Differential swap, TCM Tunes and Smog Inspections

[Gboy]

Looking to do a differential swap(Camaro SS 3.27 LSD) and everything I read it needs shift points changed in the TCM. With the current California smog inspections looking for changes to the ECM, are changes to the TCM tune(shift points) checked and could they cause a failed smog inspection?
I did a quick search and really didn't come up with anything. If there's a sticky or a previous post addressing this please point me in that direction. Thanks.

[smwalker]

We have been discussing it a bit here:
https://www.newcaprice.com/forum/viewto ... 255#p35255

Summary, Only the Engine Diagnostic file seems to be polled. So TCM should be safe for changes. And since they seem to be ignoring any cars with AFM for tunes you are safe there as well. For now.

[Gboy]

I saw that thread, but didn't see anything that was related to the TCM. Some interesting info. Thanks.

Just being nosy (and not knowing a lot about tuning an ecu/ecm), how much adjusting can be done? Not deleting cats or anything Just optimizing fuel/timing etc. Will that be picked up by State during a test? Not just talking our vehicles, but any others? Sorry if this too much a noob question.

[smwalker]

That's the unknown. We know no monitors can be turned off or bypassed. So any adjustments that could trigger a cel or prevent a monitor from completing will be a problem. So I think anything you do with in those parameters is fine for the AFM engines.

[JoeR]

California SMOG Checks will run CVN numbers that are stored in the PCM. They're generated using a complex algorithm and can't be spoofed. If you make any engine related changes, even something as harmless as changing fan cycling temps, it changes the CVN. If you don't have OEM CVNs in the vehicle, you can't pass SMOG. Transmission changes are OK. Engine changes are not.
Joe

[smwalker]

California SMOG Checks will run CVN numbers that are stored in the PCM. They're generated using a complex algorithm and can't be spoofed. If you make any engine related changes, even something as harmless as changing fan cycling temps, it changes the CVN. If you don't have OEM CVNs in the vehicle, you can't pass SMOG. Transmission changes are OK. Engine changes are not.
Joe

Except for GM AFM engines. They are letting them through because so many people have had to tune out CEL after a DOD delete.

BUt yu are correct any other non AFM enging any change is a fail. Although may of the european vehicle tuners have seemed to find away around it.

[JoeR]

Except for GM AFM engines. They are letting them through because so many people have had to tune out CEL after a DOD delete.

BUt yu are correct any other non AFM enging any change is a fail. Although may of the european vehicle tuners have seemed to find away around it.

That's actually pretty cool of them to give them an exception, even though DOD cars can be just as clean after a delete.