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View Full Version : How should I analyze this VAG-COM log?...



audi_dude
02-05-2008, 10:48 PM
Been trying to diagnose an occasional stumbling problem when driving (with some large unusual swings on my wideband AFR gauge), so I got a VAG-COM, read enough of the manual to get some logs, and was able to find the measuring blocks for air mass and a few other parameters.

When the car is running properly, mass air values are around 4-5 g/s, but as soon as the problem develops (usually "switches on" noticeably rather than fading gradually into the problem) mass air values doubles right away.

Here's a quick snippet of the log showing the transistion. But I notice that the throttle angle changes as well, but I am not touching the accelerator here. Is this indicative of some other problem, or does this truly represent a problem with the mass air?

Car is B5 1.8T FWD, btw.

Thanks!



ECT, O2 Correction, RPM, Air Mass, Throttle Angle
97.5 0 880 5.14 6.5
97.5 3.1 880 5.07 6.5
97.5 -2.3 880 5 6.5
97.5 -7 840 5 6.5
97.5 0 880 4.93 6.1
97.5 -2.3 840 5 6.5
97.5 -6.3 840 4.86 6.5
97.5 -4.7 840 5 6.5
97.5 0.8 880 5 6.1
97.5 -2.3 840 4.86 6.5
97.5 -6.3 840 4.79 6.5
97.5 -10.9 840 5 6.5
97.5 -3.1 840 5 6.5
97.5 0.8 840 5 6.5
97.5 -6.3 840 5.07 6.1
97.5 -11.7 760 8.89 7.4
97.5 -18 880 11.59 6.5
97.5 -3.1 800 10.9 7.8
97.5 0 800 12.01 8.2
97.5 0 800 11.94 8.7
97.5 0 800 12.15 9.1
97.5 0 960 11.18 8.7