Easy way to test MAF / MAS / AMS - Page 2 - PeachParts Mercedes-Benz Forum

myarmar · #16 06-24-2007, 08:53 PM

Jim, I have it as one file, but it was too big to post here.
I think the output is very hard to interpret without knowing the exact airflow. The other known good AMM in series would be useful.
I have Snap-on scanner, and in LH system on my 600SEL reading with KOEO was 1.23V -> 20 kg/h. With engine idling about 1.6V -> 17kg/h
On M119 LH (500E) I have 1.59V -> 22.9 kg/h at idle
One of my 600SEL AMM has intermittent internal bad contact. When it failed, the reading defaults to 1.23V -> 4.3kg/h. Engine still running very good. It uses manifold pressure sensor instead. But transition from normal to emergency program is hard to miss: engine bank shuts down for a split second. That was setting DTC4 on LH module and DTC10 on DM.

JimF · #17 06-24-2007, 09:36 PM

Yes, my S500 shows 23.2 Kgm/h when it's working correctly; when contaminated, it was around 18kgm/h.

OK on the PDF, nice document to have. Tnx for sharing.

gmercoleza · #18 06-26-2007, 11:42 AM

Thanks for posting the additional info - I couldn't find it anywhere and ended up with the Pierburg info, but yes my E320 has a Bosch hot film. Like JimF, I'm not as concerned with the no-airflow reading as I am with the fact that blowing gently into my MAF returned extremely erratic results. Sometimes the voltage would actually go DOWN when I blew into it. And this was after cleaning it. Anyway, I have a new Bosch on order.

Regarding LAMBDA, does anybody know if this can be checked on the M104 without a scanner? I know on my M103 I am able to get the readings with my VOM set to duty cycle.

JimF · #19 06-26-2007, 12:56 PM

My car has the "X11" connector, maybe your car does also??

Check MENU#4 for pinouts . . .

gmercoleza · #20 07-03-2007, 02:25 PM

UPS delivered my MAF yesterday. I installed it and so far, 65 miles later, the car is running like new. I completely removed the upper and lower air intake boxes and cleaned them with a damp microfiber, then installed a new air filter to protect the new MAF. After resetting adaptations and connecting the new MAF, I measured 1.02 at the MAF with key on engine off which is right on target. I gently blew into the MAF and the voltage would rise in a linear fashion, unlike before where it was erratic and would actually drop sometimes. After starting the car, it measured 1.85 which was still high, but the reading should supposedly be 1.6 on a hot engine (mine was cold). I waited about a minute, during which I watched the voltage drop to 1.70 as the engine warmed up. I did not wait until the engine was fully hot, but I suspect it probably settled at 1.6. In any event, the behavior of this new MAF is totally different from that of the old one, and thankfully it has resolved my flat spot and backfiring. My car now accelerates very smoothly whether I accelerate gradually or quickly.

Rock Chalk · #21 07-03-2007, 02:31 PM

Congratulations! Hope it holds for a very long time...

JimF · #22 07-03-2007, 06:29 PM

Quote:

Originally Posted by gmercoleza

UPS delivered my MAF yesterday. I installed it and so far, 65 miles later, the car is running like new.

My car now accelerates very smoothly whether I accelerate gradually or quickly.

Tnx for the report . . .

If you have a high end scanner, you can read the values from the scanner while operating the car.

gmercoleza · #23 07-03-2007, 06:46 PM

I have put just under 100 miles on the car now, and everything is golden...

I still have to crank twice to start when hot, but I understand that may be a fuel pressure regulator issue and not related to the MAF - maybe I'll spend some time tomorrow looking at it.