

anyone?

[axis]

Where did you read that HFC's make your car run lean? We have LOTS of members running LT's with and without HFC's and no tune, without a problem.

[the_fast_one]

Headers and HF or no cats cause the car to run rich not lean

[Gavros 4 Life]

Originally Posted by axis

Where did you read that HFC's make your car run lean? We have LOTS of members running LT's with and without HFC's and no tune, without a problem.

i thought the usual run around was once you get headers you will need a tune because as according to the post beneath yours it will cause the car to run rich but i thought the car would run lean.

I understand you will def get more out of your simple bolt on's and headers with a tune without causing any issues but i thought without the tune you can come into problems at least thats what i got out of reading various other threads.

[the_fast_one]

I have kooks with no cats and run rich. My CEL is on but no issues after one track day and 500 miles. I am waiting on my cam install etc to tune it..should be two or so more weeks then it will all be done. lots of people have ran headers and HFC with no problems for many miles though. You do leave some hp on the table with out the tune.

[axis]

Originally Posted by the_fast_one

I have kooks with no cats and run rich. My CEL is on but no issues after one track day and 500 miles. I am waiting on my cam install etc to tune it..should be two or so more weeks then it will all be done. lots of people have ran headers and HFC with no problems for many miles though. You do leave some hp on the table with out the tune.

What makes you think you're running rich?

[axis]

Originally Posted by Gavros 4 Life

i thought the usual run around was once you get headers you will need a tune because as according to the post beneath yours it will cause the car to run rich but i thought the car would run lean.

I understand you will def get more out of your simple bolt on's and headers with a tune without causing any issues but i thought without the tune you can come into problems at least thats what i got out of reading various other threads.

You gain more from the tune because they properly tune the car for the added air. Letting the PCM account for the added air isn't as effective as properly tuning for it.

[the_fast_one]

Originally Posted by axis

What makes you think you're running rich?

the smell of the exhaust and black tips on pipes. My vette had the same thing before the tune and it was running rich.

[axis]

Originally Posted by the_fast_one

the smell of the exhaust and black tips on pipes. My vette had the same thing before the tune and it was running rich.

Did you ever think that the smell and black soot just might be from the fact that you don't have cats to burn off the excessive fuel from the OEM tune? Even aftermarket tunes will have the smell of raw fuel, if you have no cats. You can't make the tune perfectly stoich all the time. There has to be some richness built into it.

[the_fast_one]

Originally Posted by axis

Did you ever think that the smell and black soot just might be from the fact that you don't have cats to burn off the excessive fuel from the OEM tune? Even aftermarket tunes will have the smell of raw fuel, if you have no cats. You can't make the tune perfectly stoich all the time. There has to be some richness built into it.

Yes it is common to always have gas smell with out running cats. But with the tuning of my vette it ran rich before the tune with headers and no cats. Also after lots of searching, talking to tuners, venders, and other people headers cause a car to run rich and not lean out of the box.

[axis]

Originally Posted by the_fast_one

Yes it is common to always have gas smell with out running cats. But with the tuning of my vette it ran rich before the tune with headers and no cats. Also after lots of searching, talking to tuners, venders, and other people headers cause a car to run rich and not lean out of the box.

I agree that it shouldn't run lean but the richness is always there. ALL cars come a little rich from the factory. The cats do a very good job of burning up the excess. Once you ditch them, the unburnt fuel is considerably more noticeable via smell and soot.