Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
I always fill up at Costco. Surprised to get bad gas from them because they sell top tier and the fuel never sits in the tanks long.Most probably it was a bad tank of gas. There is a gas station in town that whenever I buy gas from I get a check engine light with a code for catalytic efficiency below threshold.
They are E85 compatible, the factory tuning just can't do it.I have ran nothing but 87 and not a single problem with my 2020. She runs good and gets great millage. Switching octane should not cause a check engine light.
I would switch between 87 and E85 on my LS motor Tahoe and that never set a code. The computer learns what octain you are running and adjusts accordingly.
I wish Ford made these Ecoboosts E85 compatible. These would run great on E85 and make tuning that much better.
Jason, Sorry for the delayed response. I just don't get on here as often as I used to.That's interesting. My octane adjustment shows -1 even when I blended the 93 with 87 octane. So is there some other measurement for octane rating that I'm not watching? My recollection is that some value from one of the torque demand lookup tables is multiplied by the octane adjustment to hit max boost and timing, and that the "-1" is as good as it gets.
*edit* here's the article I was referring to about the optimal value for the octane adjustment.
![]()
Ford Ecoboost and the Octane Adjust Ratio Monitor
All Ford Ecoboosts use a dynamic multiplier known as Octane Adjust Ratio. This parameter can be monitored with the Accessport and is helpful in ensuring the fuel in your tank is adequate. It is especially important on an Ecoboost vehicle when peak power is expected (dyno tuning, racing) to...www.cobbtuning.com
See comment in linked thread below from Livernois regarding 91. Is it not correct?
Any Difference Using Higher Octane on 3.5L? - Ford F150 Forum - Community of Ford Truck Fans
2015 - 2020 Ford F150 - Any Difference Using Higher Octane on 3.5L? - I've been pumping 87 octane in the beast (stock) just curious if any gains of performance with the 91 or 92 octanes?www.f150forum.com
Actually Costco gas (91) causes my turbos to flutter at highway speeds. I don’t use it anymore. Not sure what about it that my engine doesn’t like!I always fill up at Costco. Surprised to get bad gas from them because they sell top tier and the fuel never sits in the tanks long.
If it wasn’t there he would know the second he started it for the first time…The man is spot on! Did not even think of that. You would hope he would notice the sound difference.
Who is your Tuner? Are you running an Auto Octane tune. Pretty rare for a Tuner to tell you to run 87 if you are actually on a performance tune.I have a ‘16 Expedition with a tune, and the Full Race “EcoBeast” kit. I go back, and forth, between octanes based on price. Pretty sure you know which octane I’m using nowadays!!!
The tuner told me I could run either octane. But, expect the most of the time from 93 octane.
So, I doubt that’s your issue.
Just found this thread and I also went from 87 to 93 to see how performance would change. I gradually added two or three tanks of the next octane over the last few weeks. Now I also have a check engine. Here's what Ford Pass is saying.
Damn... I had a feeling this was the case..As a driver of a gasoline tankersometimes you would by accident cross drop product, so long as gallons in tanks came out as amount billed all was good.Some dealers would ask you to cross drop and slip you some green. some would also pump regular into premim tanks at night. also some woild change fill markings on tanks. So driver would not get blamed, one station in ny the tanks were marked different every time you went there !!!! I would nerver buy premium unless it was only thing available. delivered for over 25 years I have seen it ALL !!!!

Please stay away from the ELM327 Clones. They are not what we should be recommending anymore. Seen way too many failures of the ones being sold now. FORSCAN is No longer recommending them, and is actually recommending against them. But yes, get a real scanner, and pull all codes.Get an ELM327 and pull the code, or have an auto parts store do it
As a driver of a gasoline tankersometimes you would by accident cross drop product, so long as gallons in tanks came out as amount billed all was good.Some dealers would ask you to cross drop and slip you some green. some would also pump regular into premim tanks at night. also some woild change fill markings on tanks. So driver would not get blamed, one station in ny the tanks were marked different every time you went there !!!! I would nerver buy premium unless it was only thing available. delivered for over 25 years I have seen it ALL !!!!
O2 Sensor. Like @Going_Going_Gone said, clear with a code scanner and see if it returns.Just found this thread and I also went from 87 to 93 to see how performance would change. I gradually added two or three tanks of the next octane over the last few weeks. Now I also have a check engine. Here's what Ford Pass is saying.
Man, I don't know who you worked for or what stations you delivered to, but if we cross dropped (even regular vs super, let alone crossed gas and diesel) we were IMMEDIATELY fired! No messing around. Plus our pumps and/or store would be shut down. Huge liability.As a driver of a gasoline tankersometimes you would by accident cross drop product, so long as gallons in tanks came out as amount billed all was good.Some dealers would ask you to cross drop and slip you some green. some would also pump regular into premim tanks at night. also some woild change fill markings on tanks. So driver would not get blamed, one station in ny the tanks were marked different every time you went there !!!! I would nerver buy premium unless it was only thing available. delivered for over 25 years I have seen it ALL !!!!