: low cat efficiency with kooks catted connection pipes

01-02-11, 01:40 AM
i keep throwing this code, i have kooks headers with the kooks catted connection pipes, and when i check the code with my dash hawk it saids that my cats have low efficiency:hmm: what should i do ? it is tuned

01-02-11, 08:10 AM
Most people turn off the rear O2s with headers, but you already know that.
Has this always been the case with the headers, or is the code recent? Might need to check the cats.

01-02-11, 10:12 AM
With my stock PCM I get these codes because of my magnaflow high flow cats (no headers). With my W4M tuned PCM, I don't get those codes so he must have turned off the rear O2s....

01-02-11, 11:15 AM
i think it is pretty much an accepted fact that the high flow cats that come with headers flow too fast to satisfy the OEM parameters measured by the pre/post O2 sensors.

My Random Technology cats did not throw a code during the brief time I had them installed with all the O2 sensors still on, but I had the rear sensors shut off anyway because I assumed the code would come while at the state inspection station some day.

I just wonder if that differential value that the ECM uses to throw the code could be changed somewhat rather than turning the rear O2 sensors off. If so, you will still have a warning system that the cat iteself was going out.

01-02-11, 12:24 PM
my tuner told me he doesnt like to turn off sensors, its recent ive had this setup for a year with the tune and it only started happening since maybe 3 weeks ago.

01-02-11, 02:36 PM
I get the same code with my exhaust setup. I am planning on ripping out the cats and putting in some off-road connection pipes with cut-outs in them next spring, and I'll just have my tuner turn off the O2 sensor codes.

01-02-11, 03:30 PM
Do you have hi flo cats or stock cats? In anycase it's the most common practice to turn them off (rear 02 sensors). They do not control any engine functions at all. They're just informative. Turning them off will affect nothing.