Ok so here is the BIG QUESTION and it pertains to Ford Fiesta MPG.

[Sometimes1needhelp2]

I have had this vehicle for almost 2 years now there is a little over 103,000 miles on her she runs great considering she is about 13 yrs old now but she has been taken care of well I noticed when I 1st bought this Fiesta that I was receiving my 40 mpg like it was advertised which is why I bought it so now today I am only seeing 32 and sometimes city mpg now there were a few times I did see it reach to 36 and 37 on the highway and I suppose it is very normal to be receiving 28 and 32 city all the time and never 40 city would I be correct on this ? I keep thinking I should see it reach 40 in city but maybe no to this ? I also heard that depending on how old the car is it will not be receiving 37-40 much longer ? But I also replaced spark plugs myself it has a 750 battery in it now there should be nothing to hinder the vehicle from receiving the best city and best all around mpg correct ? Also if I am to ever start receiving worse and worse and worse mpg would I then need to replace the fuel pump or ECG because the TCM had already been replaced do to a rock flying up in there in smacking it.

 

[Handy Andy]

Have you done any ALIGNMENTS since you've purchased the vehicle?

Checked Tire Pressures?

Brakes? Have they been recently done?

How about the "junk in the Trunk" - extra cargo your car doesn't need to go with you?

Those are some limiting factors.

Rolling Resistance, Power to Weight ratios.

You also have to look as the "recovery" of the MPG.

In a Fixed gear system, like a manual transmission, the fuel economy is a set point more consistent with the efficiency of the torque to speed relationship. A given amount of power delivered to the wheels by the vehicle as you shift thru the gears - those gearing ratios and the volume of air/fuel needed to make it accelerate - and even keep the same speed - varies with load, but also is consistent with the fixed gearing - you're only going to get so much out of the MPG than you'd have coasting and otherwise using different ratio gearing.

This is where automatics tend to show their efficiency but by different gearing than you'd have with a fixed manual system.

Autos also use fixed gears but have a converter to transfer torque and rational speed to transfer energy into motion.

CVT's use something similar to Automatics but use a simpler transfer case system where larger pulley to smaller pulley changes are then switched - one side, on acceleration the pulley uses the torque, (small end) the other tries to get rotation from it (larger end) - when the speed increases - the pulleys configurations are dynamic, one side that was large, gets smaller, while the other side that was small, gets larger - so the ration of one aspect changes as the torque improves to transfer power between the two.

The slippage of the low-end gearing in automatics, affects torque and speed but as the "turbine" of the auto collects speed, the ability of it to TRANSFER torque into motion changes, the conversion improves - it has a gear ratio on the upper end of gearing that tends to make it effective, not efficient - at getting up to that speed, but the efficiency comes from the RPM to wheel rotation - that ratio on the top end of an automatic transmission is where it shines.

CVT - means continuously variable transmission (some cars are simply this pully system like an old motor bike would use) connects to an automatic transmission to help transfer rotational speed once the torque for "getting up to speed" is lessened and now can cruise

You and your car can suffer bad MPG numbers from jackrabbit starts and a lot of junk in the trunk getting hauled around - affecting any sort of efficiency - and it's worse with automatics - keep it light and simple - in any car or vehicle. And it will show vastly higher MPG due to the weight to power ratios the engine has, to bring it up to speed as efficiency.

It's the brining it up to speed is where manuals do better than Autos and CVT's

But CVT's have that better ratio of rotation torque and autos are second best - but their losses are heavy - when you're heavy. Simply put, the heavier you are, or your car doesn't roll very well - the worse this effect is.

The above has to be said because once the MPG "I once got" is going down, too many other variables come into play to blame the car, it can be from the driving style and conditions you drive in too.

 

[scotman]

That is a multi pronged question. Other members can weigh in because i might be missing something relevant!
In my experience with Fiesta, front wheel bearings are issue number one on every Fiesta with more than 45,000 miles on it. Rear bearing failure is much rarer because of the simple fact that they don't carry around much weight. The exception being people who haul lots of cargo. They will also see shorter rear brake life.
The reason for front bearing failure is not just miles, it's heat. The wheel bearings and hub are a heat sink for the front brakes and also soak up the constant intrusions of the stability controls that give us such a stabile, planted feel when we are driving down the highway. That "feel" comes from almost constant "nibbling"of the stability controls.
Short version of the story is that wheel bearings getting tight as they age are a huge amount of the loss of fuel economy.
Number two fuel economy killer is incorrect tire pressures. I will toss in wheel balance right next to that.
Number three is air filter element conditon and airbox cleanliness. I don't think that i need to get too deep into that subject.
Number five.Wheel alignment. Fiesta's don't seem to have many issues with that until tie rods and various bushings become worn out.
Number six is motor oil. The recommended grade in a full synthetic type is very desirable. A good quality brand filter or Motorcraft is best.
The rest are a mix of factors depending upon the level of scrutiny the owner chooses to apply in regards to maintenance of spark plugs and wireset, upper intake manifold and throttle body cleaning regimen, oxygen sensors primarily the bank 1 sensor 1 or upstream O2, replacing that one at around 60k really helps prolong the life of the catalyst as a side benefit of better fuel economy. And last would be the fuel itself. Cheap fuel with lots of ethanol is not the best, or even good, fuel to choose. It's just poor, from a BTU perspective.
I' m sure i missed something that the other members can weigh in with.

 

[Sometimes1needhelp2]

So I can't keep a manual scissors tire jack in my car or a set of jumper cables that are in it's case in the car and my tire iron ? I just have all of my safety gear things in the back end or as you would say junk in the trunk but this isn't to much is or is it ? I have snow tire chains in the back end copper chains for if I get stuck in the muddy water or snow is this to much ? Thank you.

 

[LionsTooth]

I have 87k on mine. I don't haul a bunch of stuff most of the time. I change the oil every 3-5 k miles....clean my K& N when it looks dirty ( every 5-7 miles. especially during fire season here when the air is like mud). I just did 407 miles of twisty coastal road and some highway and averaged out at 36.5 MPG. I can get 40 on the highway if I stay at or below 70; not likely across CA, NV, UT & WY to my dad's house a couple of times a year. On those trips, I spend the majority of the time at or above 80 and average about 34-38 depending on the wind (and I carry about 200 extra pounds of luggage and such). I take good care of my car so that may have something to do with it. Also, I roll most stops at stop signs because I know coming to a complete stop is a gas suck. YMMV!

 

[Sometimes1needhelp2]

So sitting at a Rapid City red light forever will hinder my mpg ? lol.

 

[LionsTooth]

So sitting at a Rapid City red light forever will hinder my mpg ? lol.

And you never get where you're going!

 

[Sometimes1needhelp2]

Yeah you need a hang glider or a helicopter when it comes to getting around in Rapid fricking City SD lol and these streets these streets lol.

 

[Sometimes1needhelp2]

and the drivers over are REALLY CARELESS and really bad about 94% of them and they don't care if they wreck into you and that is very sad and dangerous and reckless.

 

[Sometimes1needhelp2]

That is a multi pronged question. Other members can weigh in because i might be missing something relevant!
In my experience with Fiesta, front wheel bearings are issue number one on every Fiesta with more than 45,000 miles on it. Rear bearing failure is much rarer because of the simple fact that they don't carry around much weight. The exception being people who haul lots of cargo. They will also see shorter rear brake life.
The reason for front bearing failure is not just miles, it's heat. The wheel bearings and hub are a heat sink for the front brakes and also soak up the constant intrusions of the stability controls that give us such a stabile, planted feel when we are driving down the highway. That "feel" comes from almost constant "nibbling"of the stability controls.
Short version of the story is that wheel bearings getting tight as they age are a huge amount of the loss of fuel economy.
Number two fuel economy killer is incorrect tire pressures. I will toss in wheel balance right next to that.
Number three is air filter element conditon and airbox cleanliness. I don't think that i need to get too deep into that subject.
Number five.Wheel alignment. Fiesta's don't seem to have many issues with that until tie rods and various bushings become worn out.
Number six is motor oil. The recommended grade in a full synthetic type is very desirable. A good quality brand filter or Motorcraft is best.
The rest are a mix of factors depending upon the level of scrutiny the owner chooses to apply in regards to maintenance of spark plugs and wireset, upper intake manifold and throttle body cleaning regimen, oxygen sensors primarily the bank 1 sensor 1 or upstream O2, replacing that one at around 60k really helps prolong the life of the catalyst as a side benefit of better fuel economy. And last would be the fuel itself. Cheap fuel with lots of ethanol is not the best, or even good, fuel to choose. It's just poor, from a BTU perspective.
I' m sure i missed something that the other members can weigh in with.

Will cleaning or changing my fuel filter or cleaning my fuel injectors improve mpg in a big way because I have not done either of these things for over a year now. Thanks.

 

[Sometimes1needhelp2]

Will cleaning or changing my fuel filter or cleaning my fuel injectors improve mpg in a big way because I have not done either of these things for over a year now. Thanks.

 

[scotman]

We don't have a serviceable fuel filter
It is built into the pump assembly.
As for injector cleaning, i usually just run a couple tanks of high detergent premium fuel like Mobile drive clean or Amoco Silver twice a year. Theres a thread in the forums on fuel additives.
I like Seafoam or Lucas products. But, there are other's.

 

[scotman]

So I can't keep a manual scissors tire jack in my car or a set of jumper cables that are in it's case in the car and my tire iron ? I just have all of my safety gear things in the back end or as you would say junk in the trunk but this isn't to much is or is it ? I have snow tire chains in the back end copper chains for if I get stuck in the muddy water or snow is this to much ? Thank you.

Safety equipment, seasonally appropriate gear and tire service tools should always have a place. Just use your own judgement. You know what you are comfortable with.
Some people have no issues traveling across the country with nothing more than a clean pair of underpants and a pack of Doublemint gum.

 

[Handy Andy]

Hmmm, you posts read as if you are angry over the issue of other drivers - the poor MPG and what someone can do

So, this is a multi-pronged question with several issues in each "prong".

So, apologies to you without truly knowing what you were asking.

But now that we know.

It can pretty much be presumed that "safety gear" like the tire iron, it's jack and even the limited-service spare - you need to keep these in there.

Seems odd that you suddenly bring up the removing these items, when you got good mileage before - with them still in there (unless you took the out when you first bought the car - not a good idea if you are not sure of the vehicles integrity when you are still new to the cars handling)

Here's where I apologize for the junk in the trunk references, I was referring to other service items like blankets and the bags of salt you may have kept in there when you drive the vehicle in winter - those are unnecessary to carry in the summer, so prudence and good judgement play the roles here.

Even if ...

• does the Ice Scraper stay in there? No, but if needed it can help remove those stubborn bug-remains that don't otherwise wash off easily with the squeegee.
• Water bottles? Always a good idea when stranded, or even to get you back on your way. An overheating condition can harm the motor - you may not have radiator fluid around - but water can help offset the loss of coolant - at least two or three bottles of simple 16oz size can give you extra time and mileage to get you to safety when the engine is cool enough to touch the cap - you can remove the cap and just use the water straight from the bottle - twofold - it's filtered, and water is used in the coolant anyways - just it dilutes the mixture but it can help you top off the amount so you can drive to safety.
• Wrenches? That is not the needed go-to all the time, but a simple set of tools - even pliers and vise grips, can offset and augment the tire iron and jack, for when the need arises - you may find replacing the tire can't be easily done - because the WHEEL is FROZEN to the hub and the two won't separate easily - that's where a heavy tool like the vise grips can provide the leverage to hold the wheel while you pry and hammer to loosen it from the hub.

So, to me, the loss of MPG may be more related to the AC, or lack of true driving versus waiting at a light for it to change.

Do you have a No Turn On RED option? Where some intersections - instead of waiting for that light to "sense" you and change, the State law may allow for turn on RED as long as you yield to cross and oncoming traffic - that way a simple right turn then keeps you moving and keeps the MPG calculator working - think UPS drivers, those Brown trucks - they schedule and fuel limits are pretty tight - so they make the most of moving efficiency - dealing with turns and not having to be waiting at lights for turns. Time is money. So is the Gas used during that time. So, if you can find a route that lets you make turns without having to wait so long, affects the MPG.

I guess this really boils down to - keep moving to keep the Odometer turning while the engine turns - the more efficient you are at this method, the better the MPG.

My MPG issues come from matching speeds for other drivers in multi lane roads and city street traffic lights, so that "city driving" idiom applies to my efforts of trying to keep moving and not waiting too long for lights to change or have to drastically accelerate to match and keep up with traffic trying to get to work of home - that simply wastes gas but it is also a NECESSARY function to help remember to keep in timing of those lights so you don't find yourself becoming a speed bump from others that have to rush home to go pee.

Weight? Yes, it can play a role if alignments are needed and or the brakes or tires are worn, but as far as engines efficiency - the AC and drive habits are more important - comfort versus a rolled down window - between the two - the rolled down window usually wins - unless it's raining, or the heat is so bad that AC is needed because your own health and safety becomes the main concern.

Worn spark plugs show up in 60,000 miles, a plugged air filter sooner than that - usually a good inspection habit is to open the hood and take the top of the air cleaner (or airbox as some may call it) to take out and tap the filter to loosen any loose dirt and caked material from the filter media - and if you can see light thru its pleats - then you can consider it safe to use for another season - until Fall or until Spring - every 6 months, just don't neglect it - out of sight out of mind kind of thing can leave the car on the side of the road - which doesn't do you any good.

 

[Handy Andy]

To me, this is why it's important to keep an eye on your cars battery.

It can affect Fuel mileage due to a "reset" that may occur during a power down sequence that was not completed because the BATTERY Monitor function engaged while it was still powering down. The Voltage from the battery dropped faster than the system was expecting - so it simply went down due to the rapid drop - and the I/M monitors or any sort of emissions testing - never completes the cycle.

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When you speak of MPG, the issue around the efficiency of the system, comes into play.

IN the older carbureted systems, they used a predetermined size of orifice - called a "jet" and small tapered rods called a Needle slid up and down within the orifice of that jet - with the throttle angle, (Often, this is referred to as Needle and Seat)to change the amount of fuel brought into the air mixture thru the Venturi principle - which was helped along by another sub-system called Accelerator Pump - a small piston moved in sync-with and with an eccentric, to help move more fuel into the airflow to improve the power delivery that depended on the throttle angle - but by only so much - to help with acceleration and the vacuum drop from engine load changes.



So to develop proper efficiency the system needs air to move the injector spray into the combustion chamber - so it needs air to carry it in to move the charge to make the system work - a minimum RPM is needed to pull this into the combustion chamber - that is your lowest RPM to prevent lugging.

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