Hello,

I have been searching to find info on this problem. The car is a
Mitsubishi Space Star 1.3 16 V 1999.

Normal consumption averaged 6.2 l / 100 km. After a while, but
suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
km. And this on average and instantaneous rate.

A fill up at the gas station confirmed the figure from the onboard
computer.

Does anyone know how this consumpton is calculated, and could this mean
a sensor has gone faulty ?

The odometer has no significant fault, only 10 %, which would not
explain the problem. 

Any help warmly appreciated,

Regards,

Carl

In article , 
carlvc@antwerpen.be says...

> Hello,
> 
> I have been searching to find info on this problem. The car is a
> Mitsubishi Space Star 1.3 16 V 1999.
> 
> Normal consumption averaged 6.2 l / 100 km. After a while, but
> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> km. And this on average and instantaneous rate.


<rest snipped>

Causes of poor fuel consumption include (in no particular order):

1) Failed / failing lambda sensor (also known as oxygen sensor).  See 
http://www.picotech.com/auto/lambda_sensor.html

2) Incorrect tyre pressures

3) Failed thermostat - does the engine get up to operating temperature 
OK?

4) Failed temperature sensor - if it gets to the right temperature, does 
the engine managament system know it?

5) Binding brakes - do any of the wheels feel far hotter than they 
should?  Does the car "Lurch" to a halt, or gently glide to a stop?

6) Fuel leak - should be obvious by the smell! (But I guess if the 
computer is showing poor economy this is not the case for you..)

and finally, and most obviously

7) Forgetting to remove roof-rack, trailer or caravan ;-)

Ian
-- 
Ian Riches
Bedford, UK

"Ian Riches" wrote


> > Normal consumption averaged 6.2 l / 100 km. After a while, but
> > suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> > km. And this on average and instantaneous rate.
>
> Causes of poor fuel consumption include (in no particular order):
> ...


In this case it's not poor fuel consumption,
it's an exceptional good fuel consumption.


> > Does anyone know how this consumpton is calculated,
> > and could this mean a sensor has gone faulty ?


If a fill up at the gas station confirms the onboard computer,
it's probably not faulty.

Don't touch the perfectly running system!

Thomas

Ian Riches (ianriches@hotmail.com) gurgled happily, sounding much like they 
were saying :


>> Normal consumption averaged 6.2 l / 100 km. After a while, but
>> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
>> km.

> Causes of poor fuel consumption include (in no particular order):


Umm, Ian...

6.2l/100km is 45mpg
5l/100km is 55mpg
4l/100km is 70mpg.


> And this on average and instantaneous rate.


So this is the economy that the trip computer's reporting? Personally, I 
think the computer's lying through it's teeth...

(I presume it isn't *really* doing 70mpg? If it is, find the problem, and 
bottle it. You'll make your fortune.)

In article <d8m8k7$hhh$1@ginkgo.she.de>, thomas.schaefer@akademische.de 
says...

> "Ian Riches" wrote
> 
> > > Normal consumption averaged 6.2 l / 100 km. After a while, but
> > > suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> > > km. And this on average and instantaneous rate.
> >
> > Causes of poor fuel consumption include (in no particular order):
> > ...
> 
> In this case it's not poor fuel consumption,
> it's an exceptional good fuel consumption.


Ooops.  Teach me not to read properly and confuse my l/100km with mpg.

In that case, look for air leaks.....

Ian
-- 
Ian Riches
Bedford, UK

In article , 
toomany2cvs@gmail.com says...

> Subject: Re: fuel consumption enigma
> From: Adrian 
> Newsgroups: alt.autos.mitsubishi, rec.autos.tech, uk.rec.cars.maintenance
> 
> Ian Riches (ianriches@hotmail.com) gurgled happily, sounding much like they 
> were saying :
> 
> >> Normal consumption averaged 6.2 l / 100 km. After a while, but
> >> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> >> km.
> 
> > Causes of poor fuel consumption include (in no particular order):
> 
> Umm, Ian...
> 
> 6.2l/100km is 45mpg
> 5l/100km is 55mpg
> 4l/100km is 70mpg.


I know.  Blame confusion of l/100km and mpg, not being used to people 
complaining about *improved* fuel economy and publically embarassing 
lack of comprehension skills.

I suspect one of those may be more to blame than the others.

Oops.

Ian
-- 
Ian Riches
Bedford, UK

Ian Riches (ianriches@hotmail.com) gurgled happily, sounding much like
they were saying : 


> not being used to people complaining about *improved* fuel economy 


<snort>

A definite rarity...

"carl"  wrote in message 
news:1118739292.855499.39450@g49g2000cwa.googlegroups.com...

