Factory BOSCH MAF vs Pierburg test

[piko]

Hi!

I have an interesting find to share.
Here is a datalog of MAF voltage and boost vs rpm.
Both third gear same conditions, above is NEW BOSCH and bellow is the New Pierburg factory replacement.
What is interesting is the distinctive BOSCH voltage drop between 5400 and 5600rpm. It drops from 4.7 to 3.9V which causes a lean flatspot.
The Pierburg Maf doesn't seem to suffer at the same conditions. What you see is the MAF sensor output signal. The signal is then clamped at 4.6V with AEM piggyback but that doesn't matter in this case.
http://shrani.si/t/2F/qg/2iftORR8/pierburboschmaf.jpg (http://shrani.si/?2F/qg/2iftORR8/pierburboschmaf.jpg)

My setup is w202 c200 kompressor (me2.1) 220mm crank pulley and MAF relocation. Max boost in higher gears is 0.82bar.
http://shrani.si/t/2W/HZ/4H5c69eH/14030006.jpg (http://shrani.si/?2W/HZ/4H5c69eH/14030006.jpg)

It is obvious that the sensors have a different design but should both measure flow as factory specified.

It is obvious from the log that the Pierburg sensor is less sensitive which is seen by smaller fluctuations.

Since the pressure doesen't decrease, the voltage shouldn't eather.

I have a feelling that placing the factory BOSCH MAF closer to the intake manifold causes it to be influenced by induction resonance and reverse flow.
Because of the smaller sensitivity of the Pierburg it's reading isn't compromised.

I have yet to confirm my theory by moving the MAF back to the factory position.

What fixes the lower rev flatspot might just causse one at higher revs...

[w202_00]

Interesting, looking forward to reading your findings.

[kowalski]

i think pierburg parts are made of better component quality than Bosch products.

my o2 sensor broke down when my car only covered 60000km's, their replacement intervall is 100.000 miles or 160000km's, my sensor didn't last that long.
Bosch had some glitches with factory tolerances a few years back, parts were inferior in build quality and broke down easily.

[Denlasoul]

Interesting, looking forward to reading your findings..
+1

[piko]

Hi!

I'm happy to report that my theory was correct.
By moving the MAF sensor back to the factory location the signal became smoother and most importantly the voltage dip at 5400-5600rpm is gone.

here's the proof:
http://shrani.si/t/1M/cp/RhJuJrb/comparisonmaflocation.jpg (http://shrani.si/?1M/cp/RhJuJrb/comparisonmaflocation.jpg)

Now that the MAF is back in the factory position I can really feel it revving to redline smoother. As for the low-mid rpm it migh react to throttle application just a tad slower but in kicks in harder when it does which makes it feel livelyer.

[Denlasoul]

That's good information for those who are considering moving their intake and/or MAF.

[piko]

Correction! Did a bit more driving today and it really seems faster to respond to throttle input... I guess the relocation was a waste of time. Back then when I read all the hype around it, I just did it. To be honest back then I didn't notice any difference, but didn't feel worse. I was running factory boost though.
The fact is the facelift engines use a totally different MAF sensor which I guess is optimally (as oppose to the preFL) placed close to the TB.

[John Jones Jr.]

Good info, thanks.