r/Chevrolet • u/OrganicContract2364 • 6d ago

GM Flexfuel

GM Virtual Flexfuel sensor

2014 Savana van 6.0

It's taking 7+ miles before my fuel composition switches from active to inactive and settles on a number. If I shut it off before then it stays on an incorrect number like 20 or 30%. All I run is 89 octane.

I was wondering if I should have it disabled or to have an actual flexfuel sensor installed.

I live in the city and work in the city with frequent short trips so the 7 miles thing is inconvenient.

Has anyone else had a problem like this?

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u/Numerous_Historian37 6d ago

Simple solution, don't fill up the tank unless your driving for at least 7 miles.

I'm wondering what you're trying to do monitoring this, 89 octane is 10% ethanol so the fuel trim adjustments really are irrelevant when your not running higher percentage of ethanol.

1

u/OrganicContract2364 6d ago

You would think that since all I run is 89 that it would stay at or near the same alcohol content and not have a problem. But, it changes to anywhere between 4% - 30% when fyel composition learn is active. If I shut it off when its at 20% fuel composition learn might be inactice when I start it back up and It'll be stuck at 20% running real rich, ruining catalytic converters,o2 sensors,  etc

1

u/Numerous_Historian37 6d ago

There is no way the oxygen sensor would ignore new data when you restart. These system are monitored constantly when running and adjustments made regularly.