kapk22 Posted May 13, 2021 Report Share Posted May 13, 2021 So, we filled the car up with premium and the dash said it has 273 miles until empty. Then we filled it with regular and it showed 319 miles until empty. why would it be less with premium? Quote Link to comment Share on other sites More sharing options...
Perblue Posted May 13, 2021 Report Share Posted May 13, 2021 It's an estimation based on your previous mpg, which is affected by numerous factors, or current mpg if you reset it. It's more important what you actually got. How you're thinking it would actually be the mpg from the premium that is possibly making it think it can go farther on the next tank even though you put in regular. Now you may go just as far on regular but that takes several consecutive tanks of each to determine that. 1 Quote Link to comment Share on other sites More sharing options...
todd92 Posted May 13, 2021 Report Share Posted May 13, 2021 The car has no idea what octane you just put in. 93 does not get more or less MPG than 87. The counter is based on recent MPG history and assumes your future driving will be similar. 1 Quote Link to comment Share on other sites More sharing options...
niceonept Posted May 13, 2021 Report Share Posted May 13, 2021 (edited) 4 hours ago, kapk22 said: So, we filled the car up with premium and the dash said it has 273 miles until empty. Then we filled it with regular and it showed 319 miles until empty. why would it be less with premium? When you first filled the car it estimated your range based on your pervious driving, not the fuel you put in it - it has no way of knowing that. The second time you filled it, the car still had no idea what fuel you had put in but again based its estimate on your previous driving i.e. when you drove on a full tank of premium. This gave you a higher range estimate - could be because the last tank was premium but could also be other factors such as less city driving, or a combination of both. Edited May 13, 2021 by niceonept 1 Quote Link to comment Share on other sites More sharing options...
omar302 Posted May 13, 2021 Report Share Posted May 13, 2021 Actually, the PCM can determine what type of fuel is in, because the knock sensors detect knocking and adjust timing based on the what it finds. That is why modern engines, Ford's EcoBoost included, make more power on Premium (93) than it makes on regular fuel. This is even listed in the owners manual and Ford's brochures when advertising engine output numbers. Nevertheless, it wouldn't (can't?) do it just by filling it up. What others posted above is probably the reason, the only other exception I can think of is if the cars battery was disconnected for any reason between both fill ups as that would also reset the average mpg on which the distance to empty calculates. 2 Quote Link to comment Share on other sites More sharing options...
Perblue Posted May 13, 2021 Report Share Posted May 13, 2021 3 hours ago, omar302 said: Actually, the PCM can determine what type of fuel is in, because the knock sensors detect knocking and adjust timing based on the what it finds. That is why modern engines, Ford's EcoBoost included, make more power on Premium (93) than it makes on regular fuel. This is even listed in the owners manual and Ford's brochures when advertising engine output numbers. Nevertheless, it wouldn't (can't?) do it just by filling it up. What others posted above is probably the reason, the only other exception I can think of is if the cars battery was disconnected for any reason between both fill ups as that would also reset the average mpg on which the distance to empty calculates. Yes it can but it still can't calculate your mileage from the octane it detects after just filling up. It will say the same dte in accessory, before it even has a chance to figure the octane rating out, as it does when starting it up immediately after filling so it is all based on your mileage history in the pcm. 1 Quote Link to comment Share on other sites More sharing options...
jmr061 Posted May 13, 2021 Report Share Posted May 13, 2021 9 hours ago, kapk22 said: So, we filled the car up with premium and the dash said it has 273 miles until empty. Then we filled it with regular and it showed 319 miles until empty. why would it be less with premium? Fill up with premium, shows 273...meaning it is basing DTE off the previous tank driving habits Then fill up with regular after the premium tank and now showing 319 DTE which is based off your premium tank. Granted it may or may not be attributed to octane as many other factors come into play (driving habits, weather including wind, temp, etc) So it seems right to me. 2 Quote Link to comment Share on other sites More sharing options...
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