2002 Express Van 5.7 Dual Exhaust to Single Exhaust.

[Fast355]

Not completely sure what you want to do or asking but dual vs single cat systems only differ with the after cat sensor or sensors that monitor cat/cats efficiency. Neither have anything to do with engine operation. Both would still use 2 pre cat sensors. You could just disable the after cat/cats O2s and it would be fine. You just wouldn't have any catalyst monitoring should a cat go bad.

Incorrect, 3 upstreams on the factory single cat trucks. It very much does change how the engine runs.

GM has factory Express van tunes for L31s with a single cat as well as no cats and even no 02s at all. Some of the L31 calibrations are open loop only even.

Tunercats has the option to directly edit the Dual vs Single cat exhaust configuration, I made a dual cat 305 calibration when I put the L30 into my Tahoe and also made a single cat L31 calibration when I put a Mercruiser version of the HT383E into a 2005 Astro.

[Fast355]

Factory exhaust and 02 configuration on a single catalyst Vortec. 3 pre-cat 02s. An 02 after each manifold and 1 after the Y-pipe. 1 behind the cat.

[Fast355]

This exhaust matches the open loop only catless L31. My 2003 L31/5spd 4x4 GMT800 Sonora had the same type of setup but did use front 02s only. Factory EGR deleted, LS truck airbox and 85mm MAF on that one.

[Themerlen]

Incorrect, 3 upstreams on the factory single cat trucks. It very much does change how the engine runs.

GM has factory Express van tunes for L31s with a single cat as well as no cats and even no 02s at all. Some of the L31 calibrations are open loop only even.

Tunercats has the option to directly edit the Dual vs Single cat exhaust configuration, I made a dual cat 305 calibration when I put the L30 into my Tahoe and also made a single cat L31 calibration when I put a Mercruiser version of the HT383E into a 2005 Astro.

This would be the setup that I have. You wouldn't still happen to have a .bin file for an single cat L31 you'd be willing share, or know where to find one. All the ones I've found so far are dual cat. But now that I know it exists, it might make it easier to find.

[MO LS Noobie]

Upstream sensor, (pre-cat) on bank one is B1S1. Upstream sensor (pre-cat) bank two is B2S1. The typical configuration with two post cats are numbered B1S2 and B2S2. A simpler way to do what I think you want to do would be leave B1S1 and B2S1 alone and just delete the post cat (sensor 2) data from your existing tune.

[Themerlen]

Upstream sensor, (pre-cat) on bank one is B1S1. Upstream sensor (pre-cat) bank two is B2S1. The typical configuration with two post cats are numbered B1S2 and B2S2. A simpler way to do what I think you want to do would be leave B1S1 and B2S1 alone and just delete the post cat (sensor 2) data from your existing tune.

This is likely what I'll end up doing, at least to start, and if I can get a correct bin file like Fast mentioned above then I can switch gears towards that. I like to keep as much functional as possible, but sometimes it doesn't always work out that way, at least in the beginning, and was hopeful that others knew of a way other than just deleting what isn't working correctly.

[2xls1]

That 3rd upstream is used only on the 96,97 5.0Ls. Tunercat only shows it in the DTC list for those years. It is B1S2. The 98-99 5.0L just use B1S1, B1S2 and B1S3. B1S3 is after cat. Those are the only ones in the DTC list for those years. If you are doing a 0411 swap you will be using a later year OS so you will only need B1S1 and B2S1 O2s.