(Focus Mk2.5) How To Deal With Horrible Fuel Economy?

[Colin449]

Hi everyone! I've recently acquired a 2005 Focus [sedan :( ] with a 1.8 Duratec HE engine and I'm slowly working on getting it to run right. When I bought it, it wasn't running well at all - been parked under a tree for almost two years. The engine ran rough, idle fluctuating at stop lights, plus the check engine light came on after I limped the car home from the guy I bought it from.

I bought myself one of those cheapy OBD-II scanners that connects to my phone and it told me that I was getting misfires. I changed out all the spark plugs and replaced the ignition coil on that one cylinder that was misbehaving and the problem vanished.

Other things done to the car so far are:

• Changed all 4 brake pads. Fronts were worn out and one of the rear ones was sticking.
• Changed oil and oil filter
• Changed air filter
• New tires (same size, brand and tread as originals)
• Interior detailing (Car was very clean inside when I bought it, but still. xD)

Despite all of those things, I've been getting really crap fuel economy on the car. With a light foot on the throttle almost all of the time, it's only giving me 7 - 8 Km/L (18-ish MPG). Engine sounds fine and pulls really well. It's a ton of fun when you floor it on a highway.

If it makes any difference, the car's a 4-speed automatic with a sequential shift option. I've enlisted the help of my dad who's a mechanic, but he's a bit old school - doesn't quite understand cars with ECUs.

Can anyone point me towards new things I can try to get that fuel economy up?

[IINexusII]

are you looking at the average mpg? or the instant?

being automatic it would probably make a big difference compared to manual

[Colin449]

I'm basing this off of the in-dash readout, but I've done the traditional way as well. I filled up the tank, reset the trip counter and ran it till the fuel light came on. The in-dash readout was off, but not by much.

Yeah, I figured the automatic transmission will give me less fuel economy compared to a manual one, but 18 MPG is still terrible. Honestly, I'm at a loss at what to check. The engine runs smooth now, no odd noises, no loss of power, no problems at all.

It's funny how my dad's `07 Explorer with a V6 gets the same fuel economy as this car does.

[SeanW]

I have the same engine - I'm getting around 30mpg (rough calculation) around town with roof bars on

[Invisible Man]

I too have the same engine and around town MPG varies quite a lot.

If I go into the City i get about 30mpg when the weather is warm, around 25mpg is it's cold.

Where I live is quite hilly and when it is warm I get around 26mpg and around 22mpg when it's cold.

I would say that I do a 50/50 split between Urban and Motorway driving and I average 33mpg.

18mpg sounds very low, in fact, I'm sure the 2.5L ST does better than that

[Goodkat]

I get between 20-25, but on a run it will do over 30mpg. My journeys consist of short runs, not getting up to temp for long. I also think I need an air filter change as not sure it was done on last service.

Same engine, manual box.

Sent from my Gen 1 WAP phone

[Colin449]

I live in a tropical country near the equator. It's pretty much warm over here all year long so the car doesn't need long to get into the right temps. Usually, it idles down from a "cold" start in 5 minutes so I don't think temps have anything to do with it.

I drive the car to the countryside a lot so the car sees a lot of open highway and some mountain roads. Nothing too extreme though. I barely have to put my foot down when going uphill. I gas up with Shell's V-Power (not sure about UK equivalents, but it's the best fuel the Shell branches here have on offer so I don't think it's fuel either. It's an automatic too, so it rarely revs to 4K and up.