Possible cause of poor gas mileage: front grill shutter vanes improperly operating

[Dude]

Saw this recent post, it’s for a 1.5L but I would guess same issue could apply to 2.0L.

“Poor fuel mileage, about 17-18mpg on a brand new ‘23 (1.5L), dealer of course asked about my driving habits and fuel. I said that’s not the problem I drive like a grandpa lol. This is what they found, MPGs are in the high 20s to low 30s now.”

VARIOUS GRILLE SHUTTER FINS/VANES POPPED OUT NOT IN CORRECT POSITION.. NECESSARY TO REMOVE GRILLE SHUTTER ASSEMBLY/LINKAGE FOR FURTHER INSPECTION..
NECESSARY TO REMOVE COOLING MODULE PER WSM.. FOUND VANE BEARINGS NOT CLICKED IN ALL THE WAY.. PROPERLY INSTALLED OUT OF PLACE VANES AND INSTALLED VANE BEARINGS.. GRILLE SHUTTERS NOW MOVING AS DESIGNED.. REINSTALLED AND RETESTED GRILLE SHUTTERS MOVE AS DESIGNED.. ROAD TESTED VEHICLE APPROX 20 MILES.. AVERAGED 31.9 MPGS IN ECO MODE CITY AND HIGHWAY SPEEDS.

Sponsored

 

[sajohnson]

“Poor fuel mileage, about 17-18mpg on a brand new ‘23 (1.5L), dealer of course asked about my driving habits and fuel. I said that’s not the problem I drive like a grandpa lol. This is what they found, MPGs are in the high 20s to low 30s now.”

It's not possible that the grill shutters alone made that much difference in the mileage.

+1-2 mpg, maybe, but for an increase of 13-14 mpg there must be more to the story.

 

[Dude]

It's not possible that the grill shutters alone made that much difference in the mileage.

+1-2 mpg, maybe, but for an increase of 13-14 mpg there must be more to the story.

Nothing more than as reported by the tech according to the person that posted the issue with its fix. Post #1 shows what the tech stated. doubt we will see more info.

That being said, I did not see how such a large fuel economy drop could occur but the engine control computer must really be over compensating by consuming gasoline!!

I agree with your post but in general i take what owners say at face value, neither agreeing nor disagreeing. My gut feel is there is more to the story however.

 

[gatornek]

It's not possible that the grill shutters alone made that much difference in the mileage.

+1-2 mpg, maybe, but for an increase of 13-14 mpg there must be more to the story.

I'm almost certain also.

Saw this recent post, it’s for a 1.5L but I would guess same issue could apply to 2.0L.

“Poor fuel mileage, about 17-18mpg on a brand new ‘23 (1.5L), dealer of course asked about my driving habits and fuel. I said that’s not the problem I drive like a grandpa lol. This is what they found, MPGs are in the high 20s to low 30s now.”

VARIOUS GRILLE SHUTTER FINS/VANES POPPED OUT NOT IN CORRECT POSITION.. NECESSARY TO REMOVE GRILLE SHUTTER ASSEMBLY/LINKAGE FOR FURTHER INSPECTION..
NECESSARY TO REMOVE COOLING MODULE PER WSM.. FOUND VANE BEARINGS NOT CLICKED IN ALL THE WAY.. PROPERLY INSTALLED OUT OF PLACE VANES AND INSTALLED VANE BEARINGS.. GRILLE SHUTTERS NOW MOVING AS DESIGNED.. REINSTALLED AND RETESTED GRILLE SHUTTERS MOVE AS DESIGNED.. ROAD TESTED VEHICLE APPROX 20 MILES.. AVERAGED 31.9 MPGS IN ECO MODE CITY AND HIGHWAY SPEEDS.

This wouldn't trip a CEL, but it would leave a DTC for sure. This is an easy check with an OBD2 dongle.

 

[ZQ8]

I have unplugged shutters before on a car and yes it did turn on the CEL on it. A 2014 ATS.

 

[gatornek]

I have unplugged shutters before on a car and yes it did turn on the CEL on it. A 2014 ATS.

I've done it on my Mustang. No CEL. But there is a DTC. I imagine all Ford PCM's are probably similar. Maybe.

 

[Dude]

In the owners case, the shutters didn’t fail and were not unplugged but were stuck due to improper assembly. Don’t know if that would cause a CEL or a DTC. I’ll ask the owner but nothing about that was mentioned by the owner or the tech.

Also, if it was very warm, having shutters stuck closed would likely cause the temperature gauge to rise.

My temp gauge stays at 4 bars for in town driving (with instantaneous fuel economy displaying typically under 20mpg for in town traffic) and drops to 3 bars on the freeway at 60-65mph (with instantaneous fuel economy displaying typically 35-40+ for level roadways). Outside temp is 100-110°F.

 

[Dude]

The owner with the issue (see Post #1) stated no CEL came on. Didn’t know if tech saw DTC but nothing was stated by the tech in the write up shown in Post #1. The owner said he had no indication of an issue other than seeing 17-18mpg on a new ‘23 (1.5L) with 1,900 miles.

Anyway, doesn’t seem like problems with the front grill shutters have been reported often so likely the issue with the shutters is rare (is my guess).

 

[Dude]

Pretty good article on how active shutter systems work. Not specific to any one vehicle but has sections on various vehicles, the Ford F-150 section is interesting and does state a DTC would be stored if the software detects an issue with shutter movements during calibration following engine start up.

For F-150, also states: active grille shutter system is primarily used to maximize fuel economy by reducing aerodynamic drag, and to shorten engine warm-up time. But doesn’t say how much the fuel economy is improved.

Other articles say active grill shutters improve fuel economy 0.5% to 1.5% and based on that
do not support the owners claim in Post #1 of fuel mileage improving from 17-18mpg to high 20s to low 30s mpg.

Have to call B.S. on the owners claim lol

https://www.vehicleservicepros.com/service-repair/article/53083885/servicing-active-shutter-systems

 

[Mwittke5857]

It's not possible that the grill shutters alone made that much difference in the mileage.

+1-2 mpg, maybe, but for an increase of 13-14 mpg there must be more to the story.

I removed the shutters on my 21 BB and gained a mile per gal

 

[Mark S.]

I removed the shutters on my 21 BB and gained a mile per gal

There's more to this. You cannot INCREASE drag and IMPROVE fuel economy at the same time unless something else also changed.

Sponsored