I hav seen a couple of posts that say that if you get the ARH headers and no reflash you will get an emmissions related SES light.

Two questions;

1) Is the SES light due to the fact that emissions are infact out of the required range? If so why are CARB approved cats doing this, if not why is there an SES light? Is it due to the car running lean/rich because of the computer trying to compensate for the increased airflow?

2) (This is mainly for oxidisr but anyone else feel free to chime in) Will the Magnaflow cat back throw this same code if you put on Magnaflows high flow cats?

I am asking this because deep down under my tire smoking interior lurks a bit of a greenie. I often justify modds by saying that in the end most airflow related mods are environmentally freindly as the engine requires less fuel during normal (read non tire shredding) throttle positions, as there are less pumping losses (the same reason AFM/DoD/MDS/842 etc work... you are not pumping air through those cylinders when the system is active). If I am putting out more NOx because of these mods I might be less inclined to do them.

Thanks

Magna Flow will cause no issues. I had mine on for approx 600 miles. 0 issues. Any vehicle you put long tubes on that is OBD2 will set a code for catalyst efficiency (P0420/430). A simple tune will get rid of this.

Magna Flow will cause no issues. I had mine on for approx 600 miles. 0 issues. Any vehicle you put long tubes on that is OBD2 will set a code for catalyst efficiency (P0420/430). A simple tune will get rid of this.

I guess what I am asking is WHY is there I code?

For the long tube ARH the cats are located farther from the engine than the stock cats. Because of this it takes a little longer for them to get up to working temperature, this coupled with the higher flow has the rear O2 sensors seeing readings that it is not expecting and it is throwing the code. For a short period of time you would be polluting a little more than the stock system, but once it comes up to temperature the pollution control should be similar.

I would guess that the Mangaflow high flow cats will not have this problem since they are in the stock location, but Oxidisr needs to confirm this.

Neil
'08 MGM G8 GT

Thanks racerns... that makes sense.

I am willing to bet that I will not be putting out any extra pollution as NOx production only really starts up once the engine gets hot....

standing by for oxidisr..

Thanks racerns... that makes sense.

I am willing to bet that I will not be putting out any extra pollution as NOx production only really starts up once the engine gets hot....

standing by for oxidisr..

You are correct, the NOx emmissions should not be higher but you would be seeing higher hydrocarbon (HC) emissions for a short time as the cat heats up.

Peut etre, je crois que tu a la raison....

makes sense.