An Unusual Fault

[johnclowes]

I have a 2001 E 240 estate which works perfectly most of the time. Occasionaly the yellow engine management light comes on and the tickover becomes rough and the car may lack power. The car never stalls and if I stop, switch off and restart the problem goes away although the yellow light stays on for about three further starts. There seems no pattern to when the problem occurs - sometimes when overtaking at highish revs, other times at low speeds.

The diagnostic system shows there was a fault but not what caused it. (It seems from reading posts that I must leave the engine running for the diagnostics to pick up the fault but I am not always within reach of a dealer!) I am about to let Mercedes investigate the problem but would like to give them as much help as possible to keep the bills down for the investigation.

Has anyone any bright ideas what is causing the problem?

 

[LNM]

You are suggesting that Mercedes dealers will actually listen to you ?

Wow, where abouts is your nearest dealer ?

 

[piestore]

Hi John

What you describe sounds like a misfire the engine managment system detects a missfire and shuts of the injectors to the relevant cylinders, when you recycle the ignition you cancel these faults and this becomes a stored fault. after 3 consequetive ignition starts with no faults the engine malfunction indicator light (MIL) goes out until the next detected missfire. the most common cause on your engine are MAF sensor (mas air flow) and contaminated fuel. My best guess is air mass sensor

As for LNM are suggesting that anybody would not listen to somthing that might help them sort out a complicated problem dealer or not, or is that just a big chip on your shoulder. If you have had a bad experience share it with us all.

PS try to be more constructive LNM

 

[sclass]

Hi John

What you describe sounds like a misfire the engine managment system detects a missfire and shuts of the injectors to the relevant cylinders, when you recycle the ignition you cancel these faults and this becomes a stored fault. after 3 consequetive ignition starts with no faults the engine malfunction indicator light (MIL) goes out until the next detected missfire. the most common cause on your engine are MAF sensor (mas air flow) and contaminated fuel. My best guess is air mass sensor

As for LNM are suggesting that anybody would not listen to somthing that might help them sort out a complicated problem dealer or not, or is that just a big chip on your shoulder. If you have had a bad experience share it with us all.

PS try to be more constructive LNM

Now Now children dont be nasty to each other If anybody has a chip on their shoulder its you. :roll:

 

[johnclowes]

Thank you Piestore.

The car is due in next week so that information should be very helpful - the dealership in Stoke, Draytons, seem to be the exception to LNM's experience - I hope they don't disappoint!

I will report back.

 

[Richard Murray]

Mass Airflow Meter is a good call. Had the same problem on my Audi TDi Avant. Power completely died. At first I thought it was the turbo, or a collapsed fuel pump.

Although it showed up on the diagnostics - it didn't point to exactly where. One refurbished MAF later and I'm back in business!

Richard

 

[OlafMaxwell]

I have to agree with LNM and that is speaking from experience. I do not have a chip at all, have long given up on MB service here.

Sorry if it disappoints, and sorry if complaining about bad service disappoints.

Personally I think bad service is unacceptable and see no reason not to publicise it or warn people, they should be aware that when they buy Mercedes they get a great combination- the best cars in the world and the worst distributor/dealer support. When the reviewer of the E220CDI in a main Sunday paper last weekend says 'Mercedes have their quality issues of late' you need to know what support you will be getting. Equally I see no reason not to publicise the good dealers, the ones who value your business.

 

[jberks]

Hi,
My 2000 E240 had been a bit hesitant on pick up but only very slightly - 1/2 a second or so one out of 10 times. On the way down the M62 a couple of days ago, I pressed the throttle to pick up from 80, (unless your the law in which case it was 50) it hesitated and then slowed down !
It limped to the workshop (30 mph flat out and 0-30 in 40 seconds - sorry if you were stuck behind me !), juddering at idle when in gear. One new oxygen sensor and good as new - or so they tell me, picking it up later. I had a similar problem on a Granada a few years ago and that was a knock sensor. Is it me or do modern cars have less reliability the more complex they get !
By the way, I've started to use a specialist. In my view and experience, dealers are only any "good" if the car is under 3 years and within warranty - they don't see that many older ones so haven't got a clue when things get odd. 3 visits with dodgy supressor caps and a misfire and was told it was 'normal' for a 30k mile v6 to shake at idle!

 

[jberks]

Add an air mass sensor. Car runs great, shame the same can't be said for my wallet.

 

[Warren Stevenson]

Hi there,
Simple things like old sp[ark plugs or a coil (HT) misfire can cause the rough running and "flag up" the engine light as the oxygen sensor picks up excessive hydrocarbons in the exhaust caused by the fuel not burning properly.
Repalced plugs if they haven't been done for a while and check ignition system for signs of"cross-firing" or shorting out.

Good luck,
Warren