TonyB84

Either I told the guy the wrong kind of gas, or he put the wrong gas. I'm not sure. I just had the tank topped off to full. I think I just put 3.57 gallons of 87 in my tank based on the cost and gallons. I usually always watch them press the button for 93, but didn't this time.

The rest of the 16 gallon tank was 93. Will this mess things up if I run the Brenspeed 93 Street tune with that gas in the tank? Or should I switch back to stock until I run the gas out? Should I put part of a bottle of octane booster in my tank?

Thanks for any help,
Tony

11SHELBYGT500

You're running 90 if you mixed 87 and 93. I don't think you'll have a problem.

MARZ

Eh, I don't know. I'd rather be safe than sorry. If I were you, I'd flash my car back to stock and run a couple of tanks of 93 through it before re-loading my Brenspeed tune.

TonyB84

Ya, I've had the car with the stock tune for 10 months, I can for another week or so. After I get down to under 30 miles to E and then fill it with 93 I'm going to go back to the 93 tune. Thanks for the advice.

Tony

Ltngdrvr

It would equal 90 octane if it was half 87 and half 93 but he said they only put 3.5 gallons of 87 in it to top it off.

They don't turn the knock sensors off in the tune so it should still pull timing if it hears knock so I would just drive it and when it gets down to half then fill it back with 93 and don't worry about it.

11SHELBYGT500

True^^^

2012GT

Do you have CAI? putting it back stock will cause it to lean out with the CAI. you should have an 87 tune on your tuner. Steeda gave me an 87 race and 93 race tune on my tuner for situations just like yours.

TonyB84

I don't have a CAI. I have an 87 Street tune. The other 2 I got were 93 Street and 93 Race.

Tony

Wander

Dump a can of octane boost in the tank. Thats what I do when I drive out west and can't find 91 octane. Always worked.

Everett

As long as your tune did not affect knock sensor function then gas doesn't matter. The computer will compensate

tapd117

I did this at the pumps today, put about 4 gallons of regular in my Shelby not thinking, da!!! Stopped filed up with premium and just drove off, the on board computers will adjust. The car runs fine, I wouldn't worry about it. You most likely ended up with a 91.5 octane blend and I really think it is no big deal..........

GG

2012GT

1) put in your 87 street tune. run gas down low as possible. 2)fill up with 93. install 93 street tune. run gas as low as possible. 3)fill up with 93, install 93 race tune. you'll be fine if you do that. Like the other guys said, your knock sensors will PROBABLY compensate but you are 100% safe using the above method.

AzPete

Just drive it........not a major issue if you are not racing it at every light.

gunfighter36

You don't pump your own gas?...

MARZ

Again, I'd prefer being safe than sorry. While I know the new 5.0L has sophisticated knock sensors, who knows what an aftermarket tune does to them? Also, having seen a car or two whose #8 pistons have grenaded, I don't know if I'd feel safe relying solely on the knock sensors.

TonyB84

I'm in NJ, it's all full service, you can't pump it yourself.

Tony

assasinator

pull 5 degrees of timing in the tune and drive it for a few tanks.

godspunk32

One of the many reasons I hate living in New Jersey.

BTW, Tony...sorry I didn't reply to your Facebook message until later. Sometimes they forward to my phone, and sometimes they don't, so I see them at random times!

JR

cdynaco

That's what I think. Easy!

SoSlowGT

Your mixture of 3.57 gallons of 87 in a 16 gallon tank with the remaining gas (12.43 gallons) being 93 octane should theoretically put your octane rating at 91.66 octane. Not a big difference but better safe than sorry. I would run a stock tune until you empty that fuel out of your tank.