MAF test results

[richandhazel]

Did a test of my MAF sensor today with VAGCOM. This was the best run, full throttle up a dual carriage, 4th gear, changing to 5th:-

RPM   MAF   MAF   EGR
          Req   Act

2541   770   760   4.8        4th gear accelerating up hill
2604   850   770   4.8
2667   850   850   4.8
2751   850   825   4.8
2814   850   790   4.8
2898   850   775   4.8
2961   850   765   4.8
3045   850   770   4.8
3087   850   770   4.8
3150   850   765   4.8
3213   850   765   4.8
3276   850   765   4.8
3339   850   750   4.8
3402   850   755   4.8
3465   850   740   4.8
3528   850   740   4.8
3591   850   735   4.8
3654   850   740   4.8
3717   850   735   4.8
3780   850   725   4.8
3822   850   725   4.8
3885   850   715   4.8
3150   810   590   4.8
3087   850   1005   4.8    Change to 5th gear and continue accelerating up hill
3087   850   1005   4.8
3108   850   685   4.8
3129   850   660   4.8
3129   850   670   4.8
3129   850   675   4.8
3150   850   690   4.8
3150   850   705   4.8
3171   850   720   4.8
3171   850   735   4.8
3192   850   745   4.8
3192   850   750   4.8
3213   850   750   4.8
3234   850   750   4.8
3255   850   755   4.8
3276   850   760   4.8
3297   850   755   4.8
3318   850   755   4.8
3339   850   745   4.8
3360   850   750   4.8
3381   850   750   4.8
3423   850   745   4.8

This is the test:

At 3000 rpm full load (test can only be done while driving) the reported air intake quantity should be at least 800 mg/stroke

It looks like my MAF is not reaching 800 and therefore requires replacement.

Just wondered what peoples thoughts are and whether you think that the MAF is sufficiently underperforming that it will make a big difference to overall performance.

[GazB]

Just keep it in 5th while accelerating up a hill

[paul25_uk]

Can you do the MAF test with the free version of VAGCOM, as that's all I have?

[richandhazel]

Not sure if you can do it with the free version. Mine is fully registered.

Incidentally, for future reference, I changed the MAF sensor and haven't really noticed any difference. I would conclude that although the sensor was underperforming and probably going bad, it wasn't bad enough to cause any noticeable difference at this stage.

Therefore those figures will need to look a lot worse before you notice a drop in performance and need to change it.

[Rhyso]

you can measure your MAF readings with the free version 

me and a mate tried it out on my 130 the other day; couldn't make head or tail of the results though!! though it looked like my MAF was doing the job  

Only annoying feature is that it only records the information for 3 minutes and then resets with a message telling you to buy the full version!!

Might have to invest in that next year as the free version made me realise how cool VAG COM is

[richandhazel]

If you've got someone with you, makes it a lot easier. Even with what you are saying about the free version, as long as your mate is monitoring the results that should suffice to prove/disprove the MAF operation.

The actual MAF should get somewhere near to the required MAF. As you can see from my results, mine was a little low but obviously not bad enought to warrant changing.........even though I changed it anyway

[Rhyso]

I'll have to have another go and post up the results; gives me an excuse to open her up 

From what i remember the actual MAF readings were well above what was required ; I'll have to dig out my last results to double check 

Did you get your VAG COM direct from Ross Tech?

[richandhazel]

No, I bought mine from a colleague at work. He sold his VW so passed the software and lead on to me.

I'd be interested to see your results.

[Rhyso]

what measuring blocks did you use when testing the MAF? Just want to be sure I'm measuring the same blocks so as to give an accurate comparison.

But this is what was recorded previously.  However, it was just playing about and not keeping it in one gear.

Engine speed   MAF (specified)   MAF (actual)
790-870            230-310             210-350
                           /min    mg/str    mg/str
1659                             355              382.2
1638                             250              470.4
1617                             260              333.2
1617                             290              284.2
1617                             315              318.5
1638                             430              401.8
1659                             455              450.8
1680                             435              455.7
1680                             300              298.9
1659                             250              480.2
1638                             250              499.8
1617                             265              396.9
1617                             330               328.3
1617                             320              308.7
1617                             265               264.6
1596                             250               460.6 - this amazes me because it's well over the required limit!! 
1575                             250               494.9
1554                             250               494.9
1533                             250               504.7 - twice as much!!

only posted a fraction of what was recorded but you get the picture.  My question is though; is my car overfuelling?? 

[richandhazel]

Revs are too low and what gear were you in?

Need to put the engine under load, 4th gear accelerating hard, foot to the floor stuff