B6 A4 Tdi MAF

[stevewr1]

Hi folks, my 1st post here but been hanging around a while, great forum. Could anybody with experience with VCDS examine my MAF readings to see if my MAF is bad. My car is a 04 B6 A4 Tdi Sport AVF engine.

The car seems to be down on mpg and im unsure if its the MAF to fault, I done the 3rd and 4th gear roll ons with VCDS and logged, Ive included a link to the CSV file or readings are below if they can made out! Thanks in advance

http://expirebox.com/download/a32a95ccbd3a3ed9c594688ee809aaa3.html

Engine speed MAF (specified) MAF (actual) EGR duty cycle
TIME 790-870 230-310 210-350 40-75% TIME
Marker STAMP /min mg/str mg/str % STAMP
0 882 250 230.3 57.4
0.29 882 250 245 57
0.63 882 250 245 57.4
0.99 882 250 245 57.4
1.33 882 250 245 57.4
1.68 861 250 240.1 57.8
2.04 882 250 249.9 57.8
2.39 882 250 240.1 58.2
2.74 882 250 245 58.2
3.1 861 250 249.9 59
3.46 882 250 254.8 59
3.81 882 250 235.2 59
4.16 861 250 245 59.4
4.52 882 250 249.9 59.8
4.88 882 250 235.2 60.2
5.23 882 250 245 59.8
5.59 882 250 240.1 60.2
5.95 882 250 249.9 60.2
6.31 882 250 245 60.6
6.67 882 250 245 60.6
7.04 882 250 240.1 60.6
7.39 882 250 230.3 60.2
7.75 882 250 215.6 59.8
8.11 882 250 245 59.4
8.47 861 250 249.9 59
8.82 882 250 264.6 59.4
9.19 1092 850 387.1 4.8
9.54 2037 850 445.9 4.8
9.9 2877 310 617.4 39.8
10.25 2583 280 504.7 4.8
10.6 2058 755 475.3 63
10.96 2961 850 646.8 4.8
11.31 4599 850 891.8 4.8
11.66 4662 850 529.2 4.8
11.99 3843 850 529.2 4.8
12.33 3108 320 499.8 4.8
12.66 2583 280 480.2 4.8
12.98 2079 270 499.8 62.6
13.3 2436 850 543.9 4.8
13.63 3759 850 808.5 4.8
13.94 4872 850 725.2 4.8
14.27 4116 850 534.1 4.8
14.6 3423 345 524.3 4.8
14.94 2793 295 494.9 4.8
15.28 2268 280 504.7 58.2
15.62 1785 270 367.5 70.1
15.96 1386 250 279.3 71.3
16.31 966 250 200.9 68.9
16.65 924 250 220.5 62.2
16.99 882 250 176.4 56.2
17.34 882 250 230.3 51.8
17.68 882 250 249.9 52.6
18.04 882 250 259.7 53.8
18.39 882 250 264.6 54.6
18.74 882 250 254.8 55
19.08 882 250 264.6 55.4
19.43 861 250 254.8 56.6
19.78 882 250 259.7 56.6
20.13 882 250 254.8 57.8
20.48 882 250 254.8 58.6
20.84 882 250 245 59.8
21.19 882 250 240.1 60.2
21.55 882 250 249.9 60.6
21.91 882 250 240.1 61
22.25 882 250 245 61.4
22.61 882 250 240.1 61
22.97 861 250 245 61
23.34 903 250 235.2 60.6
23.69 882 250 249.9 60.6
24.05 882 250 235.2 60.6
24.41 882 250 235.2 60.2
24.77 882 250 235.2 59.8
25.12 882 250 225.4 59
25.47 882 250 220.5 59
25.83 882 250 245 58.6
26.18 882 250 235.2 58.2
26.52 882 250 230.3 57.8
26.87 861 250 235.2 57.4
27.2 861 250 225.4 57
27.54 882 250 235.2 57
27.86 882 250 225.4 56.6
28.18 882 250 245 56.2
28.5 882 250 235.2 55.8
28.82 882 250 235.2 55.8
29.13 882 250 240.1 55.4
29.44 882 250 235.2 55
29.76 882 250 245 54.6
30.1 882 250 249.9 55.4
30.43 882 250 235.2 54.6
30.76 882 250 235.2 54.6
31.08 882 250 235.2 54.2
31.41 882 250 225.4 54.2
