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.

 

[LazSlate]

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.

Excellent explanation
Also less timing can cause the fuel to not completely burn and cats do not like this.

Ford recommends a min of 91 even though they say it will run on 87. How accurate is the octane ratings at these gas stations?
Also higher outside temps and towing you will notice a big difference in octane rating and performance.

 

[JasonH]

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

 

[Retiredusps]

I would only buy prem. if it was the only thing available. delivered gas for 20 years, palm was greased many times, cross dropped by accident!!! Dealers are known to pump product over at night.

 

[fjordexpedition]

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.

Very good point. I had actually thought of that first, and checked to make sure they are there.

 

[fjordexpedition]

On another note, I appears these messages in the ford app are indeed specific based on this thread I found.

Catalytic Converter Warranty - Just FYI

My engine light came on, so I stopped by my local auto parts shop to have them check the code real quick (for free), and it came back as a catalytic converter issue. When I stopped by Ford to speak to them about it (showed them the photo I took from the code reader after they told me I would...

www.expeditionforum.com

 

[Tmg115]

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.

 

[lobsenza]

I run 87 and never had an issue. Plenty of power. I cannot justify the additional cost of 93 octane.

 

[keny01998]

I use 89 when the gas wasn't expensive and I use 87 now. Notice I lost about 2 mpg but it's offset the price.

 

[LazSlate]

When I started running 93 in all my cars I notice they naturally ran better but the maintenance went way down.
My 2010 Ford E350 Van has always ran 93 and no issues at 200k for sensors, cats, etc. Been a bullet proof vehicle.

 

[LazSlate]

I use 89 when the gas wasn't expensive and I use 87 now. Notice I lost about 2 mpg but it's offset the price.

The mileage lost could also be the fuel not fully burning due to the timing retardation and this is bad for the cats and o2 sensors in the long run.