New tune reededafter removing high flow cats? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

bsimms89 · 09-10-2021, 06:10 PM

I had my car dyno tuned 5 years ago by a good local tuner when I installed headers, an intake, ported throttle body, high flow cats, and exhaust.

I just installed a 2 step rev limiter to use at the track and didn’t want it to melt out the cats overtime so I just swapped out the high flow cats for straight pipes. I didn’t know if I need to get a new tune to account for the additional air flow, but I’m assuming since it’s tuned to air/fuel ratio removing the cats shouldn’t make any difference and it should still add fuel to reach the commanded ratio,am I correct? I’m not worried if I can pick up a little power by retuning after deleting the pipes, I just want to make sure I won’t run lean without a new tune.

The tuner previously turned off the CELs from the rear O2 sensors since I was getting them even with the high flow cats so I don’t think I’m going to get any codes. I would just give the tuner a call but he retired and isn’t around anymore. I’ve never dealt with tuning anything with cats before.

1JEWLDSSRS · 09-11-2021, 03:59 PM

From what I have read on here and understand, you should be alright with the tune you have now because the difference in airflow in the HF cats and an off road mid, in your case, straight pipe is negledgable, not much if any to be gained, and our ECU's can compensate for that minor change. Good luck..

09-10-2021, 06:10 PM	#1
bsimms89 Drives: 2012 SS/RS Vert & 2017COPO#23 SC350 Join Date: Apr 2012 Location: NY Posts: 105	New tune reededafter removing high flow cats? I had my car dyno tuned 5 years ago by a good local tuner when I installed headers, an intake, ported throttle body, high flow cats, and exhaust. I just installed a 2 step rev limiter to use at the track and didn’t want it to melt out the cats overtime so I just swapped out the high flow cats for straight pipes. I didn’t know if I need to get a new tune to account for the additional air flow, but I’m assuming since it’s tuned to air/fuel ratio removing the cats shouldn’t make any difference and it should still add fuel to reach the commanded ratio,am I correct? I’m not worried if I can pick up a little power by retuning after deleting the pipes, I just want to make sure I won’t run lean without a new tune. The tuner previously turned off the CELs from the rear O2 sensors since I was getting them even with the high flow cats so I don’t think I’m going to get any codes. I would just give the tuner a call but he retired and isn’t around anymore. I’ve never dealt with tuning anything with cats before. __________________ 2012 IOM Camaro Convertible 2SS/RS, A6/L99, ARH Longtube headers, high flow cats, x-pipe & mufflers CAI Cold Air Intake, Kaltech Tuned 2017 COPO #23 Black w/ Supercharged LSX350 2014 Raptor 6.2L Tuxedo Black Metallic w/ 2.9L Whipple, 78Lb/hr fuel injectors, Ford Racing Dual 65mm cobrajet throttle body, kooks headers & exhaust. 1969 Camaro SS (original SS350), Black w/ white Rally Stripes, new ZZ502ci 502hp motor, muncie 4 speed, 4.11 rear

09-11-2021, 03:59 PM	#2
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 14,043	From what I have read on here and understand, you should be alright with the tune you have now because the difference in airflow in the HF cats and an off road mid, in your case, straight pipe is negledgable, not much if any to be gained, and our ECU's can compensate for that minor change. Good luck.. __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.