31.74 882 250 230.3 54.2
32.08 882 250 230.3 53.8
32.42 882 250 245 53.8
32.75 882 250 254.8 53.8
33.09 882 250 245 53.8
33.44 882 250 249.9 53.8
33.8 882 250 245 54.2
34.16 882 250 240.1 54.2
34.5 882 250 245 54.2
34.86 966 595 249.9 24.3
35.2 882 545 294 57.4
35.54 1197 845 406.7 4.8
35.89 1365 315 490 4.8
36.25 1407 410 519.4 4.8
36.61 1260 250 548.8 60.2
36.97 861 250 240.1 66.5
37.32 882 250 210.7 62.6
37.67 882 250 196 59.8
38.03 882 250 200.9 55.8
38.38 882 250 220.5 53
38.74 882 250 254.8 52.2
39.09 882 250 259.7 53
39.45 882 250 249.9 53.4
39.8 882 250 235.2 53.8
40.15 882 250 259.7 55
40.49 882 250 249.9 55
40.85 882 490 245 55.8
41.21 1197 275 377.3 51.4
41.56 1176 285 421.4 4.8
41.91 1050 410 465.5 45.8
42.25 1071 390 338.1 44.2
42.6 1092 415 426.3 42.6
42.94 1218 390 441 46.2
43.25 1344 490 421.4 37.9
43.58 1491 505 568.4 35.9
43.89 1659 505 573.3 45.4
44.2 1785 495 441 41.8
44.53 1785 270 485.1 57.8
44.84 1428 250 294 57.8
45.15 1050 465 490 4.8
45.48 1113 615 494.9 19.9
45.82 1197 660 539 4.8
46.15 1302 755 612.5 4.8
46.49 1428 690 646.8 4.8
46.83 1554 655 695.8 19.9
47.17 1659 645 779.1 27.1
47.52 1785 635 823.2 43
47.86 1848 425 632.1 66.5
48.21 1848 270 352.8 83.3
48.55 1512 250 328.3 84.5
48.9 1029 250 205.8 82.1
49.26 903 250 176.4 76.1
49.6 903 250 156.8 68.9
49.96 903 250 181.3 61.8
50.3 882 250 151.9 52.6
50.66 882 250 235.2 51.4
51.01 882 250 264.6 52.6
51.36 882 250 254.8 53.4
51.72 882 345 264.6 54.2
52.08 1134 260 338.1 50.2
52.43 1113 360 445.9 48.6
52.78 1113 350 298.9 48.2
53.14 1113 365 313.6 46.2
53.48 1134 415 377.3 42.2
53.85 1176 465 460.6 39.8
54.2 1239 555 490 4.8
54.56 1323 770 534.1 4.8
54.92 1428 775 646.8 4.8
55.28 1575 760 735 4.8
55.64 1722 745 837.9 4.8
56 1848 720 911.4 24.7
56.35 2016 740 1004.5 4.8
56.72 2142 700 1053.5 44.6
57.07 1974 270 470.4 76.1
57.4 1554 260 352.8 82.1
57.74 1176 250 200.9 4.8
58.07 1470 360 490 4.8
58.41 1407 375 548.8 4.8
58.72 1428 400 558.6 4.8
59.04 1449 465 578.2 4.8
59.36 1449 470 622.3 48.6
59.68 1470 475 431.2 39.8
59.99 1512 545 583.1 4.8
60.31 1554 685 705.6 4.8
60.63 1596 570 739.9 31.1
60.97 1638 490 499.8 50.2
61.32 1659 380 450.8 62.2
61.67 1659 330 338.1 63.8
62.01 1701 330 303.8 65.7
62.34 1701 355 284.2 59
62.68 1701 330 274.4 53.4
63.02 1722 365 338.1 49.8
63.37 1701 280 362.6 55.4
63.72 1722 270 318.5 61.8
64.06 1701 270 289.1 63.8
64.41 1680 270 269.5 64.9
64.76 1701 270 259.7 64.9
65.12 1659 270 254.8 64.1
65.47 1638 270 249.9 63.4
65.82 1638 270 245 63
66.17 1617 270 249.9 62.2
66.53 1596 270 249.9 60.6
66.87 1575 260 249.9 59.4
67.23 1533 255 225.4 58.6
67.59 1218 250 259.7 58.6
67.95 861 250 171.5 57.8
68.31 882 250 225.4 53.4
68.67 882 250 249.9 53.8
69.02 903 250 259.7 54.6
69.39 882 250 264.6 55
69.74 882 250 249.9 56.2
70.1 882 250 249.9 57.4
70.46 882 250 254.8 58.2
70.82 882 250 245 59
71.18 882 250 259.7 59.4
71.53 882 250 249.9 60.2