> Hello,
>
> I have been searching to find info on this problem. The car is a
> Mitsubishi Space Star 1.3 16 V 1999.
>
> Normal consumption averaged 6.2 l / 100 km. After a while, but
> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> km. And this on average and instantaneous rate.
>
> A fill up at the gas station confirmed the figure from the onboard
> computer.
>
> Does anyone know how this consumpton is calculated, and could this mean
> a sensor has gone faulty ?
>
> The odometer has no significant fault, only 10 %, which would not
> explain the problem.
>
> Any help warmly appreciated,
>


Pop your spark plugs out and have a look at them to see if there are signs of it 
running lean.

The fuel consumption is normally calculated with the injection time on
this injector by the ECU. The fuel consumption is given as frequence
signal to the computer. This is most of the system anyway.

A really good fuel consumption can mean a lot of thing, from the ecu
calculating wrong to a computer problem. As your engine is still
running fine, I do not thing that the ECU is gone.

I will personnaly tip on a signal problem betwwen the ECU and the
computer. This could be chekced by any good repair shop.

Another possible problem is the mileage of the injectors. In some
cases, large mileage injector tends to inject far much more than
normal. Therefore the ECU will correct the injection volume by dropping
the injection time, reducing the calculated fuel consumption. However,
you will see it on your gas exhaust measurement, normaly the Nox, COx
and HC are exploding !

Well I will recommend you to have your electric system checked !

Regards

Jerome Douay
www.Team74.com

It is really easy to figure out what is telling you stories.

Just fill it up and drive 100 km then fill it again to see what real
life says to compare to the computer's BS.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

carl wrote:

> 
> Hello,
> 
> I have been searching to find info on this problem. The car is a
> Mitsubishi Space Star 1.3 16 V 1999.
> 
> Normal consumption averaged 6.2 l / 100 km. After a while, but
> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> km. And this on average and instantaneous rate.
> 
> A fill up at the gas station confirmed the figure from the onboard
> computer.
> 
> Does anyone know how this consumpton is calculated, and could this mean
> a sensor has gone faulty ?
> 
> The odometer has no significant fault, only 10 %, which would not
> explain the problem.
> 
> Any help warmly appreciated,
> 
> Regards,
> 
> Carl

Hi all,

I'm sorry I did not reply sooner.

Thanks for all of these replies.

As I stated, the fuel consumption at fill up is the same low level, and
I am not sure that I checked against highway mileposts. But as the tach
meter indicated only 10% off truth, I will have to check the odometer
separately.

Today my valves were found to be a bit loose stemmed, but they were too
tightly stemmed at the low level of consumption. And consumption has
not gone up tremendously after the first correction nor the one today.

The spark plugs aren't showing lean mixture signs.

The ECU could be in error, but on the other hand, it has for every
problem double checks, parameter checks and warning codes. None of
these have been found pointing to something. A definite rarity indeed.

I will have to find a non-sceptical mechanic, who is willing to look
and find ...

Thanks again for your replies.

Carl

carl wrote:


> Today my valves were found to be a bit loose stemmed, but they were too
> tightly stemmed at the low level of consumption. And consumption has
> not gone up tremendously after the first correction nor the one today.


Perhaps someone's nicked your wheels and replaced them with smaller ones.

did you turn the AC on?

"carl"  wrote in message 
news:1118739292.855499.39450@g49g2000cwa.googlegroups.com...

> Hello,
>
> I have been searching to find info on this problem. The car is a
> Mitsubishi Space Star 1.3 16 V 1999.
>
> Normal consumption averaged 6.2 l / 100 km. After a while, but
> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
> km. And this on average and instantaneous rate.
>
> A fill up at the gas station confirmed the figure from the onboard
> computer.
>
> Does anyone know how this consumpton is calculated, and could this mean
> a sensor has gone faulty ?
>
> The odometer has no significant fault, only 10 %, which would not
> explain the problem.
>
> Any help warmly appreciated,
>
> Regards,
>
> Carl
> 

If everything else is OK, re-check your tire pressure.

" dojj"  wrote in message 
news:d93s8c$f2s$1@news6.svr.pol.co.uk...

> did you turn the AC on?
>
> "carl"  wrote in message 
> news:1118739292.855499.39450@g49g2000cwa.googlegroups.com...
>> Hello,
>>
>> I have been searching to find info on this problem. The car is a
>> Mitsubishi Space Star 1.3 16 V 1999.
>>
>> Normal consumption averaged 6.2 l / 100 km. After a while, but
>> suddenly, fuel consumption lowered, starting at 5 l to even 4 l / 100
>> km. And this on average and instantaneous rate.
>>
>> A fill up at the gas station confirmed the figure from the onboard
>> computer.
>>
>> Does anyone know how this consumpton is calculated, and could this mean
>> a sensor has gone faulty ?
>>
>> The odometer has no significant fault, only 10 %, which would not
>> explain the problem.
>>
>> Any help warmly appreciated,
>>
>> Regards,
>>
>> Carl
>>
>
> 

No. And it would rather push consumption upwards.

No. And it would rather push consumption upwards.

?
huh

 wrote in message 
news:1119439175.094069.88980@o13g2000cwo.googlegroups.com...

> No. And it would rather push consumption upwards.
>