seenastyle

Hi all,

I think my MAF is giving me issues, but I want to test it at home before I spend $250-$350 on a new one just to find out that it wasn't the source of the problems. I watched a few videos on youtube about how to test it, but it comes down to whether our cars' MAFs output a voltage level or a frequency signal. If the latter, then I would need an oscilloscope as opposed to a simple multi-meter.

Does anyone know? And if so, do you know the idling value and the general range when otherwise more air is flowing through?

Thanks!

AMG_only

Whats it doing?

seenastyle

Car stutters in idle and seems to have less power. Computer gives OBDII trouble code P0171 "System Too Lean (Bank 1)," which is consistent with my symptoms. This is often caused by issues with the MAF. I removed the MAF and cleaned it with CRC MAF Cleaner as members on this forum and elsewhere have recommended, but I still have the same issues, so it's possible that the sensor is simply faulty, not dirty. I'm trying to determine if it's in fact broken, or the problem is being caused by something else like a vacuum leak.

A bit of extra info regarding the interface: From what I can tell, it has 4 pins (actually it has 5 but only 4 conductors, one of the slots is empty):
pin 1: ground
pin 2: 12V power
pin 3: MAF signal output
pin 4: ground

Glyn M Ruck

Almost certainly the MAF. Our MAFs are hot wire and output varies with cooling effect of air volume through the MAF. I do not know the voltage range. You can try cleaning it with CRC MAF cleaner. If you buy a new MAF make sure it's the genuine Benz article. P/N is on the black plastic cover. Be careful buying MAF's on the internet unless from a proper Benz supplier like RMeuropean. VW/Audi MAF's look identical & fit but will not work on our cars.

ohlord

have one bank,thus the one code.Sys rich/lean is not setting itself because the mass air is out of range.Did you take it apart to clean it?If so and your check engine light is on or pending replace the maf $279 delivered www.autohausaz.com
Make sure you seat it properly on install.
Other items that can throw TL are a dirty fuel filter dirty air filter
Voltage rises on air flow from about 1.25 volts up to almost 5V.

Glyn M Ruck

Thanks for that I was not sure of the range

seenastyle

Yes, removed the air filter housing to get to it and sprayed it down by itself.

So 1.25-5V is in the range I've heard of when people talk about MAFs in general, are you saying that specifically our Mercedes C230 MAF is in that range for sure? Or are you saying in general for MAFs?

GlynMRuck and ohlord, thanks for the tips