C240 W202 Engine Judder

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arorat

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My C240 started juddering last year, the Indi diagnosed the problem to HT leads and spark plugs, everything was fine after that and a service.

Although the car is fine under normal driving, if I accelerate hard (hit the nodule under the accelerator) the car starts juddering and has to be turned off and then restarted to get rid of the engine judder. Today with the hot weather the engine judder came back after re-starting after a local trip.

The car has done 118,000 miles.
 

andy_merc

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Hi there I have had a similar problem on my wifes 240 sport and it was eventually tracked down to the Mass Flow Air sensor, these thinks are quite sensitive, it may just need cleaning but you may need a replacement. Cheers Andy
 

Hertfordshire Merx

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Ideally the car needs to be put on Star Diagnosis and have a quick test carried out on it. It could be caused by a faulty air mass sensor but there are other things that can cause the same problems. Does the engine have any starting issues?
 
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arorat

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Thanks Andy.

Hert Merx... The car starts fine, where would the MAF (its called MAF right ?) be located on a C240 Sport, 1998.

Comment noted re: Star Diagnostics.
 

nickcc101

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The MAF is located in the air intake hose. Previous advice from well known member has been to remove the electrical connector off the MAF and see if the fault goes. If it does then the MAF will most likely be the problem.
 
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arorat

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Thanks, i have taken the MAF off, can i use pressurized air the ones used for cleaning computer equipment to clean the MAF sensor ?

some one mentioned Parrot of Doom had listed a procedure on how to clean. i did a search but could not see that post under Parrot !!

btw: I probably answered my own question on how to clean, see this link
 

stevesey

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The MAF is located in the air intake hose. Previous advice from well known member has been to remove the electrical connector off the MAF and see if the fault goes. If it does then the MAF will most likely be the problem.
x2

Symptoms on mine were pretty much identical - fault not really noticeable under normal driving (car just felt slightly "off") - floor the throttle and it didn't like it at all. Try it with the MAF in place but electrically disconnected, if things are smoother change the MAF (£100 from eurocarparts for a Bosch one - ask for best price/discount).
 
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arorat

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Steve

After cleaning MAF same problem, also tried driving with electrical connector disconnected again same problem - foot down a little and car hesitates, no joy with foot fully down.

With these posts i am performing self diagnostics, what i am concluding is if the the car runs better with electrical connection disconnected then its the MAF otherwise put on Star Diagnostics as MERX said.

Would you agree ?

Any Indi MB Engineers in Surbiton KT6 areas or in KT areas ?
 

roofless

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The MAF is located in the air intake hose. Previous advice from well known member has been to remove the electrical connector off the MAF and see if the fault goes. If it does then the MAF will most likely be the problem.
GUILTY i had second thoughts on this one it was a bit early to be thinking :Oops: but no harm in cleaning it as per P OF DOOM

http://forums.mercedesclub.org.uk/showthread.php?t=18298 the maf or air mass sensor on your car can be found hear 119 in the 2nd diagram http://www.detali.ru/cat/oem_mb2.as...GM=717.464&CT=M&cat=19X&SID=14&SGR=030&SGN=01 you can buy the servisol spray from maplin http://www.maplin.co.uk/Module.aspx?ModuleNo=28994
 
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arorat

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HertsMerx shame you are not in Kingston/Surbiton, it seems i need the star diagnostics.
 
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arorat

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Engine Judder Fixed

The constant engine judder has been fixed, here is a breakdown of the recent visit to TM Motors an Indi Mechanic;

2 days back, I had the car on Star Diagnostics and the guy tells me the two front O2 (Lambda) sensors were showing 0 (zero) when they readings should have been fluctuating, cylinder 2 was misfiring. Before I went to Brooklands Merc to get the O2 Sensors, cyl 2 coil was checked by replacing with another working unit – same problem. Brooklands Price was £136 + Vat for each O2 Sensor, I called Europarts, 2 x Bosch O2s for £117, I placed an order however when I went the next day they apologised as there was zero stock in UK, hmmm... Called GSF they managed to get me two at £147, unfortunately one was Bosh and the other NTK.

TM Motors fitted the O2 sensors, but the Start Diagnostics still showed Zero, at that point I walked away from the car giving the engineer a breather to do further analysis, the Venturi was cleaned still the same problem, then lastly the MAF was replaced as a whole unit and the engine came alive. I understand the faults were cleared and something rebooted.

