My dealer had on his forecourt a Jan 2000 c240, so I took it out for a spin for interest, just to see how it compared to mine.
I found it was completely different. The throttle response was way better at low revs, but poor higher up, and the gearchanges were very different. Mine are very smooth, almost too slippy at very light throttle. I also have an issue with the 3rd to 4th change, which can be a bit quirky sometimes. Overall, I noticed that the car felt very different to mine in its driving characterstics. I drove it for long enough to be sure that the adaptive gearchange was used to me.
Then I had a thought. I swapped out the MAS into mine, and took it out. Amazing - my car was now the dealer's car!! Drove the dealer's car with my MAS, and hey presto, it was mine.
With my eyes closed (figuratively speaking) the entire character of the car is contained in the MAS sensor.
I talked it over with the workshop manager and he was not surprised. With this knowledge I have ordered a replacement MAS as we are pretty sure it will iron out my 3rd gear quirks (the shift to 4th flutters at certain throttle openings). This will be fixed instantly, and he says that if I pop inot the workshop he will reset the engine adaptions as well and I should get some more power and smoothness overall.
I asked a him more more about this. It seems the g'box adaption is temporary memory of the last several changes, and can be reset by a battery disconnection. The engine management is different - the system learns the relationships beween the sensors, and these do not get overwritten with a power loss- so my ECU is using a table that was learned up to 80,000 miles ago. What he expects to happen is to reset the ECU, then it will learn the relationships between the new MAS and the other sensors, notably the crank sensor, cam sensors etc and this will take into account 80,000 miles of bedding in.
Anyway, I pick up the MAS at lunchtime, I'll bang it in straight away and see what happens. It will go into the workshop later this month for some other work and I'll get it reset then, and we'll see if that makes any difference.
I found it was completely different. The throttle response was way better at low revs, but poor higher up, and the gearchanges were very different. Mine are very smooth, almost too slippy at very light throttle. I also have an issue with the 3rd to 4th change, which can be a bit quirky sometimes. Overall, I noticed that the car felt very different to mine in its driving characterstics. I drove it for long enough to be sure that the adaptive gearchange was used to me.
Then I had a thought. I swapped out the MAS into mine, and took it out. Amazing - my car was now the dealer's car!! Drove the dealer's car with my MAS, and hey presto, it was mine.
With my eyes closed (figuratively speaking) the entire character of the car is contained in the MAS sensor.
I talked it over with the workshop manager and he was not surprised. With this knowledge I have ordered a replacement MAS as we are pretty sure it will iron out my 3rd gear quirks (the shift to 4th flutters at certain throttle openings). This will be fixed instantly, and he says that if I pop inot the workshop he will reset the engine adaptions as well and I should get some more power and smoothness overall.
I asked a him more more about this. It seems the g'box adaption is temporary memory of the last several changes, and can be reset by a battery disconnection. The engine management is different - the system learns the relationships beween the sensors, and these do not get overwritten with a power loss- so my ECU is using a table that was learned up to 80,000 miles ago. What he expects to happen is to reset the ECU, then it will learn the relationships between the new MAS and the other sensors, notably the crank sensor, cam sensors etc and this will take into account 80,000 miles of bedding in.
Anyway, I pick up the MAS at lunchtime, I'll bang it in straight away and see what happens. It will go into the workshop later this month for some other work and I'll get it reset then, and we'll see if that makes any difference.
If you have time I'd be interested in a detailed explanation - maybe PM?
