Problem with bung W02 bung placement - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

1KillerSS · 05-17-2015, 02:23 PM

Dont replace your pre cat sensors, you need those, but the post cat sensors, you dont need.

axis · 05-17-2015, 03:16 PM

Quote:

Originally Posted by 1KillerSS

You have 4 one before the cats and one after, on each bank. If your tuning your car, then all you need to do is turn off the codes for the rear sensors. Disconnect one of the post cat sensors, and disable the associated codes with it. Zip tie the loose harness out of the way.

This.

The rear sensors only check cat efficiency. Just know that the readings will be somewhat affected by the cat.

rrrocketman · 05-17-2015, 07:05 PM

Ok that part I fully understand and agree with. However, the catalyst changes the chemistry of the exhaust stream so does that not defeat the purpose of sampling it with a wideband? You'd get 14 or something when it's actually 14.3.

Oh... and as an aside... why the hell are there 2 cats per bank anyway?

1KillerSS · 05-17-2015, 08:35 PM

Quote:

Originally Posted by rrrocketman

Ok that part I fully understand and agree with. However, the catalyst changes the chemistry of the exhaust stream so does that not defeat the purpose of sampling it with a wideband? You'd get 14 or something when it's actually 14.3.

Oh... and as an aside... why the hell are there 2 cats per bank anyway?

I dont know the exact amount of variance between pre and post cat O2 readings, but I doubt its that large. Regardless you can adjust your formula in HPTuners to account for any offset you may get.

rrrocketman · 05-17-2015, 11:03 PM

That's a possibility. I'd have to compare the value to a known baseline however, like stoic, to know what the offset was and then the offset would have to be consistent at all AFRs. I guess it doesn't HAVE to be like that but I figure if you're picky enough to get a wideband in the first place, might as well ensure that it's accurate to +/- 0.5 at least.

1KillerSS · 05-17-2015, 11:10 PM

There are plenty of people who have their wideband O2 sensors post cats, cant recall anybody having tuning issues regarding the variance of readings pre and post cats. Keep in mind most dyno shops stick the O2 sensors they are using in the tail pipe.

rrrocketman · 05-18-2015, 07:19 PM

THAT is true. And I always wondered if they had some sort of correction algorithm at work or something... I really need to locate some proper scientific literature from people who have done gas analyses pre and post cat. I'm sure such a thing exists.

05-17-2015, 02:23 PM	#15
1KillerSS Too much is never enough! Drives: AGP TT SS [COTW] 4/20/15 Join Date: Feb 2014 Location: Toledo,OH Posts: 4,149 View My Garage	Dont replace your pre cat sensors, you need those, but the post cat sensors, you dont need. __________________ AGP TT kit, 54/57 Forged rotating assembly, Custom grind cam... Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock. 747 whp 714wtq *Build thread* http://www.camaro5.com/forums/showth...55#post8107855

05-17-2015, 07:05 PM	#17
rrrocketman youtube.com/c/ChrisCamaro Drives: 2013 Camaro SS w/ NPP and Hi Wing Join Date: Feb 2014 Location: Toronto Posts: 254	Ok that part I fully understand and agree with. However, the catalyst changes the chemistry of the exhaust stream so does that not defeat the purpose of sampling it with a wideband? You'd get 14 or something when it's actually 14.3. Oh... and as an aside... why the hell are there 2 cats per bank anyway? __________________ https://youtube.com/c/ChrisCamaro

05-17-2015, 11:03 PM	#19
rrrocketman youtube.com/c/ChrisCamaro Drives: 2013 Camaro SS w/ NPP and Hi Wing Join Date: Feb 2014 Location: Toronto Posts: 254	That's a possibility. I'd have to compare the value to a known baseline however, like stoic, to know what the offset was and then the offset would have to be consistent at all AFRs. I guess it doesn't HAVE to be like that but I figure if you're picky enough to get a wideband in the first place, might as well ensure that it's accurate to +/- 0.5 at least. __________________ https://youtube.com/c/ChrisCamaro

05-17-2015, 11:10 PM	#20
1KillerSS Too much is never enough! Drives: AGP TT SS [COTW] 4/20/15 Join Date: Feb 2014 Location: Toledo,OH Posts: 4,149 View My Garage	There are plenty of people who have their wideband O2 sensors post cats, cant recall anybody having tuning issues regarding the variance of readings pre and post cats. Keep in mind most dyno shops stick the O2 sensors they are using in the tail pipe. __________________ AGP TT kit, 54/57 Forged rotating assembly, Custom grind cam... Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock. 747 whp 714wtq *Build thread* http://www.camaro5.com/forums/showth...55#post8107855

05-18-2015, 07:19 PM	#21
rrrocketman youtube.com/c/ChrisCamaro Drives: 2013 Camaro SS w/ NPP and Hi Wing Join Date: Feb 2014 Location: Toronto Posts: 254	THAT is true. And I always wondered if they had some sort of correction algorithm at work or something... I really need to locate some proper scientific literature from people who have done gas analyses pre and post cat. I'm sure such a thing exists. __________________ https://youtube.com/c/ChrisCamaro