The car is a totally different drive and I don’t feel threatened by traffic behind me, i.e. the car can accelerate like the day it came out of the showroom.

Here is the breakdown

Initial diagnostics £50
2 x O2 from GSF £128.05 + vat
1 x MAF unit from TM Motors £218.02 + vat
1 hrs labour to fit O2s £50
Further diagnostics and replace MAF £50 + Vat

So in total £555.48 to fix the problem.

The old O2 sensors had white coating on the sensors, the mechanic told me it may have been due to Tesco Petrol Silicon incident.

I guess £555.48 does not justify fixing the fault and would have been more expensive had TM Motors supplied the O2 Sensors (at least £136 + vat each what Merc charge), by changing the O2s the Catalyst has probably been saved and the MAF was required although more expensive than what Merc dealerships sell them at.

So all of you guys who said replace the MAF were spot on.

Can some one console me that the cost was justified or tell me otherwise so I could have spent less :confused:
 

Hertfordshire Merx

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The silicone in fuel incident by some of the supermarkets was some time ago now, possibly almost a year ago and I think is questionable. It is normal to have a white/beige coating on the O2 sensors. Seriously as long as you're happy with what you paid, and it sounds like the car is running very well now, then thats the main thing.
 

jberks

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To be honest, probably a MAF replacement would have done it. My E240 was hesitant. Diagnosed as an O2 sensor. It went into safe mode a few days later by which time the O2 sensor was in, so they replaced it,only to find that the problem persisted and reuired a new MAF. I wonder whether a dicky MAF can show up as O2?
Anyway now its all been done, at least you can be sure your engine management system is 100%.
New plugs and leads are also worthwhile. I tended to find that idle deteriorated once the leads were > 3 years old. Plugs last 60-80k / 4 years so depending on how old they were ...
 
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arorat

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The silicone in fuel incident by some of the supermarkets was some time ago now, possibly almost a year ago and I think is questionable. It is normal to have a white/beige coating on the O2 sensors. Seriously as long as you're happy with what you paid, and it sounds like the car is running very well now, then thats the main thing.

HM Thanks, I am happy the car is back to normal, but it concerns me that these cars can cost so much to fix when something goes wrong. Was £555 justified, would another mechanic have taken a different approach ?
 

Hertfordshire Merx

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Without seeing the car and diagnosing it properly its difficult to say. O2 sensors do fail but not very often and are easily tested.

If the fault self-adaptation appears in the engine control unit fault code list then you can be pretty rest assured that the air mass sensor is at fault.
 
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arorat

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You know your stuff very well as this reply proves. I was not given the option to check the O2s, I was told the white coating was silicone, and no mention on self-adaptation codes.

In retrospect I should have thought about this... if the engine on start-up started juddering, then it would not be the O2 as surely they can not heat up that quickly and respond back to the ECU for it to misfire, so it would have to be the Sparkplugs, leads, coil or MAF as first 3 were already checked then the attack should have been on the MAF.

Sorry for digging this topic further, I used to be a Cisco engineer and have strange need to understand everything :Oops:
 

Hertfordshire Merx

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One question arises out of your last post, why did they feel the need to remove the sensors if they had checked them properly? Maybe they weren't working... O2 sensors should be tested after a good run as you say to be hot enough.

Again no problem, if I can be of any assistance to you in the future no matter how trivial just drop me a line I'll do what I can to help. Its all about the passion for the brand...
 
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dbanbery

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tbh the first port of call for most competant mechanics would have been the AFM. especially if the sensors cost nearly as much as the replacement. looking at what problems people have [me being on of those] the single most common fault is the AFM.

as Hertfordshire Merx said, the sensors rarely go wrong. the AFM or MAF or whatever is a common fault of mercs that are a good few years old, and it would always be the first thing i would look at if i was getting running issues. to be honest there seems to be a lot of mysticism around this part of automotive electronics, when it is 70% of the time the same thing.

i'm not a specialist, just someone who has had similar problems and has read a lot of posts from others on similar issues, indeed posting about the same problem with my car. this was solved with a spare my dad had in the garage he bought in error a few years back, and it solved the problem pretty much. however, it was a cheaper one and after a bit i've had a few more issues, but it works better than disconnecting it and its still driveable so i'm going to replace it when i can be bothered.
 


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