Shifting problem. is it Auto transmission or air mass air malfunction?? - PeachParts Mercedes-Benz Forum

hussain2002cab · #1 08-31-2007, 11:37 AM

{mercededes benz, 1998, E320, gasoline engine 112, auto trans 722.6}

My transmission starts to act strangely, auto trans works fine in W mode but in S mode gear stuck some times in 3rd & 4th shift, and even the shift return is hard. Then I have recognised that if I want it to shift in S mode I have to stop first then press the acceleration pedal very softly . I'm wondering if its air mass flow malfunction or its hydraulic or mechanical problem[/FONT]

I have already replaced filter and atf oil (titan 3353)

lkchris · #2 08-31-2007, 11:43 AM

Hard to imagine any relationship between MAF sensor and auto trans performance.

gmercoleza · #3 08-31-2007, 11:58 AM

Quote:

Originally Posted by lkchris

Hard to imagine any relationship between MAF sensor and auto trans performance.

Quite the contrary - my 1997 E320 W210 tranny was flaring VERY badly between 2 and 3 until I replaced the AMM/MAF. I had a similar symptom of bad AMM/MAF - I had to accelerate very slowly at low RPM or the car would hesitate and backfire. After I replaced the AMM/MAF I noticed the trans problem was completely gone. I was almost certain it needed at least a tranny service, but I was wrong - it was the AMM/MAF. Somehow, there is a connection, and the computerized 722.6 tranny does appear to use input from the AMM/MAF.

hussain2002cab · #4 09-12-2007, 04:27 AM

you are right, it was air mass flow issue

many thanks

gmercoleza · #5 09-12-2007, 09:10 AM

I believe it is actually called an Air Mass Meter. Glad to hear you fixed it!

ILUVMILS · #6 09-12-2007, 12:35 PM

Quote:

Originally Posted by gmercoleza

....and the computerized 722.6 tranny does appear to use input from the AMM/MAF.

MAF sensor data is used by the transmission, but in a round-about way.

The MAF sensor data is used by engine management (ME-SFI) for a number of things. One of these things, when used in conjunction with throttle position, manifold pressure, etc., is load calculation. This information is shared with the transmission control module (ETC.6) via "CAN C" and has a considerable influence on shift quality.

syljua · #7 09-13-2007, 07:38 AM

Quote:

Originally Posted by ILUVMILS

MAF sensor data is used by the transmission, but in a round-about way.

The MAF sensor data is used by engine management (ME-SFI) for a number of things. One of these things, when used in conjunction with throttle position, manifold pressure, etc., is load calculation. This information is shared with the transmission control module (ETC.6) via "CAN C" and has a considerable influence on shift quality.

Correct, even more about the 722.6 is here;

http://w210.pietrzyk.net/transmission7226.htm

Especially this table, shows what is important for
the 722.6 to "know", and there you see "Engine Load";