Bad Fuel Consumption

[JAYMZ]

Hey all,

Just asking on behalf of my dad.

He has a problem with his AU III as all of a sudden his fuel consumption is hitting close to 19lt/100km. As before it was doing around 12lt/100km.

I have no clue, which is why i have come here for any advice or suggestions if this may have happened to you.

Lucky he doesn't have to pay for fuel but still.

Maybe its a sensor or something is blocked etc. It maybe a coincidence but it started doing this when we got the car back from just being serviced.

Any help would be appreciated.
Jaymz.

[WindsorXR]

Maybe check the O2 sensor in the exhaust, this will cause the computer to see a false reading of lean and then richen the mixture up.

Is the car running really bad as well?
Is there any black smoke given a little rev?

[JAYMZ]

No none of this is happening, everything is running perfect, well besides the fuel consumption.

[Yellow_Festiva]

fuel leak? Staart her up and take a good look all along the lines, as well as within the engine bay.

Do the same cold and warm. May show a small but constant drip that will cause the consumption to seem to skyrocket like yours has.

[Jack91]

Yeah, my car's is around about that much too. I think it has more to do with the way I drive though.

[JAYMZ]

Dont think its a fuel leak as theres no drip marks in the garage floor or at his work. the mechanic hooked up his computer to the car and it said it was running very rich but dont know where.

my dad drives slow and conservative so dont believe its that, car is in perfect condition, only done 60000kms. its like someone has chucked a V8 in the engine bay without us knowing.

[sgt_doofey]

How are you measuring the 19l/100kms? Is it from the trip meter or is it from measurements taking after filling up with petrol?

[JAYMZ]

measurements from filling up.

[Mechan1k]

Originally Posted by JAYMZ

Dont think its a fuel leak as theres no drip marks in the garage floor or at his work. the mechanic hooked up his computer to the car and it said it was running very rich but dont know where.

my dad drives slow and conservative so dont believe its that, car is in perfect condition, only done 60000kms. its like someone has chucked a V8 in the engine bay without us knowing.

If the mechanic said it is running rich ... I'd definitely get the O2 sensor (HEGO sensor replaced).

I'd say it is not reading within range and telling the ECU what the correct air/fuel ratio is ... the ECU then goes into a sort of failsafe mode and dumps a lot of fuel into the mix to reduce leaning out ... hence the running rich and excessive fuel usage.

There was a grup buy on for the O2 sensors ... or it can be bought for about $50-ish from eBay (make sure it is the genuine replacement sensor) ... Ford want an arm and a leg for one).

I had similar issues with mine ... i replaced it and it took a couple of tank fills to get the ECU to relearn the new O2 sensors.

How many kays on your parents' AU?????
As these items really should be replaced ever 100,000km.

[JAYMZ]

Originally Posted by Mechan1k

How many kays on your parents' AU?????

Yeah tell me about it, only 60000 and its a daily driver too.

Thanks Mechan1k for your help ill let him know, if your saying it needs replacing every 100,000kms then it could be something else but ill try this first.

Much appreciated.

[IH8HSV]

Disconnect the battery for an hour or so (over night is best ) to reset the E.C.U.

I did this with my BA when my fuel economy rised for no reason. And it worked a treat.

Some people think doing this is over rated but it helped me out.

If this doesn't work check the obvious like tyre pressures, air con clutch engaged, blocked air filter, vacuum hoses off or loose, plugs and leads.

[ratter]

Get the fuel pressure checked, AU's are known for fuel pressure reg problems

[NC1183]

I've started expriencing (sp) similar problems in my AUII ute, replaced the O2 sensor and tried to reset the ECU, it went alright for a couple of weeks, now its worse than before.

When i changed the O2 sensor i also did a throttle body clean and a clean and re-oil of my K&N air filter.

Any ideas would be most appricated

[IH8HSV]

Originally Posted by NC1183

I've started experiencing (sp) similar problems in my AUII ute, replaced the O2 sensor and tried to reset the ECU, it went alright for a couple of weeks, now its worse than before.

When i changed the O2 sensor i also did a throttle body clean and a clean and re-oil of my K&N air filter.

Any ideas would be most appreciated

This resetting of the E.C.U. is a funny thing.

I noticed my BA ( turbo ) was slowly losing power and the fuel economy getting worse.

After discussions from the knowledgeable people on here, i found out the reason behind it.

My car does country kilometers only. As soon as i leave my driveway its 110km/h until my destination. From what i gather, and advice given, this causes the computer to ''train'' itself to drive like this and adjusts itself accordingly. So when i did manage to drive in the city, the car preformend like a slug. - Not used to the heavy acceleration and the idling for long periods of time. Therfore the increased fuel economy.

After an overnight stay in the city i reset my E.C.U. to prove this theory and was surprised how good it drove the next day.

And old wifes tale??? ...... Maybe! But it works for me!

My point being... Every time the car uses too much fuel or doesn't pick up as good as i would like it too i reset the E.C.U.

[brad`]

its true newer cars AU - upawrds maybe Ef as well not sure, but the ecu decides on the best driving patterns and keeps a constant pattern that way. only way to fix it is to reset it.

miost people tend to do it after purchasing a 2nd hand vehicle so it can relearn the best driving pattern for them.

now i read that some where... not sure where so it might be wrong

[bodes-sh]

it may also be worth changing the coolant temp sensor in the back of the head. if this is not working properly the ecu may also be staying in open loop mode because it thinks the motor is cold. where does the temp gauge on the dash sit? it may also need the thermostat replaced if it's not letting the motor warm up properly. the other things to check would be fuel and air filters...

[IH8HSV]

Originally Posted by bodes-sh

it may also be worth changing the coolant temp sensor in the back of the head. if this is not working properly the ecu may also be staying in open loop mode because it thinks the motor is cold. where does the temp gauge on the dash sit? it may also need the thermostat replaced if it's not letting the motor warm up properly. the other things to check would be fuel and air filters...

Yeah good point.

I forgot to mention this in my last post. A faulty temp sender would cause a spike in the fuel economy.

[V8 EF Fairmont]

Had an issue like this in my EF V8 and in the end couldn't actually track down the problem. I still maintain that it was faulty O2 sensors that were installed however the mechanic said although they weren't spot on they were within certain parameters. I would definitely get these checked.

[JAYMZ]

Looking at these responses, heaps of ideas now i may just go through the list an hope it gets back to normal with resetting the ecu. then i guess replace some things.

Thanks fellow members much appreciated.

[SSVPom]

I replaced the oxy sensor, plugs, air filter and had a full service done on the wife's AU2 Ghia 6 cyl, and it still reads 18-19 l/100km with her gentle driving around town !

This still equates to only 300km MAX per full tank, or at least until the trip computer starts shouting "80kms to go," "80kms to go"....

So, coolant temp sensor - is that an easy replacement job for the average DIY mechanic ?

[IH8HSV]

Do the AU diagnostic test. There is a section in the maintance section on the forums on how to do it. ( I would post a link but not sure how to ).

This should tell you what sensor is not working on your car and therefore causing your bad fuel economy.

You only need a peice of wire and an LED light. I brought one from dicksmiths for $1.20. If you have an old dvd player or washing machine laying around you could pull the LED light out of that.

[mrarmageddon]

I had the same problem with my AUIII.

Had the Oxy Sensor replaced, injectors cleaned...... Nothing changed took it to a Ford Service Centre and the cleaned the Fuel Regulator and has worked perfectly ever since.

[Mr Hardware]

where/what is the fuel regulator?

[ratter]

It's on the rear end of the fuel rail.