MAF vs EGR vs somethign else?

[sjbilton]

Picked up a '02 Alhambra 115 TDi last week, all runs welll - 44mpg Exeter to Bimingham and back at the weekend, but, when at over about half throttle it gets lumpy...

A colleague has VAGCOM so we took it for a quick run at lunchtime and logged this. We're now not sure whether it is the MAF that's goosed or the EGR that needs cleaning out... or deleting.

So using the collective wisdom ... ... ... what's the verdict please? I did try to attach a graph but as a newbie I can't... sorry

Time (s) RPM MAF (Spec) MAF (Actual) EGR Duty %
0 2835 850 931 4.8
0.38 2898 850 950.6 4.8
0.77 2982 850 960.4 4.8
1.17 3045 850 975.1 4.8
1.56 3150 850 965.3 4.8
1.93 3171 850 975.1 4.8
2.29 3234 850 970.2 4.8
2.64 3318 850 965.3 4.8
3 3339 850 960.4 4.8
3.36 3381 785 877.1 4.8
3.72 3297 610 690.9 4.8
4.08 3339 635 553.7 4.8
4.44 3297 610 514.5 4.8
4.8 3276 575 504.7 4.8
5.18 3234 515 494.9 4.8
5.57 3129 410 499.8 4.8
5.96 3024 280 514.5 4.8
6.35 2919 265 519.4 4.8
6.74 2793 265 514.5 4.8
7.13 2667 265 514.5 4.8
7.52 2541 265 514.5 4.8
7.91 2415 265 514.5 4.8
8.3 2268 260 519.4 4.8
8.66 2121 255 514.5 4.8
9.01 1995 255 514.5 4.8
9.35 1848 260 450.8 82.9
9.71 1722 265 313.6 81.7
10.05 1596 265 308.7 84.1
10.42 1449 265 308.7 84.1
10.77 1302 265 298.9 84.5
11.16 1176 260 294 84.5
11.56 1008 270 259.7 84.5
11.95 924 265 240.1 68.9
12.34 903 260 230.3 65.3
12.73 903 260 240.1 64.1
13.12 903 260 249.9 62.6
13.48 903 260 254.8 62.6
13.83 903 260 249.9 62.2
14.19 903 260 254.8 63
14.53 903 260 259.7 63.8
14.89 903 260 249.9 63.8
15.23 903 260 249.9 63
15.59 903 260 264.6 63.4
15.95 903 260 264.6 63.4
16.31 903 260 249.9 63.4
16.67 903 260 245 63.4
17.05 903 260 254.8 64.1
17.44 903 260 249.9 63.8
17.83 903 260 259.7 64.1
18.22 903 260 254.8 63.4
18.61 903 260 254.8 64.1
19 903 260 254.8 64.5
19.39 903 260 249.9 64.5
19.78 903 260 254.8 65.3
20.17 903 260 249.9 65.3
20.52 903 260 259.7 64.9
20.88 903 260 245 66.1
21.24 903 330 328.3 46.6
21.6 987 475 475.3 31.9
21.95 1029 530 480.2 20.7
22.3 987 570 494.9 19.9
22.66 1197 605 465.5 19.9
23.04 1449 790 504.7 4.8
23.43 1764 805 553.7 4.8
23.81 2100 785 637 19.9
24.21 2457 790 739.9 19.9
24.6 2688 440 788.9 50.6
24.99 2415 265 573.3 4.8
25.38 1659 705 607.6 24.7
25.77 1680 850 661.5 4.8
26.12 1827 850 725.2 4.8
26.48 1974 850 784 4.8
26.84 2142 850 852.6 4.8
27.2 2310 850 891.8 4.8
27.56 2478 850 926.1 4.8
27.92 2604 850 813.4 42.6
28.27 2730 850 872.2 43
28.63 2856 825 877.1 43.8
29.01 2982 850 852.6 43.8
29.4 3129 850 911.4 4.8
29.78 3234 740 901.6 4.8
30.17 2898 260 681.1 4.8
30.56 2100 250 597.8 4.8
30.95 2163 515 592.9 39.4
31.34 2079 540 553.7 51.4
31.73 2142 700 612.5 46.2
32.1 2184 850 769.3 37.1
32.45 2268 850 842.8 4.8
32.81 2310 850 916.3 4.8
33.17 2415 850 950.6 4.8
33.53 2457 850 970.2 4.8
33.89 2499 850 1004.5 4.8
34.25 2604 850 999.6 4.8
34.61 2667 850 1029 4.8
34.99 2730 850 1073.1 4.8
35.38 2835 850 1058.4 4.8
35.77 2877 850 1078 4.8
36.16 2961 850 1068.2 4.8
36.55 3045 850 1053.5 4.8
36.94 3150 850 1038.8 4.8
37.32 3150 850 1063.3 4.8
37.72 3234 850 1043.7 4.8
38.11 3297 850 1043.7 4.8
38.48 3402 850 1033.9 4.8
38.84 3465 850 1014.3 4.8
39.19 3528 850 989.8 4.8
39.55 3570 850 965.3 4.8
39.91 3612 850 935.9 4.8
40.27 3654 850 891.8 4.8
40.63 3444 785 720.3 4.8
41.01 2646 260 617.4 4.8
41.4 2604 575 641.9 26.3
41.79 2541 560 632.1 52.6
42.18 2562 510 534.1 60.6
42.57 2583 500 494.9 60.6
42.96 2583 360 445.9 73.3
43.35 2583 285 357.7 84.5
43.7 2583 275 313.6 84.5
44.04 2583 270 294 84.5
44.4 2583 270 264.6 84.5
44.75 2562 270 254.8 84.5
45.11 2562 265 259.7 84.5
45.46 2541 265 245 84.5
45.82 2541 270 245 84.5
46.17 2520 270 245 83.3
46.52 2520 275 245 74.9
46.87 2541 285 254.8 63

Thanks

Steve

 

[k123]

Blinded by numbers but looks alright I think.

You can see If the EGR is fouled up or not by taking boost pipe off and shining a torch in there.....just before you take it apart!!!!

Maybe fuel filter if its at higher revs? A bit of starvation going on?

 

[cypher007]

you could always use vag-com to software delete the egr and test if it runs better.

 

[sjbilton]

you could always use vag-com to software delete the egr and test if it runs better.

Would I still need to blank off the EGR pipework or would just switching it off do the job?

Can you on this engine just plug the vacuum hose to achieve the same end result?

Cheers

Steve

 

[cleverspoon]

By turning it down you reduce the amount it opens.....which i understand is good because it still functions to aid in warm up times but greatly reduces the amount if exhaust gas which is let in.
Ideally you want to do the logs in 3rd/4th gear on a uphill stretch full throttle.