Air/Fuel ratio

I just got the Air/fuel ratio programmed into the scangauge.. and I'm curious what it should be reading on the highway? Right now it's steady at 14.5.

Anyone know what it should be at?

 

Ideal with pure octane would be 14.7:1, but with different additives in the gas it will vary. If it's oxygenated fuel, then the ratio will be lower. Your O2 sensor should automatically adjust air/fuel ratio so there is no excess oxygen or fuel (one way or the other) going to the catalytic converter.

 

Right on, thanks! Guess it's damn near perfect then.

 

You won't see much variation in a NA vehicle unless something is massively wrong.

 

Monitoring your long term fuel trim will help you too. Tells you how much the computer is adjusting the injectors (open time) to keep the air fuel ratio at ideal 14.7:1.

 

Good to know. I'll be programing the fuel trim into the scangauge too, now.

 

14.5 is good.

 

Where can I find the command code for the AFR to have my scan gauge report it ? Thanks

 

I see this post is old but I have some air to fuel ratio questions.
Currently my AFR is fluctuating from 12:1 to 18:1 consistently at idle along with an idle surge.
I'm wondering if anyone knows what would cause this?

 

I would check for a vacuum leak first.

 

AFR is kinda pointless, it fluctuates.

Truly what matters is fuel trim long term %, if its +/- 10% thats all that matters.