over fueling

[gazd101]

hi guys wondering if you could give some advice

my mpg  figures on my 115 gt tdi have fallen from 50 ish to nearer 42 im wondering if there is a way to check with vag com if it is overfueling

iv tried looking at my maf and its giving readings which are higher than wot is required is this a sign that my maf is broken or could it be something else?

cheers guys

[richandhazel]

I have been led to believe that its normal for the economy to drop off at this time of year compared with summer. Mine has done much the same.

[gazd101]

really i cant say iv ever noticed the problem before and iv had this car for about three years.

confussed by my MAF readings to cant understand why the figures im getting are higher than whats required does any one know if these figures look about right?

thinking of just putting another MAF sensor on and seeing how the figures compare
            
Engine speed   MAF (specified)   MAF (actual)   EGR duty cycle   
            
            
1512    730   681.1    4.8                                                                 4th gear
1449   250   494.9   4.8   
1344   255   343   52.6   
1239   715   509.6   19.9   
1050   250   494.9   50.2   
1575   745   607.6   4.8   
1659   850   779.1   4.8   
1764   700   857.5   4.8   
1827   620   632.1   52.2   
1848   540   529.2   47.4   
1848   615   681.1   39   
1848   620   592.9   45.8   
1911   535   524.3   49.8   
2016   850   1082.9   4.8   
2163   850   872.2   4.8   
2331   850   911.4   4.8   
2499   850   960.4   4.8   
2646   850   965.3   4.8   
2793   850   970.2   4.8   
2919   850   935.9   4.8   
3045   850   940.8   4.8   
3192   850   921.2   4.8   
2583   850   1029   4.8   5th gear
2646   850   886.9   4.8   
2730   850   926.1   4.8   
2583   250   656.6   4.8
2310   850   852.6   4.8
2352   850   784   4.8
2352   615   666.4   60.2
2310   240   543.9   4.8
2268   240   534.1   4.8
2226   240   539   4.8
2142   240   543.9   4.8
2016   240   529.2   4.8

[Bluefox]

I have been led to believe that its normal for the economy to drop off at this time of year compared with summer. Mine has done much the same.

Yeah, isn't it something to do with the cooler tempreatures having an effect on the density of the fuel? Most systems (including petrol pumps, so I'm told) measure volume as opposed to density.. which has a net result of a system despensing more fuel.

This might be complete rubbish, but let's discuss!

[gazd101]

well thats  certainly a possibility as strange as it sounds
thanks for the help guys

p.s does anyone no if the free version of vac com is capable or reading fault codes or do i need to buy the registered version?

[richandhazel]

I think the free version will read the fault codes. Whether you can clear them or not is another thing.
I'm sure a bit of delving into the Rosstech site will tell you for sure.

[Ridg]

I think the free version will read the fault codes. Whether you can clear them or not is another thing.
I'm sure a bit of delving into the Rosstech site will tell you for sure.

only a similar note, anyone point us in the direction of a cheap cable that works, i bought a USB one from fleaBay and its sh1t, it only works with half the stuff in vag com

[ExEvo]

Just wondering what is vac com.

I don't really seem to get the mpg most talk about what's the best way to test if all okay.
Will a motorway run at a certain mph let me know if i am getting the right mpg.

Cheers
Tim.

[Ridg]

Just wondering what is vac com.

I don't really seem to get the mpg most talk about what's the best way to test if all okay.
Will a motorway run at a certain mph let me know if i am getting the right mpg.

Cheers
Tim.

VAG Com is the name of a piece of software that emulates the Volkswagen diagnostic hardware.

if lets you do certain tests on the ECU, turn stuff on and off eg passenger air bag, check for faults etc

in terms of mpg, if find it varies depending on the weather and the trip as going uphill is going to use more than going down hill.

Personally i'm happy if i get 485 from a tank, but this figure is going to vary depending on what your journeys are like and how fast you drive.

What i do, i reset the 2 trip counter, when i fill up, that way i can see exactly how far i got from that tank, most i've seen is 517, but i'm sure some of the guys with 115 & 130's will have seen more.

What sort of mpg you getting at the moment?

[ExEvo]

Cheers for the replies
Not sure on the mpg , i have not tested it properly yet. Me and the Mrs have have only been doing about 3-4 miles and back and forward from Tesco and her mums house so i suppose it can't quite get going.It goes upto between 30 - 40 by about 2-3 miles is that about right.

Also i have a 3 week old baby and we have been putting her in the back because of the airbags but we can't see her. How can i turn the air bag offs I thought they have switches , not mine that i can find anyway.

Cheers
Tim.