Hello-

I'm assuming this is a pretty easy replacment on a 97 C280. Is any calibration required or can I just switch them out and be done. Also, what is the easiest way to reset to CEL? Is there a fuse I can take out rather than disconnect the battery?

Thanks!!!!

You will need to reset your engine fault codes for one. Also, the engine adaptations need to be reset, and for good measure, we always reset the transmission adaptations, as I've had cars come back for eradtic shifting after the replacement of the MAF.

Disconnecting the battery on OBD-II systems does not clear the codes. Some DIY'ers have success with simply replacing the AMM and then the CE light goes out.

However, the codes are still stored in memory, and other than reading the adaptation values after replacing the AMM, you won't know if all the problems are solved. My C230 has a light hesitation under full load, and my mechanic and I are suspecting that the AMM is going south. This is the process we're going to follow...

1. Check for stored codes and read adaptation values. This will give an excellent starting point.
2. If engine adapatation values are "high" (but I have no CE light, so they have not reached the threshold) then we'll swap in a new AMM and reset the adaptation. After driving, re-read values.
3. If the AMM is not the culprit, then we'll begin with other stuff, basically fuel and spark. But, the nice thing about OBD-II is that it can give you a head start on running problems.

How do you know it's the Air Mass Meter? Is this a diagnosis, or are you shooting in the dark at solving your CE light?

PHAEDRUS242:

Why would a car suffer shift problems after an AMM replacement? Interesting.

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John Shellenberg
1998 C230 "Black Betty" 240K

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on my 1998 C230 I just switched the AMM out and disconnected the battery, I haven't detected any driveability problems since I did the work about four months ago.

I took it to the shop for another problem (differential speed sensor) and asked him to check the codes since my CEL came on before I was having the speed sensor problems. He said that he was getting a Fuel adaptation at limit message. He said it was most likely the MAF and it would cost $350 for the part and about $100 labor. Way too expensive. I can do basic car work but if there is calibration involved, I can't do that. My car has not been shifting right when I gun it so again, it makes me think it's the MAF. Thanks for your help and any more input would be appreciated.

The the person who replaced it himself and the car is running fine...were you having shifting problems? Did it smooth out?

I replaced my MAA myself

symptoms: CEL hadn't come on yet but during hard acceleration but not in kickdown phase supshifts were delayed and abrupt.

CEL light came on a few days later, disconnected battery CEL stayed off for about a week, then came back on

I checked my intake runner and found a tear so replaced intake runner, disconnected battery to clear CEL, but light came on a few days later.

Tested car and found at speed around eighty MPH cars transmission acted hesitant and shifts were trashy, thought trans was the problem

Went to this sites Shopforum and learned about codes and MAA.

Purchased a MAA from Fastlane carefully removed old unit careful not to tear or brake intake runner, just plug in new unit disconnected battery, reconnect and start up car.

Everything has worked great ever since - 4 months now - just put in a new airfilter which some say a dirty filter can harm MAA.

Good idea to check battery fluid level, vent hose, mounting, chk for any acid spill so I think disconnecting battery is the way to go

Thanks, I'll give it a try and report back. Appreciate everyone's input. This forum rocks!

John

Blackmercedes-
The transmission adaptations are partially controlled by what the engine adaptations are reading. They work together hand in hand, and as the engine adaptations are changing because of faulty AMM readings, the trans adaptations will change to a point as well to compensate for what it believes is going on with the vehicle. When the engine adaptations go back to default and the trans adaptations do not, they may be in a place where they don't agree with one another, so to speak. This can cause shifting behavior that is not what the customer is used to feeling when they drive their car.

I see! Thanks! Whatever happened to "simple?" We had better get used to cars operating like computers. Re-boot, crash, error, etc.

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John Shellenberg
1998 C230 "Black Betty" 240K

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Hello PHAEDRUS242-

How do you reset the adaptations? Is this somthing a DIY'er can do or do you need a computer. Just trying to avoid the shop. Thanks!

You need the SDS. Star Diagnostic System.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

Blackmercedes is correct. You'll need some pretty serious hardware to get the job done right. Once you've replaced the part, I would hit up your local dealer, bring some donuts or some similar goodies for the service advisor and techs and see if you can have them just reset the engine and trans adaptations and let you drive it from their, no warranty expressed or implied. You may be able to get away with .5-1 hr labor, or if you have a good relationship with your advisor, they may do it for free.

So if you just continue to drive, it won't eventually adapt? I'm referring to either/or/both the trans and engine meters.

Also, please see my post on c280 torque converter. It's relatively recent. I'm wondering if those sympoms have something to do with this. Thanks

Yes, it will readapt, assuming this actually is the problem. I don't doubt that it is, but I'm not saying it "has" to be the problem, but the mixture adaptation certainly will come back into line by itself, there is no real reason it has to be reset after replacing this part.

You may find it neccesary to use different throttle inputs when the MAF sensor is replaced vs with the old one because the mixture is being affected. The throttle position values will affect transmission adaptation (short term), so possibly this is why the transmission may be felt to shift differently. This is the only reason I can think of for the replacement of the MAF sensor to affect shift quality. Otherwise the MAF sensor has no direct bearing on shift quality.

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As I see it, resetting the adaptations is a smart move in case the problem is not solved. It'll give you a good picture of what is happening from a certain point.

But, if you don't have access to SDS, or want to pay for it, then you can simply replace the parts and drive.

__________________
John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif