2001 focus 13 mpg.

[zak_kaz]

Hello everyone,

I am trying to diagnose and repair my ex-gfs car. I used to own a taurus that I loved to death, so I know how to work on fords.

 

Vehicle: ford focus 2002 hatchback

 

Symptoms : 13 mpg. This is in town/highway mix about 50/50. Also this is in interior AK, which reduces fuel economy a bit. For comparison I get 37 mpg in the exact same conditions in my 2001 diesel jetta.

 

History: She recently bought the car for 3250. Asked me to check it out before she bought it to make sure she was not making a terrible purchase. Car is clean, nominal cosmetic damage to plastic bumper parts. Seller was a private party, had a binder full of receipts for work done on it, seemed totally legit (I later found out he was flipping the car, bought it for cheap, fixed the idle and sold it for 800 more than he paid for. Had I known he only owned it for 3 weeks I would have been more skeptical, but he was pretty smooth)

 

Performance: the car runs, idles like a healthy car. The only real symptom is that it gets about half the fuel economy it should. It got 16 mpg when she first got it (at about 35-40 f) now it is getting 13 mpg (at about 0 f)

 

Theories : I think it could be the mass air flow sensor, but it could be a combination of things. This car should be getting 25-28 mpg under these conditions. Something is really wrong, but it is not causing any warning lights or a rough idle or any abnormal sounds.

 

I would experiment / test my hypothesis more but I have to get this done and fixed all in one go, not fuck with it for the next week.

Any suggestions would be greatly appreciated and will likely get this boy laid.

 

Thanks ford community,

Zak

[akirby]

If the engine seems to be running ok then I would suspect a mechanical problem with the wheels/brakes or the driveline. Does it coast ok when you put it in neutral? Does it seem to respond to normal throttle input?

 

The other thing to check is the odometer - make sure it's accurate on miles driven.

[zak_kaz]

If the engine seems to be running ok then I would suspect a mechanical problem with the wheels/brakes or the driveline. Does it coast ok when you put it in neutral? Does it seem to respond to normal throttle input?

 

The other thing to check is the odometer - make sure it's accurate on miles driven.

It drives fine. I can coast I neutral without any abnormal speed loss/ resistance.

It has 95k miles on it, and registration and receipts for service done to the car, and the condition of the vehicle are consistent with that number. Regular and intermittent services were done by a professional shop. This car has been better taken care of than anything I have ever owned.

 

The previous owner did have to replace something on account of a rough idle before he sold it, but now it runs fine. I will have to check the service receipts to find out exactly what was done to the car.

 

I am thinking it has to be some sort of issue with how much fuel is being injected or inefficient combustion somehow, but I can't be sure.

 

One other possibly related symptom popped up today - she fuelled up (140 miles on a tank, jeeze) and the fuel Guage was very slow to register and only read a quarter tank after a few minutes.

[akirby]

How are you getting the 13 mpg? Are you calculating it manually or using the dash readout (if it has one)?

 

If the odometer was off and was only registering half the mileage it was supposed to then that would cut your mpg in half - that's why I asked. To test it just drive a 3-5 mile route with one vehicle, measure it then run it again in the Focus to make sure they match.

 

If it was dumping twice as much fuel as normal then it wouldn't be driving normally. The other thing to check is operating temperature - make sure it's warming up properly. If not the thermostat could be stuck open.

[zak_kaz]

How are you getting the 13 mpg? Are you calculating it manually or using the dash readout (if it has one)?

 

If the odometer was off and was only registering half the mileage it was supposed to then that would cut your mpg in half - that's why I asked. To test it just drive a 3-5 mile route with one vehicle, measure it then run it again in the Focus to make sure they match.

 

If it was dumping twice as much fuel as normal then it wouldn't be driving normally. The other thing to check is operating temperature - make sure it's warming up properly. If not the thermostat could be stuck open.

Manual calculation, there is no read out. Fill up tank, reset trip meter, drive until fuel light comes on. Refill, divide gallons put in car by miles on the trip meter. Operating temp seems to be normal according to gauges. Warm up time about 5-10 minutes in the mornings if it is less than 20 degrees f.

Last tank got 140 miles on 12 gallons.

Edit: sorry it took me a minute to understand what you were saying about the odometer. I will track a trip on iphone gps and compare it to the odometer, however I doubt that is the problem because it has the correct size tires and even if she was running oversized rims it should not tank the mpg that bad.

Edited November 19, 2013 by zak_kaz

[YT90SC]

If it runs ok, it is unlikely to be a MAF. They can be cleaned easily and quickly using MAF cleaner. Follow the instructions on the can. I have several ideas like exhaust backpressure, DPFE malfunction, fuel pressure issue etc, but without a scan tool, you are going to be shooting in the dark at this point.

[zak_kaz]

If it runs ok, it is unlikely to be a MAF. They can be cleaned easily and quickly using MAF cleaner. Follow the instructions on the can. I have several ideas like exhaust backpressure, DPFE malfunction, fuel pressure issue etc, but without a scan tool, you are going to be shooting in the dark at this point.

 

Researching scan tools. Thanks for the tip!