What Fuel Should I Be using?

[hunterrrjohnson]

I bought a 2019 Mustang GT from a dealer. Car was originally from Alabama. Came with Headers, Intake, and a Tune.
I’ve been putting 93 in it for about a year now and just seen a post abt somebody’s AFR reading 9.8 at cruising and Idle, and 20 at Deceleration. People wear saying it’s on an E85 tune and he shouldn’t be running 93? Was wondering best way to figure that out? Or how true that is.

Sponsored

 

[KeyLime]

I'll have to check, but I think 14:1 is the typical AFR for gas motors.

 

[K4fxd]

If you are on an E85 tune I can't see you driving for a year without it throwing a check engine light.

 

[NGOT8R]

9.8 is indicative of an E85 tune. I just switched from my E85R tune to Flex and the car runs like crap. I had to do it for a road trip and I can’t wait to run the 93 out and put it back on E.

 

[K4fxd]

If it's pulling 30% fuel it should throw a mil in 10 miles or less. Maybe OP is ignoring it

 

[NGOT8R]

If it's pulling 30% fuel it should throw a mil in 10 miles or less. Maybe OP is ignoring it

Could be. I met another member on here in person, who had bought a tuned car with no device to accompany it and was running 93 octane with 9.8 showing on the gauge. His CEL was on too.

 

[NightmareMoon]

I bought a 2019 Mustang GT from a dealer. Car was originally from Alabama. Came with Headers, Intake, and a Tune.
I’ve been putting 93 in it for about a year now and just seen a post abt somebody’s AFR reading 9.8 at cruising and Idle, and 20 at Deceleration. People wear saying it’s on an E85 tune and he shouldn’t be running 93? Was wondering best way to figure that out? Or how true that is.

What’s your AFR at idle and while cruising? Hows the car running with 93? Whats your cruising gas mileage?

Theres no real way to be sure if you have a 87,91 or 93 tune (93 is most surely ok), but we can probably rule out E85 based on these other things.

 

[black22gt]

AFR tells part o' the tale. As others have stated, itll target 9.8:1 if it has an e85 tune, otherwise it targets 14:1 for gas. Now whether that tune is 87/91/93 compatible or just for 93 is trickier without a tuner to ask to check. My thoughts are if someone tuned it for intake and headers, they probably did a 93 to get the most power from the tune. Could be wrong, but thats the safer/more expensive assumption.

 

[WildHorse]

I’ve been putting 93 in it for about a year now and just seen a post abt somebody’s AFR reading 9.8 at cruising and Idle, and 20 at Deceleration. People wear saying it’s on an E85 tune and he shouldn’t be running 93?

ok, so you seen some other post for 9.8 AFR. That's for E85.
20:1 AFR is decel fuel cutoff ... one of Fords brilliant ideas.

What's YOUR AFR showing ?

 

[The Demon]

Gasoline?

Sponsored