Used 87 instead of 93...check engine light.

[Soliyou]

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.

 

[fjordexpedition]

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.

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.

 

[LokiWolf]

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.

They are E85 compatible, the factory tuning just can't do it.

https://www.expeditionforum.com/threads/corn-fun.51182/#post-471428

Our 2020 is currently daily driven on a ZFG E85(Stock Pump/Injectors) Tune.

You can run to about E20 on stock tuning without issues, E15 officially by the manual. Sheetz Unleaded 88(Blue Handle, E15) runs better than 87 in my opinion, with better behavior in the heat.

 

[LokiWolf]

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

Jason, Sorry for the delayed response. I just don't get on here as often as I used to.

That -1 is momentary, as in that instance in time. There is a learned Octane value to that is taken in to account. Next time you are running 87, go do a hard full throttle pull and watch that parameter. You will see it change. Watch how quickly it does and how far it moves in the other direction. That is because knock is being detected, and it is adjusting on the fly.

I would hate to disagree with LMS, but I often do! They are not the end all be all on tuning. Especially on the EcoBoosts. I have seen the live data on my own Ecoboosts. There is definitely an advantage to be had with Octane over 91. Also like I have preached on here before the biggest difference in preventing knock and timing being pulled, is Ethanol. E10 89 will perform better than E0 93. E10 87, will perform under load almost as well as E0 93.

You want to run cheaper fuel and have a Sheetz nearby, use the Unleaded 88(Blue Handle, E15), currently cheaper than 87, and will run better in the heat. I saw ZERO loss in MPG when I was using it on my 150. Even if there was a 5% loss, the price difference will easily make up for that.

 

[duneslider]

My old dodge 5.9 was super picky about gas. It would throw codes (generally misfire) if I used crappy gas, I had to fill at the big name places like Chevron or it would throw codes. I would think a cat code is more likely to not be gas related, it is possible for o2 sensors to go bad. They generally last a long time but they can go bad.

 

[Soliyou]

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.

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!

 

[fjordexpedition]

As I somewhat expected, the CEL went out on its own. I had no further triggering after the initial light, nor did I have a trigger after filling up with the same exact fuel again. My hypothesis is the sudden switch from 93 to 87 caused a brief emissions change while the engine computer adapted to the change, and then it self corrected. I will still ask them to scan at the dealership tomorrow and see if they can find anything further.

 

[Ellison Brown III]

The man is spot on! Did not even think of that. You would hope he would notice the sound difference.

If it wasn’t there he would know the second he started it for the first time…

 

[Ellison Brown III]

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.

 

[LokiWolf]

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.

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.