View Full Version : Analysing vag-com plots - maf/intake pressure

27-05-2009, 02:16 PM
After some weeks, I have apparently cured a problem with intemittent overboost - probably caused by a sticky VNT actuator or lightly coked vanes (some plus-gas on the actuator overnight and/or a long run cured the problem)

Before I packed away all my stuff, I thought it would be worthwhile to do another VAG-COM plot.

I have done so and it is interesting to note that there is still a certain degree of excess boost and excess MAF compared to spec when accelerating. The spec Intake pressure for example peaks at 2340 and actual values can reach 2600. Under ths same load, MAF is spec 850, actual 1100.

I am pondering that this within normal range as the system is not a fully closed loop control, but am interested to know how closely the actual and spec values should track one another.