GM "Fuel Trim Enable"

[George7941]

Using the Tech 2, under "Fuel System" are four functions
1) Cyl Power Balance
2) Fuel Injector Balance
3) Fuel Trim Reset
4) Fuel Trim Enable

I understand the first three, what does Fuel Trim Enable do? My best guess - when in open loop, force engine to go into closed loop.

 

[Trav]

That's it in a nutshell, some codes will lock the tables and force open loop, it also starts the learning process AFAIK.

 

[WobblyElvis]

I ain't no genius with these things but I would think "fuel trim enable" would normally be set to "enable". This would permit fuel trim when the engine/o2 sensor is up to temp. Disabling fuel trim would effectively stop any fuel trim and keep the system in open loop.

My 2 cents.

 

[Trav]

That's correct.

 

[Trav]

Okay I understand now what you are saying. Yes normally enabled but for diagnostic reasons you may want to disable it and get readings when the engine is running from the tables alone like it was in open loop.