Is it the MAF??? Help needed please!

[eurico]

Hello

My '02 C270 autobox was playing a bit. Kickdown was harsh and sometimes lost drive. Gearchanges where erratic and rarely smooth. I tought it was due to the oil never being changed. When done, things got better but never enough. Then I suspected the MAF sensor. Cleaned it and it ran fine. Then things got back to bad. Cleaned it again and the same happend: improved but the performance degraded with time. Then I thought it was time to invest in a new MB sensor and, why not, a new oil separator - the black plastic thinghy for the crankcase vent. What a diference! New car. Gearchanges where smooth and instant. Kickdown was smooth. I never had the car like this...till next day. Everything went back to "normal".
Can anybody give a hint of what's happening. Can a sensor last one day? Can it be the sensor circuit that's damaging it with too much voltage or something of the sort? Any ideas? Help please...I am getting desperate

Thanks for the patience to read this long post.

 

[television]

Where did you guy the MAF, why not unplug it and try the car.

 

[eurico]

Thanks Malcolm
I bought it from a dealer. Same part number as the one before it. Brand was different. Original was Pierburg. New one is T2S.
I tried unplugging the thing and I lost kickdown and revs wouldn't go past 3000. What should I look for when I disconnect the bugger?

 

[television]

Thanks Malcolm
I bought it from a dealer. Same part number as the one before it. Brand was different. Original was Pierburg. New one is T2S.
I tried unplugging the thing and I lost kickdown and revs wouldn't go past 3000. What should I look for when I disconnect the bugger?

When it is the MAF faulty the car will normally respond much better unplugged, but this appears to not be the case on your car, the only snag is there is not much else that can do this.

I do not know what the maker od the T2S sensor is, the work must be guaranteed can you go back

 

[eurico]

Malcolm

Yes I can go back with it. Trouble is the dealer doesn't believe the MAF has anything to do with the gearbox acting. Am I into something worse? I cannot believe that's the case because if it were mechanical, it wouldn't get better with the sensor clean up or replacement. Mind you, when I replaced the sensor, it was a totaly different car that I never had driven before!

 

[television]

Malcolm

Yes I can go back with it. Trouble is the dealer doesn't believe the MAF has anything to do with the gearbox acting. Am I into something worse? I cannot believe that's the case because if it were mechanical, it wouldn't get better with the sensor clean up or replacement. Mind you, when I replaced the sensor, it was a totaly different car that I never had driven before!

The gearbox does rely on having a certain power from the engine, when the engine is down on power, the gearbox does not know what to do so it clamps up and goes into the limp home mode.

I think it is a cheap filter that you have, and of late the have been many of these around with some folk trying to earn a few more bucks, in almost every case the correct MAF has fixed it

 

[barrieeld]

interesting topic, and i to am having the same issues with my s320 cdi.

Does your car run really sluggish when cold also? Almost like the gearbox will want to rev high rather than change?

I had a new MAF fitted to the car but the mechanic said it made no difference (even though he diagnosed this as the issue) could this be a rubbish (read low quality) part as mentioned in this thread?

 

[television]

This business of fakes could be a big issue, we had a big issue two years back in the semiconductor field when we were flooded out with power transistors that were in the correct cases, you could measure them out cold, and the read out perfectly, but fitting them they just blew up. These were all marked correctly and impossible to tell from the real thing. My suppliers had to cut open a sample from every new batch to check if it was the real thing and these things only retailed for £2.50. Just think of what could be earnt on MAF's

 

[satbasi]

Hi everybody, I seem to have a similar problem with my C180, its a 97r (facelift), auto 5sp, when cold the engine wont start unless you keep your foot on the gas @ approx 2000 rpm for 3-4 minutes (until engine is warm), before this time and the car will cut off again. Once warm it will drive ok but the acceleration is terrible. When warm, if swithed off and then restarting, I have to just touch the accelerator just to give it that 'encouragement' to start. It will not rev past approx 3000rpm. However, when I unclip the MAF - starting is fine from cold and it runs very well ( I dont know how it should run usually as the problem has been there since i bought the car in Aug 2007 and its my first c180 - had a 190e years ago which was fine) So, does this say it is the MAF? Merc specialist claims it is and quoted 180 pounds for a replacement and said you must get it done rather than do it yourself as ''youve gotta reset the sensors, init mate''. Is this so? Can the sensors not be reset by disconnecting>reconnecting the battery? By the way tried Halford contact cleaner - no luck. Then Maplin Switch Cleaner - slightly better running but problems vastly exist.

 

[Dieselman]

Satbasi and eurico.

I suspect both of your problems are MAF related. Just fit new ones, there is no reset to do.

 

[MFK]

I am not an expert but could this problem be related to a faulty Throttle position sensor or throttle body problem.

MFK

 

[eurico]

Malcolm and Dieselman
Thank you very much for your help

I am wrecking my brains with this!!!

1st sensor was genuine MB bought from a certified MB dealer (at least there was a big star at the entrance). This lasted for 20 miles. Symptoms where, as before:
- harsh and erratic gearchanges - like there is difficulty in the clutch enganging or takes a bit too long and the engine revs a little
- kickdown is a little too literal for my likes - comes with a real kick
- when coasting down a lane, box holds on to 2nd or 3rd gear too long and then snaps into the next ratio and the car jumps forward.
- manual operation (tipping the lever) is not imediate. The box does what it want's to even if the engine can handle the next gear perfectly.
- change between coasting and light load - lifting your foot and pressing slowly again - is very jerky. Like a carburettor car with rich setting. Sometimes it's so bad that it's like having a big gap in the diff.
- can feel first gear being engaged when coming to a stop.
- once when cold, gearbox went to safety mode and stuck to 3rd.
- car is very unpleasant to drive
Went back and they hooked it to the star thingy. Faults where found for the gearbox safety mode and not much else. Oil level was checked and it was a bit low - minus 0,5 liter. OK, I thought, this was the real problem.
Dealer offered me a new maf sensor, fitted it and filled the gearbox to correct level at 80ºC. Tested the car and it was a real joy to drive...till I got back home - 30 miles later. Everything came back to "normal". AARRGGHHHH! Please help...Please ask questions...Please give me an idea of what's going on...Please...

 

[Dieselman]

It could be the electronic plate in the gearbox not properly sensing the speeds.
I know of an E220 CDi that would hold 3rd for no apparent reason when cruising.
It had new electronic plate, ECU, gearbox and torque converter. MB UK were involved but to no avail. The car was sold.

 

[eurico]

Wouldn't that come up with an error code on star?

 

[Dieselman]

Depends on whether it has another reference to compare to, if not how does it know it's out of range?

 

[television]

What are the first 6 vin numbers 203 and the next 3 please

 

[BlackC55]

It is pointless just bolting on parts until it fixes it. Proper dagnosis is what is needed.

 

[eurico]

Malcolm, I have PM the whole vin

 

[eurico]

Depends on whether it has another reference to compare to, if not how does it know it's out of range?

Doesn't it have an output shaft sensor? Or is it the same as you mentioned?
Anyway, what are the other syptmos for sensor plate malfunction?
Would it get any better with MAF cleaning or replacement? That's what puzzles me. Whenever I touch the MAF, the car goes better.

 

[eurico]

It is pointless just bolting on parts until it fixes it. Proper dagnosis is what is needed.

Any ideas? Help would be much appreciated.