ML270 reacuuring MAF Sensor problem

[m11nch]

Hi I hope someone can help me get to the bottom of my problem i have a 2000 w163 that ever since i bought it has gone into limp mode i sent it down to an indy said if was a faulty maf &replaced the maf sensor & after that it was ok for around 3 months. it went back into limp mode so i did the inlet manifold & M55 mod plus an egr delete along with a new maf,
now every so often it still goes into limp mode especially when cold or on kick down,
so i decided to buy a star c3
and after a new maf sensor today im getting the code P0100-01 mass flow air voltage to low
so i checked to voltage like the star says and its all ok
now im stuck what to check
any ideas please
thanks

 

[mersum1es]

You may have boost leak somewhere, or EGR is not shut properly. Or the blocked cat etc. again one thing hard to hunt down, strong cross effects...

 

[m11nch]

Thanks for your quick reply, would a leak on the turbo boost side cause a maf dtc ?

I did remove the precat but i haven't got a welder to finish the second one,
what would be the best way to pressure test the system.
Also which way would the egr be if fully shut towards the vacuum diafram or away ?
sorry for asking to much but i am stubborn & want to learn

 

[m11nch]

I'm not sure if this help diagnosis but the once I clear the fault code & turn off ignition
I rescan the car "not running" and the DTC comes straight back

 

[mersum1es]

I'm not sure if this help diagnosis but the once I clear the fault code & turn off ignition
I rescan the car "not running" and the DTC comes straight back

So it's nothing to do with air mass or pressures (btw check that all your pressure sensors are giving same reading now when not running)

Did you bought original MAF? Chinese cheapos are usually crap, use only Bosch or Pierburg make....

 

[m11nch]

It's was a pierburg which I was told is oem
what pressure sensors/tests should I check
Thanks

 

[mersum1es]

It's was a pierburg which I was told is oem
what pressure sensors/tests should I check
Thanks

Basically all pressure sensors (boost, exhaust) should give ATM pressure at the beginning. Try to remove EGR shunt too, if there is something wrong now...