Vortec 5.3/6.0/LS Single Bank Fuel Control Option

There was a thread about this subject back on Monodax. I was looking for information on the use of single bank fuel control. I was messing around with it this spring and never could get it to work like I 'Though' it should work. I'm using OBD2 Tuner Cat as well as HP Tuners custom 2 bar.

5.3L with two narrow band sensors wired as factory, wide band wired into HP Tuners aux input.

My situation is this: 5.3L Vortec, single turbo setup, both banks merge before the turbo, and single down pipe. The turbo is very close to the exit of the passenger side, so no room for an o2 sensor at this location to be able to only sample exhaust from that bank. So I opted to just control all 8 with a single o2 sensor. I accomplished this by setting the injector bank assignment of all 8 injectors to bank 1. I disable all diagnostics dealing with Bank 2, Sensor 1 and 2. What I found, is the PCM would never go into closed loop by its self, I had to use HP Tuners to force CLOSED loop and it would do it as long as I was forcing it.

Long story short, I had to have both narrow band sensors physically installed in the exhaust stream. The PCM would wait to see both sensors activity increase (indicating heated up sensor) before allowing closed loop, even though it only adjused fuel based on settings from Bank 1 Sensor. The LT ans ST fuel trim for bank 2 would usually MAX out one direction or the other, however, since fuel injectors were all tied to bank1 , fueling stayed correct. I also had to disable rich and lean diagnostics for bank 2.

So I have achieved 'single bank' fuel control, but still MUST have the bank 2 sensor installed and it must report activity for PCM to go into closed loop. It seems the check box 'single bank fuel control' had no difference.

Anyone else messed with this any?

I haven't messed with it. But I'm curious about your setup. Do you have a "dual exhaust" option? Is it still checked?

I've only seen the 'dual exhaust' option box on the black box vortec PCM's. On the 2002 5.3L calibration the option is actually called "Two Bank Fuel Control Option" The default value for this has an X in the box. Its under Calibration options in TunerCAT OBDII.

I had some split fuel trims and tried the "Two Bank Fuel Control Option" and had no effect on bank to bank fueling. Now this was on a 98 Vortec to 0411 PCM swap so not actual LS engine. Never have tried on LS engine. Nor did I try the Injector Asssignment.

Also removing all DTCs for post Cat 02 sensors had no effect and they had to be physically disabled to work.

I wonder if you disabled Readiness test on O2 sensors when trying one sensor?

Have you thought about simulating the output to both O2 sensors via one WB sensor? Some people seem to have luck with the simulation but I dont know if its truly proven for everyday use

I have use it many times. If it is a turbo application it will allow you to mount both O2's in a single pipe with no ill effects.

I had a car a few years back that when I had 2 bank fuel control turned off the fuel trims were close. I converted it to a 2 bar OS and they would be split again. I figured it had something to do with the COS.

I found on a bunch of cars it does not work like I expect it would. I found in a very few it does. I have gone over the calibrations in hex and found a few settings that may make it work, but I have not done further testing
If the sensors are in 1 pipe it fixes the fuel trims.

Was experimenting with the Dual Bank/Single Bank on my L29 454 today, no worky (I know, I have a dead right bank O2). But looking at the L30 (the 305), it is factory single bank and works (obviously or GM wouldn't have shipped it), but it also has 3rd O2 sensor checked too. I will experiment more tomorrow on it.

The other question is did GM do something like ground out the Bank 2 sensor input?

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Originally Posted by EyesofThunder

Was experimenting with the Dual Bank/Single Bank on my L29 454 today, no worky (I know, I have a dead right bank O2). But looking at the L30 (the 305), it is factory single bank and works (obviously or GM wouldn't have shipped it), but it also has 3rd O2 sensor checked too. I will experiment more tomorrow on it.

The other question is did GM do something like ground out the Bank 2 sensor input?

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Yes the Vortec 305 has that 3rd precat O2 sensor and the single aftercat O2 sensor.
The L31 350 and L29/21 454 uses the dual precat and dual aftercat sensors.

peace
Hog

I tried it, still need to datalog it, but at least from what I have started with I haven't got single bank to work (even with 3rd O2 checked) on a 2000 K3500 calibration in my 99 K2500 454 Suburban.

It runs quite badly with 3rd O2 checked and no other changes.

Quote:

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Originally Posted by Hog

Yes the Vortec 305 has that 3rd precat O2 sensor and the single aftercat O2 sensor.
The L31 350 and L29/21 454 uses the dual precat and dual aftercat sensors.

peace
Hog

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