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

[fjordexpedition]

I have been running 93 octane fuel since the vehicle was new (about 1 year). In my head, turbo vehicles always use premium fuel, and that is what we always put in since new. I happened to be looking for something unrelated in the owners manual, and saw that 87 fuel is fine. Since it is nearly $1 a gallon cheaper currently where I live, I figured why not use it instead if all I am getting is a little loss of power. That evening, check engine light came on. Unfortunately I cannot find my scan tool at the moment, but in the Ford App, it says that I have an issue with my catalytic converter.

Two questions for the forum. 1) Does it seem logical that using 87 suddenly instead of 93 has caused a check engine light? 2) Are the messages in the Ford App actually accurate to a specific cause, or is that a generic message? For instance, if it was actually a misfire, would it indicate a misfire.

I already have an appointment with the dealer next week for many other issues I am having with the vehicle, so I am definitely taking it in, but I was just curious if anyone had any thoughts in the meantime.

 

[rob4092xx]

I have never run anything but 87 in my 2018 Expy. Never a problem.

 

[JasonH]

I used to use premium only while towing and drove daily on 87. Never had any issues. I wouldn't trust anything in FordPass. It's garbage IMO.

I'm currently on a 700 mile trip with my camper. I blended 87 and 93 down to 91 to save a few bucks. I think it worked out to 7 to 10 per tank. The vehicle isn't tuned to take advantage of anything over 91.

 

[fjordexpedition]

Thanks for confirming 87 should not be an issue. My only thought was maybe the computer had set the timing based on the 93 fuel for so long, and then got some knock with the sudden addition of 87 fuel, and tripped the check engine light, but has probably since pulled timing. I have never seen this with any other vehicle though, even a vehicle that required premium, but I had to put 85 octane in once because I was in the middle of nowhere and that is all they had.

 

[Rob6805]

The messages for the CEL in the Ford Pass app are vague at best. Get a scan tool and find out what the actual codes is.
It certainly seems strange that as soon as you switched to a lower octane the light came on.
And I have run both 93 and 87 in mine at different time. Lately I have been running 87 due to the cost (FJB).

 

[Rob6805]

Thanks for confirming 87 should not be an issue. My only thought was maybe the computer had set the timing based on the 93 fuel for so long, and then got some knock with the sudden addition of 87 fuel, and tripped the check engine light, but has probably since pulled timing. I have never seen this with any other vehicle though, even a vehicle that required premium, but I had to put 85 octane in once because I was in the middle of nowhere and that is all they had.

This is a likely scenario.

 

[rob4092xx]

Exactly why I have always ran 87…..cost. Even more so now with the cost of gas…..FJB.

 

[LokiWolf]

Let's correct a few incorrect assumptions in some of these answers.

Rated power is set based on a industry standard fuel that is equivalent to ~92 Octane, not 91. Notice I said fuel, because it is not gasoline. It is used by most manufacturers now so there is a standard. It is used for MPG, and Power ratings stated by the manufacturer.

Will the EcoBoost make more power with Stock tuning on 93 vs 91, YES! One more time for those in the back. On Stock tuning the EcoBoost motors in the 15+ Expeditions will make more power on 93 vs 91. You could even argue that they will make more power on 95 Octane vs 93, but the returns start to diminish quickly because the stock mapping just doesn't give enough, because the tuning is based on Torque demanded. That more power is going to be even more noticeable under heavy load or high temps, because of the additional Octane it will pull LESS timing as the intake charge temp increases, because there will be less knock.

Normal timing adjustments due to knock being sensed due to Octane changes from 93 to 87, WILL NOT cause a check engine light. The motor simply detunes/pulls timing, and demands less power. Also to be clear, the motor does not tune up to 93, it detunes to 87. It is important to understand that difference. It wants the higher, and settles for the lower, not the other way around.

If you got a Cat Error, with no other errors, it might actually be the CAT's. If you got it with a misfire or other similar code, maybe just a bad tank of gas? Like others said, a real scantool could shed light on that based on stored codes.

 

[dgq68]

Not trying to be funny, but peak under your truck to make sure the cat is still there. Living in NY, they are stealing them like crazy right now.

 

[LokiWolf]

Not trying to be funny, but peak under your truck to make sure the cat is still there. Living in NY, they are stealing them like crazy right now.

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