I have a traditional tune. I have a swapped in LQ9.
About 10 days ago I had 6.0 dual cats & Magnaflow Escalade/Denali 15734 cat-back installed (from 5.3 y-pipe and basically factory exhaust). Immediately got a CEL. Replaced front O2 sensors and problem corrected. Took two trips totaling close to 1000 miles. Zero issues.
A week later CEL reappeared, along with mpg loss of about 1.5-2.0 and slightly reduced power. Code was for Bank 2 low converter efficiency. Replaced PS (bank 2) post cat O2 sensor (with a used one). Power and crazy good mileage returned almost immediately. About 24 hours later, CEL popped up again...ugh. Muffler shop said it would likely recur, and it did.
6.0 cats are from an 04 Denali with verified 68K miles.
Is my PS (bank 2) converter toast?
Should I try a new bank 2 rear O2 sensor?
Should I send in my ECM to get O2 sensor delete? If so, just the rear two?
I reused the 5.3 O2 sensors because the connectors on the 6.0 sensors were different. It looks like all four 5.3 O2 sensors are identical (same connector).
New normal mpg has been around 16-16.5 at 70 with cruise. With CEL on, it is 15-15.5. After replaced rear Passenger Side O2 sensor (w/used), mpg shot up to 18.5 at 70 with restored power...then a CEL and back down to low 15 mpg. It is slowly climbing back up towards 17, but power seems slightly off and CEL is still on.
I'd rather not throw money at it for new cats or take it to a dealer. What would you suggest?
I think that the long term solution is a 6.0-specific bank 2 exhaust manifold (w/o-ring, not donut), another used bank 2 mid-pipe w/cat and new rear O2 sensors, or perhaps rear O2 sensor delete.
My goal (obviously) is 1. max power, 2. mpg and 3. without any codes.
About 10 days ago I had 6.0 dual cats & Magnaflow Escalade/Denali 15734 cat-back installed (from 5.3 y-pipe and basically factory exhaust). Immediately got a CEL. Replaced front O2 sensors and problem corrected. Took two trips totaling close to 1000 miles. Zero issues.
A week later CEL reappeared, along with mpg loss of about 1.5-2.0 and slightly reduced power. Code was for Bank 2 low converter efficiency. Replaced PS (bank 2) post cat O2 sensor (with a used one). Power and crazy good mileage returned almost immediately. About 24 hours later, CEL popped up again...ugh. Muffler shop said it would likely recur, and it did.
6.0 cats are from an 04 Denali with verified 68K miles.
Is my PS (bank 2) converter toast?
Should I try a new bank 2 rear O2 sensor?
Should I send in my ECM to get O2 sensor delete? If so, just the rear two?
I reused the 5.3 O2 sensors because the connectors on the 6.0 sensors were different. It looks like all four 5.3 O2 sensors are identical (same connector).
New normal mpg has been around 16-16.5 at 70 with cruise. With CEL on, it is 15-15.5. After replaced rear Passenger Side O2 sensor (w/used), mpg shot up to 18.5 at 70 with restored power...then a CEL and back down to low 15 mpg. It is slowly climbing back up towards 17, but power seems slightly off and CEL is still on.
I'd rather not throw money at it for new cats or take it to a dealer. What would you suggest?
I think that the long term solution is a 6.0-specific bank 2 exhaust manifold (w/o-ring, not donut), another used bank 2 mid-pipe w/cat and new rear O2 sensors, or perhaps rear O2 sensor delete.
My goal (obviously) is 1. max power, 2. mpg and 3. without any codes.
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