Why are there fuel trims for both banks?

I don't understand why GM has O2 sensors to get STFT data for both banks when the ECM has no ability to control fueling or spark for each bank independently, wouldn't it have been more cost efficient to just have one set of O2 sensors downstream where the exhaust combines from both banks? What is the logic behind having two sets of o2 sensors?

Allows to test cat efficiency and identify problems bank to bank

makes sense!

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Originally Posted by freaknbigpanda

I don't understand why GM has O2 sensors to get STFT data for both banks when the ECM has no ability to control fueling or spark for each bank independently, wouldn't it have been more cost efficient to just have one set of O2 sensors downstream where the exhaust combines from both banks? What is the logic behind having two sets of o2 sensors?

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What are you talking about? GM has controlled fueling bank to bank since the LT1s. The LT1s even have cylinder trims for each individual cylinder. Something that may actually exist in the P01s and P59s but nobody has actually looked into in the coding.

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Originally Posted by Fast4.7

What are you talking about? GM has controlled fueling bank to bank since the LT1s. The LT1s even have cylinder trims for each individual cylinder. Something that may actually exist in the P01s and P59s but nobody has actually looked into in the coding.

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Hmm so you are saying that per bank (or per cylinder) fueling controls exist, but they just aren't exposed via hp tuners? But the ECU does in fact control fueling for each bank separately?

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Originally Posted by freaknbigpanda

Hmm so you are saying that per bank (or per cylinder) fueling controls exist, but they just aren't exposed via hp tuners? But the ECU does in fact control fueling for each bank separately?

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There is a fuel trim per bank, but I always though that the actual reason was mostly to make sure and detect any issues. Individual controls are not exposed.

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Originally Posted by freaknbigpanda

Hmm so you are saying that per bank (or per cylinder) fueling controls exist, but they just aren't exposed via hp tuners? But the ECU does in fact control fueling for each bank separately?

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Per bank exists trim wise. That is why you see two different short and long term fuel trim values and two different injector pulse readings.

I did look at a 2005 P59 L31 .BIN file using Universal Patcher and it does have individual injector trims.