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Discussion Starter #1
Hi, I've just got my first Mercedes and so I wasn't sure what to look out for when I got it. My previous car was a Mazda 121, so the sheer size difference took some getting used to alone. After a few weeks I've identified two, or maybe 3 problems and I'd love some advice.

1. Engine sometimes hesitates when accelerating. It also feels like it's lacking in power going up hills. I'm assuming this is an MAF sensor problem. I read that disconnecting it and driving would let me ascertain that for sure (will drive properly with it disconnected if it's got problems). The question: Is it ok to just disconnect the wire with the key out of the ignition, drive it and then reconnect it with the key out of the ignition again. There are no warning lights at present and it's not a particularly bad problem, but I'd like to get to the bottom of it before it gets bad.

2. Slightly noisy fan belt. It's a squeaky sound as though It needs oiling. I think this may be connected with a loud squeaking/squealing noise when I have the steering wheel fully locked (particularly in reverse). Maybe not. I'd appreciate any insight into this.

Thanks in advance.

P.s. I really wanted a Subaru, but now I don't think I'll be able to drive anything else. Just have to get used to other road users thinking I'm a ***** now! <grin>
 

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Discussion Starter #3
thanks anonymous. I'm in a manual, so it shouldn't be gears that are the problem up hills. We also only have one type of fuel available in Ireland, so I don't know that I can do anything about that, and shouldn't have to!
 

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The noise you hear when having the steering wheel fully turned is the power steering pump. And its never a good idea to have it fully turned for an extended amount of time, or to turn the wheel when the car is stationary.

The noise may be caused by a dying pump or low fluid. I know in my 91 TC low steering fluid was the cause of that sound. It will still make a sound even if its working fine, but will get louder when something is wrong with it.
 

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Discussion Starter #5
Am I right in thinking that the PS is in some way connected to one of the wheels the belt goes around at the front of the engine? I'll check the fluid levels in the morning. Cheers.
 

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Ok, so I disconnected the MAF sensor today (just unplugged the electrics). The difference? Not a lot. If anything it was slightly worse when disconnected. The hesitation only seems to take place at lower revs (below 3k) This explains why I notice a lack of power more in higher gears (where it takes ages to accelerate from say 80kmph to 120kmph). If I'm in 5th gear flooring the accelerator is much the same as just gently pressing it. The hesitation happens most in first and second gear where I would generally be accelerating more rapidly (to join traffic on motorway etc). The hesitation feels like you touched your foot off the brake. It lasts between a half second and two seconds. Then normal service is resumed. It is not the brakes.

Looking at the Haynes manual, they say it could be spark plugs (would this not be more consistent?), air leak at the throttle body, inlet manifold etc (It all looks good (no signs of rubber or plastic corrosion to my eye), Fuel injection blockage (no idea how likely this is or how to go about diagnosing this further). No mention of MAF sensor at all.
 

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Ok, so I disconnected the MAF sensor today (just unplugged the electrics). The difference? Not a lot. If anything it was slightly worse when disconnected. The hesitation only seems to take place at lower revs (below 3k) This explains why I notice a lack of power more in higher gears (where it takes ages to accelerate from say 80kmph to 120kmph). If I'm in 5th gear flooring the accelerator is much the same as just gently pressing it. The hesitation happens most in first and second gear where I would generally be accelerating more rapidly (to join traffic on motorway etc). The hesitation feels like you touched your foot off the brake. It lasts between a half second and two seconds. Then normal service is resumed. It is not the brakes.

Looking at the Haynes manual, they say it could be spark plugs (would this not be more consistent?), air leak at the throttle body, inlet manifold etc (It all looks good (no signs of rubber or plastic corrosion to my eye), Fuel injection blockage (no idea how likely this is or how to go about diagnosing this further). No mention of MAF sensor at all.
Haynes? I dont think Haynes makes a manual for this car, and if so I wouldnt trust it. Bentley makes the manual for this car.

Also, I dont think your supposed to run the car with the MAF disconnected...

You could have a vaccum leak somewhere, thats possible. That will effect your idle but not be noticable at higher rpms.
 

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Discussion Starter #8
Vacuum leak got me thinking. It has a generic fuel cap on it. Just pushes into place. Would this be a possible cause of my hesitation? It does feel like there is a lack of fuel going. Is there some sort of vacuum measurement taken at the fuel tank?
 
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