P0171 and p0175, Lean and Rich, Real conundrum

[SaltyC20]

Hello all. I have a 1969 C10 with a 4.8L swap out of a 2004 Tahoe with a 4L60E. I am currently experiencing two codes P0171 (Bank 1 Lean) and P0175 (Bank 2 Rich). And to top it off it recently started showing P0756 (shift solenoid), but I am ignoring that for now.

The engine runs well. At high RPMs it has plenty of power and can really spin the tires. But off the line it often stumbles and even pops on the passenger side exhaust (like its rich). By the time I am exiting the intersection, the engine picks up and I inadvertently spins the tires, as the power comes on very suddenly.

The truck is DBW, and the swap is recent. My computer is from Brendan at LT1Swap. I have replaced the spark plugs, and they all looked like a rich mixture. I have checked for vacuum leaks by spraying carb cleaner, but cannot seem to find any. The engine came with the O2 sensors cut off the harness, so I bought a pair of new boschs 15895 off ebay. I also checked for exhaust leaks upstream of the o2 sensors, but don't have any.

My brain is spinning with possible problems: Maybe burning coolant, I botched the harness job, bad head gasket, etc. Too many maybes. Please help me troubleshoot this bad boy.

[BR3W CITY]

Possible you have a stuck injector(s). Usually having 2 different codes on opposing banks means something further up the system is causing the issue. I'd also verify your MAF wiring, but generally that causes the same code on both banks.

[SaltyC20]

Hey Brew, I was hoping you would answer. I did do a low flow bench test before I installed, but I could still see one being stuck. Can you elaborate on the stuck injector?

I don't understand the control logic enough to how that would cause one bank to go lean one go rich? For example, How would a stuck closed injector on bank 1 (lean) cause bank 2 to show a rich code?

What if I moved one set of injectors to the other side of the engine? Any ideas how to troubleshoot?

[SaltyC20]

Regarding your comment about MAF wiring. I think it is spot on because the Scan tool is showing correct IAT and Air Flow Rates. I can't remember the value, but my memory says about a 1lb/min at idle. I got my first scan tool last night, so I haven't had much time with it.

[ls1nova71]

You dont by chance have the left and righ O2sensor wires crossed do you? Might be worth a check.

[SaltyC20]

Thanks for the reply ls1nova. Big fan of your builds. I thought the same thing,but quickly dismissed it,because no way right? However I will look. To confirm: bank 1 is the drivers side?

[SaltyC20]

well dang it, I feel dumb. Ls1nova you were right. I had the o2 sensor wires swapped in the harness. The engine is much smoother now.

It is suprising how well the engine ran with the o2 sensor hooked up backwards. I have been so impressed with the 4.8L. Now on to the shift solenoid issue. Thank you for your help.