12MPG around town normal?

[11TH GEN]

Check your tires. I find that when my tires get low, gas mileage drops.

Excellent point Frank. With temperature changes even a two or three pound loss per tire can adversely effect MPG.

[Brad]

The higher percentage Ethanol in your gas, the worse your mileage will be

[ChrisTBird]

thanks for the replies guys! my MPG dropped 30% (18 to 12, more or less). our gas has 10% ethanol or less, and tires are fully inflated. thats a huge MPG drop and I don't think it can be all tires/gas/idling, for two full tanks over a month.

thinking that the cops and/or plugs are misfiring which is why I have new ones coming. at least replacing them should rule something out. I am not 100% confident in the amazon cops but usually cheap cops as far as I can tell from other peoples experiences, work fine but just might not last as long.

also glad no one replied about other issues like that the "$900 ecu / johnson rod interface" always does this (and it's unavailable)!

I will definitely report the MPG results from new plugs and cops. :)

[Brad]

Have you changed/cleaned your air filter? Also clean the MAF and intake...a bad sensor anywhere could make your engine run rich

[ChrisTBird]

hmm, I will check filter (cant remember if I ever changed that) and clean the MAF with MAF cleaner spray. But I would think that the O2 sensors would pick up the extra fuel and if it cant be adjusted by the ECU, throw a check engine light?

UPDATE: just bought CRC MAF Cleaner spray at O'Reilly's and cleaned the MAF with it but it was very clean anyway. Could clearly see the element and it had no coating on it. Just a very little dust on the sides. But it was good to have that stuff on the shelf anyway.

[phil]

I purchases the cheap ones from Amazon based on good review. So far they are working great and I ordered an extra set just in case. Not sure why but the one time I get caught in teeming rain the next day the cops were bad?

[Señor Gar]

Personally I would try to establish baseline performance under controlled conditions before spending a lot of money chasing something that may (or may not) be normal for your current operating conditions. I would take a couple of hours, fill the tank, drive 48 miles @ 60 mph in light freeway traffic on cruise control, turn around, return home and fill the tank again. If I used 4 gallons of gas I would assume my car is running fine at 24 mpg (EPA estimate) and current operating conditions are causing the excessive fuel consumption. Maybe stop along the way for a nice lunch and make an outing of your drive.

If you do the highway test and use 6 gallons that would correspond with your 12 mpg around town vs. EPA estimate of 18 mpg. Then maybe there is something that can be 'fixed' and you can continue your investigation.

[Alamobird]

Try a new gas cap. Cured a couple of "Check Engine" lights and improved gas mileage.

[Elky64]

For what its Worth:
Don't know about the Bird yet, but over the last five years, the effect of winter blend (in northern Mass) is at least 10% dropping milage. Our regular drivers are a'15 Accord, '16 Forrester, and previously a '12 Colorado 4 cyl. They all drop milage with the 'winter blend'. At that rate, this winter I would expect the 19-20 that I get around town in the TBird to be about 17, unless the Ford computer setup somehow compensates. The special car I had before the TBird was not very much effected as it was a 64 El Camino with a 400 small block. So it only got about 13 around town and was set up a bit rich anyway.(Old school stuff).
Al

[ChrisTBird]

all great advice thanks! I will do a baseline all-steady-highway test at some point, and replace the cops and plugs and see no matter what since already have them.

[Señor Gar]

all great advice thanks! I will do a baseline all-steady-highway test at some point, and replace the cops and plugs and see no matter what since already have them.

If you engine is not misfiring you might want to save the coils you replace just in case one or more of the new ones give you any concerns down the road. Some members carry them in their vehicle for minimum downtime in remote locations.

[ChrisTBird]

havent done the plugs yet (busy then it got too cold). on recent trip, got about 21/22 mpg. so its off by maybe 10% or so on hwy. will report result after plugs and cops go in.

[ChrisTBird]

Finally installed the Bosch 4419 plugs, and new COPS from Amazon. Took a 1500 mile trip and guess what, toward the end of the trip I noticed the cats getting hot (can hear them tinking when coming to a stop), then got a check engine light - P0300 random misfire (even though it was running fine). Cleared the codes and drove it a few hundred more miles with no light but still occasional hot cats.

After checking the plug wells for oil or water, I am probably going to try the Motocraft plugs from the dealer. Just to rule in or out the plugs.

May not even be plugs or cops but something else but I am leaning toward ignition for now.

Trip MPG was 20 MPG towing a small utility trailer.

[DaiUyTed]

The discussion brings to mind that I've had my 'Bird for eight years; some 30,000 miles. And when someone asks me about it, I'm embarrassed that I haven't the vaguest idea what its fuel consumption is. Never checked! Don't care!
Never used anything but 93 octane, and I'm rarely aware its price. Even back when it was the daily driver.
These are simply insignificant aspects of the overall delightful experience.

(I've had Beetles, and a Honda CVCC; as well as an Eldo convertible and a Trans Am, among many others. Thirstiest was a Chevy Impala. Back then I cared...)

[BLACK BEAUTY]

[QUOTE=DaiUyTed;n1027653]The discussion brings to mind that I've had my 'Bird for eight years; some 30,000 miles. And when someone asks me about it, I'm embarrassed that I haven't the vaguest idea what its fuel consumption is. Never checked! Don't care!
Never used anything but 93 octane, and I'm rarely aware its price. Even back when it was the daily driver.
These are simply insignificant aspects of the overall delightful experience. EXACTLY! my thoughts too