Relocate Rear 02s on X-Pipe with HFCs?

[pbonsalb]

I have noticed that x-pipes with high flow cats eliminate the primary cats from the stock position at the beginning of the x-pipe and replace them with high flow cats in the location of the stock secondary cats before the x in the x-pipe. However, none appear to relocate the rear 02 sensor to after the new and relocated high flow cats. A new bung and an extension harness could do this.

Anyone tried this? Is the ECU so good that the rear 02 must measure the AFR just 16 inches after the front 02 to avoid readiness or other codes?

[Dave07997S]

Originally Posted by pbonsalb

I have noticed that x-pipes with high flow cats eliminate the primary cats from the stock position at the beginning of the x-pipe and replace them with high flow cats in the location of the stock secondary cats before the x in the x-pipe. However, none appear to relocate the rear 02 sensor to after the new and relocated high flow cats. A new bung and an extension harness could do this.

Anyone tried this? Is the ECU so good that the rear 02 must measure the AFR just 16 inches after the front 02 to avoid readiness or other codes?

A few have tried this and they still got a SES light for increased emissions.

Dave

[pbonsalb]

Is it because the HFC were located further back that the front and rear 02 differential was too great?

Or is it because the HFC were too HF? In other words, is there any evidence that 200 cell cats are insufficient but 300 cell cats work? The stock primary cats are probably 400 cell.

[M3DCTBT]

Originally Posted by pbonsalb

Is it because the HFC were located further back that the front and rear 02 differential was too great?

Or is it because the HFC were too HF? In other words, is there any evidence that 200 cell cats are insufficient but 300 cell cats work? The stock primary cats are probably 400 cell.

.

A proper readiness tune is calling your name. Stock wiring.

[GTM_Challenge]

Even some of the high flow, high cell count cats seem to eventually cause a CEL. its all been tried pretty much

[Dave07997S]

Originally Posted by pbonsalb

Is it because the HFC were located further back that the front and rear 02 differential was too great?

Or is it because the HFC were too HF? In other words, is there any evidence that 200 cell cats are insufficient but 300 cell cats work? The stock primary cats are probably 400 cell.

I think its an issue of the cats being to high flow, as even 200cpi metallic cats in the OEM primary location still will kick off a CEL without 02 extenders like Fabspeed uses as well as Gintani.

You could probaby get away with running HFCs in the secondary position and run the 02 sensors back there but with an extender and it may work..no one I know has done this successfully.

Keep in mind the OEM secondary cats are 200cpi...

Dave

[pbonsalb]

I do not think secondary cats do anything for readiness since they are located past the secondary 02s. Readiness will be determined by the cats preceding the secondary 02, wherever each are located.

200 cell cats may be marginal. Some of the HFC x-pipes use 200 cell (AA, Fabspeed), some 100 cell (Akra), and probably some 300 cell. Most of them don't help OBD2 inspection because the HFC are located after the secondary 02.

I'd like to find something that works. M3DCTBT says he has a combination that works.

[Dave07997S]

Originally Posted by pbonsalb

I do not think secondary cats do anything for readiness since they are located past the secondary 02s. Readiness will be determined by the cats preceding the secondary 02, wherever each are located.

200 cell cats may be marginal. Some of the HFC x-pipes use 200 cell (AA, Fabspeed), some 100 cell (Akra), and probably some 300 cell. Most of them don't help OBD2 inspection because the HFC are located after the secondary 02.

I'd like to find something that works. M3DCTBT says he has a combination that works.

I understand, I am just saving my OEM xpipe and when I have to smog I will just switch back to OEM, this is almost 4 more years for me before I have to smog.


Dave