 

[desertstorm]

The MAF looks good to me, At idle it's around 250, it's difficult to tell how much load the car is under just looking at what you have logged but at times I can see what looks like acceleration runs especially around 400-600 Seconds and the specified and actual look OK with the MAF hitting 1050-1100 mg/str values.
I would be looking else where. How many MPG is the car doing and how long have you owned it. some peoples expectation of mpg are not in line with what the car is capable of. Is it standard or does it have mods, larger wheels/ tyres etc don't help mpg.

Karl.

 

[stevewr1]

The MAF looks good to me, At idle it's around 250, it's difficult to tell how much load the car is under just looking at what you have logged but at times I can see what looks like acceleration runs especially around 400-600 Seconds and the specified and actual look OK with the MAF hitting 1050-1100 mg/str values.
I would be looking else where. How many MPG is the car doing and how long have you owned it. some peoples expectation of mpg are not in line with what the car is capable of. Is it standard or does it have mods, larger wheels/ tyres etc don't help mpg.

Karl.

Thanks for your reply karl,

I have the car about a year and its standard with no modifications. Car was giving me over 50mpg under normal driving conditions. I recently changed the fuel filter (aftermarket) and strangely since then I have noticed a decrease in mpg to around 36-38mpg.

Also recently the temperature gauge was also only reading 70 degree so I changed the thermostat and the gauge is now reading 90 degree. I also recently cleaned the intake and egr valve and serviced it with a new air filter(genuine), oil(castrol turbo diesel 5w 40) and oil filter. Still giving low mpg's

Im thinking now it might be the coolant temp sensor but VCDS is not showing a fault code, is there a way to diagnose the temp sensor with VCDS?

 

[desertstorm]

Have you refitted the fuel pipes correctly, you haven't got a leak anywhere have you ?. Diesel is not so obvious as it doesn't smell as much as a petrol leak.
Coolant temp can be seen in the measuring blocks, Check that it looks like a reasonable value.

Karl.

 

[stevewr1]

Have you refitted the fuel pipes correctly, you haven't got a leak anywhere have you ?. Diesel is not so obvious as it doesn't smell as much as a petrol leak.
Coolant temp can be seen in the measuring blocks, Check that it looks like a reasonable value.

Karl.

Yeah I definitely refitted the fuel lines correctly and im quite sure there are no leaks elsewhere but ill give the car a good look over again and update. Cheers karl

 

[mattyb6]

Are the injectors furling fine on vcds?
Check the synchro angle while your at it, m/block 4 iirc

The tandem pump isn't weeping diesel is it?

I'm assuming there's no faults since you've already used vcds

 

[stevewr1]

Are the injectors furling fine on vcds?
Check the synchro angle while your at it, m/block 4 iirc

The tandem pump isn't weeping diesel is it?

I'm assuming there's no faults since you've already used vcds

Yeah there are no faults showing on VCDS, ill check out what you mentioned, cheers matty

 

[stevewr1]

Well guys went away and bought a new genuine coolant temperature sensor. 51 euros..nearly dropped!! Fitted it and took the car out and covered 95 miles, Massive improvement..gauge needle hardly moved! I think its working out about 50 odd mpg again..happy days!!

Car has 140k genuine miles so maybe the sensor was never changed as it was a genuine black sensor and looked rough. Strangely though on VCDS the coolant tempature was bang on 90 when warmed up with the old sensor. Thanks for the suggestions karl & matty!