Gutless and misfire W208 CLK

josewick

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my 230k had never pleased me performance wise since i bought it 6 weeks ago. I never thought much of it as I bought it for the missus and I thought, that might be it, heavy car, 2.3 you know.

However, last week it had developed a misfiring issue. I can be so bad that it won;t idle properly.

Having changed all the plugs, and the coil packs, it runs better , but it starts to misbehave again when it goes past 3500rpm, it will hit 4-4.5k but very reluctantly, some times the gear won;t change up and hold at 4.5k until i back off the throttle.

I have also changed the oil and fuel filter like you would do on a service.

I am starting to feel that the supercharger is not working, how do I find out?

It shouldn;t be an ignition problem now since I have changed the coil packs and plugs (it might well be it still, if someone wants to point me to the right direction)

Whatelese can it be? will it be in the limp home mode? no dash lights nor engine lights tho.

Any input is appreciated, annoying car that is, one problem after another.

Next on the list once its running properly is the rust :(
 

television

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How about the MAF, unplug it and try the car
 
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josewick

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I will try anything now.

But i have just spotted the thread on another 230k losing power, the guys says something about the flap?!?!?

Would you mind to explain to me in english :) and the possible problem..

Thanks
 
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josewick

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so, where would you think i can start with? without having to spend loads to buy new parts to try out. :(
 

television

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Pull the plug out of the MAF and try the car, ignore it if it stalls,just see if the power comes back
 
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josewick

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Television

This is a bit of a strange one, let me tell you what happened.

I just finished work and i thought i would do what you suggested, pulled the plug out. Then I discovered that the plug is already off, that makes me starting to think that the previous keeper had tempered with it.

anyway, the sympton remains the same whether or not its plugged in the MAF sensor. This is what happened.

If I take it easy and slow, i.e. around or less than 3k, it goes well and smooth. If I put the foot down and once pass around 3500rpm, it jerks, misfire and all sorts, then it will become erratic on idling, and when drive.

I turned the engine off, quickly turned it back on, all fine, same as before, once over 3.5k, it s all over the place.

Turned it off again, and tried again, all drving well, until i thought, i would give it another go, 2 roundabouts before i reached home, same, not runnnig well.

Any one any ideas?

Many thanks

Joe
 

television

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If the MAF is doing nothing then is the MAF dead, I will do some checking in the morning, though the MAF must be at fault if it does nothing, anyone ????
 

jamesmc

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As per Malcolm. MAF is the first thing to sort.

Next... check the secondary air injection valve (fitted down in-between the exhaust manifold). MB part A0021406860 It's a one way valve, is not too expensive and fairly easy to change. You'll need to pull off the air filter box, and associated pipework to gain decent access, plus you will also need a thin 27mm open ended spanner to remove/fit the valve. See item 38 in the diagram below.

B09100000003.0291.gif
 
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josewick

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Malcolm, i remember seeing apost you put up long ago but i cannot find it now, to test if the MAF is ok or dead.

Can you put the procedure up again please?

Thanks

Joe
 
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josewick

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Malcolm

Please ignore the post I commented about running it with the MAF disconnected and ti ran the same.

What a dick, that night I device that I pulled out (or i would say it was not even connected ) was the bit that connected to the air box. I do not know what it is, but its a big unit on the air box.

Anyway, checked this morning, found the MAF on the othe side of the engine. Pulled it out and ran like you suggested.

Power did not restore, in fact it ran very badly even on idling. So obviously its doing something. Once plugged back in, it idle and ran fine (up until past the 3k mark) then it will run rough and missing all over the place. I will have to turn it off and back on again to get it run normal again.
 
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josewick

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anyone else experienced the same or silimar?
 

Rinehart

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I will upfront admit that I know nothing about the sophisicated workings of MB. But by chance, the symtoms you decribe sound like a problem I had on an American V-8. (it lacked power over 3k rpm, barely ran; under 3k rpm ran fine) Lo and behold, it was a DIRTY AIR CLEANER (I don't know what you call the paper cartridge which filters the air while keeping the birds and bats out of the engine)
 

television

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Malcolm

Please ignore the post I commented about running it with the MAF disconnected and ti ran the same.

What a dick, that night I device that I pulled out (or i would say it was not even connected ) was the bit that connected to the air box. I do not know what it is, but its a big unit on the air box.

Anyway, checked this morning, found the MAF on the othe side of the engine. Pulled it out and ran like you suggested.

Power did not restore, in fact it ran very badly even on idling. So obviously its doing something. Once plugged back in, it idle and ran fine (up until past the 3k mark) then it will run rough and missing all over the place. I will have to turn it off and back on again to get it run normal again.

The MAF is one of the only things on the engine that will come back to life on a key start, I still think that is the problem
 

jamesmc

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What a dick, that night I device that I pulled out (or i would say it was not even connected ) was the bit that connected to the air box. I do not know what it is, but its a big unit on the air box.

That device is the Recirculating air flap unit. It should always be connected. When not in use it recirculates air back through the air box. At low revs, on a car that has a supercharger clutch, it also allows the engine to breath normally rather than trying to suck air through the stationary supercharger vanes.

So, with the flap unit not connected the engine will not produce any more power than a normally aspirated engine.

The flap is held open by default (with a spring) and should close under command (driven by an electric motor against the spring) from the ECU (hence the connector) when the engine load/ecu calls for it. On closure it redirects the air directly to the intake side of the engine via the MAF. My understanding is that it will open or close as directed by the ecu to maintain the required level of boost.
 
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josewick

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Right, i took it to a garage today (bosch dealer), who put it thru the scanner. Showing nothing about the MAF, but they says it shows misfiring on all 4 cylinders.. Well, i don;t need the ****** 10s of thousands of pounds worth of snap on gadgets to tell me that, even i know its mis-firing.. but it doesn;t tell me what is wrong?!?!?

They tried to do me a new set of coil packs and plugs, which were brand new since saturday.. so I took the car back..

Back to square one... Any other ideas?
 

television

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The MAF seldom shows up on STAR
 

television

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STAR is the diagnostic gear used to check fault codes and set parameters on MB cars, Bosch have their own version.
 
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josewick

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Latest updates:

All sorted now , taken to a merc specialist and they have determined that the MAF is fxxked.

All replaced, and now the car is running better than ever...In fact, the car has never run that good, so it was already faulty when i purchased the car.

So simply, i got conned by the previous keeper . :(

well, never mind, at least the car is a;ll running sweet now.
 

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