what to look out for when FC ( fuel consumption ) is high?

[lee5627]

I would like to know what to look for when yr FC goes a little higher. I have a few things that I am aware of and would like to know what you guys ( the experts) thinks. Currently I have a checklist and was wondering what did I miss out....... ( FYI my fc is around 12l/100km or about 8.3 km/litres )

Here is what I know :
1. spark plugs
2. ensure tyres are pumped correctly
3. check fan and engine belts
4. engine oil
5. air filter
6. yr style of driving
7. % of travelling on Highways and % start-stop traffic
8. Traffice Jams :-( ** Best culprit - it sucks up the most petrol **)

Pls add if you know other factors as well.
Thank you very much for yr kind replies and expert advices!

 

[Davidwee]

9. Install V-Kool
10. Turn off aircon at night

 

[lee5627]

actually I was referring to where something could be wrong!

There was a time where my fan belt is almost on the verge of breaking and somehow this is causing my FC to go higher. Luckily for me cos i have been monitoring, i went to check out engine compartment and voila....the fan belt is almost breaking.....

after change of belt, FC is back to normal

 

[Racebred]

pumping the wrong grade of petrol.

and in fact malfunction of any component in your drivetrain which could affect the efficiency of energy transfer, from your torque converter, gearbox, damaged/not lubricated wheel bearings, faulty rear differential, stuck brake calipers, and also mis-aligned wheel settings.

 

[BorisRS]

....and in fact malfunction of any component in your drivetrain which could affect the efficiency of energy transfer, from your torque converter, gearbox, damaged/not lubricated wheel bearings, faulty rear differential, stuck brake calipers, and also mis-aligned wheel settings.

Actually was wondering about this. My E39 is really sucking gas. I average around 18-19.5l per 100km on the car which is admittedly driven largely around bukit timah and into town. This is actually higher than the beast which gives me a reading of around 17-18l per 100km. I also notice that the car is running rich cos there is plenty of carbon deposit at the exhaust. Any suggestions? :screwedu:

 

[Whisky_Tango]

Points from Racebred are valid as worn or misalign mechanical parts contribute to additional loading(other than the car & passengers weight and road gradient loadings) and inefficiency.

Other factors I can think of are

1) Aged or dirty sensors (MAF, Oxygen, engine oil temp)
2) Clogged fuel injectors which does not produce atomization effect
3) Fuel adaptation (suggest you reset the ECU and monitor the FC for next 3 tanks.

Cheers!

 

[Whisky_Tango]

Actually was wondering about this. My E39 is really sucking gas. I average around 18-19.5l per 100km on the car which is admittedly driven largely around bukit timah and into town. This is actually higher than the beast which gives me a reading of around 17-18l per 100km. I also notice that the car is running rich cos there is plenty of carbon deposit at the exhaust. Any suggestions? :screwedu:

Hi Leslie

Did you advance the ignition timing of the E39?

 

[Racebred]

you're talking about the M5 right? this consumption is very good liao. i'm doing 22L/100km or 4.5km/L on my 4.2L, and that's on totally KUNIANG driving. any bringing of revs above 5000rpm, the consumption goes up to 25L/100km, or 4km/L. dont complain liao lah leslie. heheheeheh

 

[louis]

Racebred,

4km/L? oh goodness... now i know why my neighbour's always driving so slowly... haha, and i thought he just wanted to hao lian.

 

[E46]

Windows up when travelling 80 and above. Aerodynamically wise penalise a small percentage

 

[BorisRS]

you're talking about the M5 right? this consumption is very good liao. i'm doing 22L/100km or 4.5km/L on my 4.2L, and that's on totally KUNIANG driving. any bringing of revs above 5000rpm, the consumption goes up to 25L/100km, or 4km/L. dont complain liao lah leslie. heheheeheh

Buy italian exwhoretic lah! Guess we are all allowed to make a mistake at least once :laughing:

what really worries me is the black carbon at the exhaust tip. If I use a cloth and wipe away, macham black soot...

WT,

Have not done anything to the car. 100% stock.

except for short shift kit....

 

[Shaun]

Try comparing the vehicle masses. Mass is a very large factor esp in all driving outside of pure highway cruising.

 

[Racebred]

eh les, go and dyno your car lah. then you can also watch the AFR readings from there see if you're running too rich.

but of course it only shows you the AFR on WOT

 

[BorisRS]

eh les, go and dyno your car lah. then you can also watch the AFR readings from there see if you're running too rich.

but of course it only shows you the AFR on WOT

You sound as if you want me to measure how bad my fart smells......I would love to get both cars dynoed---starting with Beastie. Maybe can arrange to do it one day soon...just been so damn busy!

 

[Shaun]

RB, you can still see part throttle AFRs on the dyno.. just go to part throttle. Matters not if it is loading or inertia type.. both can do it.

Do one power pull and then do a part throttle exploration.. no need to log the run or print it.. just watch the wideband and see the rough range of light-mid load AFR.