E240 2001-idling probs/misfire

[sunil]

Hi, just joined this club,hope someone can advice please ............

have a E240 year 2001, done 45,000 miles, just yesterday while driving car started eratic idling at the traffic lights, lights turned green, pressed pedal but NO power, there was a total loss of power, car did move but so slooow hardly picked up speed as it should do , got home at last parked up car, looked under bonnent ....... could'nt see anything unusual but engine was very shakey

1. any one any ideas whats possibly wrong
2. will the fault show up on a merc service computer?

await your replies

regards .......... Sunil

 

[mercdriver]

is your engine management light on? or did it come on at all?

Mark

 

[sunil]

Hi mark, no lights came on at all, the dash was clear of any warning lights, i just tried the car this morning, started up fine, however once it hit operatiing temp you can feel the car missing,not as bad as last night, but its def missing a beat..........not driven it onto road incase it conks out ...... thinking of driving to a garage after the morning rush ......... but Im worried if the fault will show up on a merc computer, rather then changing parts and hoping to resolve, do you or anyone know if such a fault will show up on the computer diagnostics??

 

[robbo]

could be your MAS sensor.

 

[G MAN]

It's a needle in a haystack but a good indie will do a live stream diagnostic to try & narrow it down. As Robbo said MAS is public enemy #1 Good Luck

 

[sunil]

thanks G-man / Robbo ........... will keep you/all posted

 

[jberks]

Mine did the same.
No power and shaking at idle on a 240 is safe (emergency) mode so it's detected something. No warning light came up on mine, it just ran like a trabant. MAS is 99.99% the most common cause. Could be O2 sensor though, both went at the same time on mine. Replaced both and she was sweet as a nut again.
I've also had lots of problems with plug leads on the E240 - they generally lasted me no more than 3 years a set - but cause slightly lumpy idle rather than safe mode engaging.

 

[sunil]

Thanks Jberks,seems same prob with my car,

firstly NO signs of mis-firing or lumpy idle while driving to garage :O( just the usual slight shaking of the engine on tick over as always before( was hoping the car would show the same probs as it did yesterday )

anyway took car to garage (merc specialist) after putting it on the diagnostic comp, the fault came up "STORED in memory" as cyclinder 4 NOT firing, altho car showed NO signs of any probs during the 40 minute drive to the garage

The garage changed both HT leads to cylinder 4 ........ then upon starting car, the car was shaking badly again :O( after putting the car back on comp it showed up same fault on cylinder 5, the threshold should be 2.9 so "he said" but the cylinder 5 was over 3.4 (whatever that means) so again the HT leads were changed for cylinder 5

total £115 for leads, comp diagnostic and labour .........

Garage said that normally the cause is HT leads, as never been changed over the 5 years they become weak ......
I asked about the MAS/MAF being faulty, he replied it is a possiblity, but it did NOT show on computer, which can happen .... was NOT happy with his answer :O(

anyway car seemed fine on drive back home,picks up well, seems smoother,however the slight shake is still there ......

Im not TOTALLY conveniced the garage has solved the problem so have decided to take advice and buy a new MAS sensor via a company on EBAY ....... works out about £58 including delivery

will fit this in upon arrival in 2 days, mean time will drive car, see how it performs .......... will post as how the car performs later

 

[television]

If your car is a 203061 car, there is an issue with moisture getting into the crankshaft sensor.

Malcolm

 

[jberks]

Sunil
I can't recomment strongly enough, getting the full set of leads changed.
I bought my E240 at 12 months old and 10k on the clock. The idle was one of the things that drew me to it. It was totally smooth and inperceptible, I genuinely had to look at the tacho to see if she was running. After about 4 years, I pulled up at the lights one night and she juddered. After that, there was a slight knock at idle. After 4 visits to the dealer, finding nothing each time, the mechanic came out with me. His conclusion is that 'they all do that'. I didn't accept this. Something had changed and with only 24k on the clock it had to be electrical. I then tried a specialist and got the same answer. After almost a year of getting this line, I was at the specialist and whilst talking to him with the engine running and the bonnet open, she suddenly missed a beat and then went back to the normal knock. He agreed this was unusual and booked it in again. After 3 days investigation, he called to tell me he was embarresed. He'd tried a new throttle housing, various sensors etc with no change. Finally he swapped all 12 leads even though he had no reason to suspect them. Hey presto, she purred again. He said he didn't know they ran like that and was going to have a look at a couple of others on the forecourt!
The problem came back after another 3 years and 60k. Another set of new leads and she was back to normal again.

My point to all this waffle, is that your engine should purr at idle. Most were bought new, run for 3 years and traded back in. Hence as the deteriorated around 3 years, the old owner didn't care and the new one didn't know it wasn't right. Mechanics see them like this and assume it's a characteristic as the miles pile on - just an age thing. It isn't!!
If 2 leads have gone, the rest are duff. It's the problem with twin spark, an intermittent weak spark on one cylinder won't produce a detectable misfire, just a slight judder you'll feel at idle. Change them all, (and the plugs if necessary) and you'll have a different car!

 

[sunil]

Dear Jberks .... you are 100% correct,
I had 2 sets of leads changed as mentioned above, and then decided to go to Euro car parts and buy rest of the HT leads, as they were cheaper then buying from a merc dealer ( £25 each single lead from Merc) ........
I changed all the leads and hey "presto" the car is like new!! very very smooth, picks up fast, idles without any missing at all ......... I just got a new MAF and fitted that as well, but I can asure you I probably didnt need the new MAF as the car was after changing the leads fantastic to drive :O)

Its silly that a car manufacture such as Mercedes, make HT leads that only last 3 years, my old ford Rover 820si and previous BMW 520sei NEVER needed HT leads to be changed and these cars were over 10 years old ........ not to mention the Time and Temp LED in the dash on the Merc which now has started to loose pixels ......

Still Im happy I have resolved the problem and the car is a dream to drive now ...... regards ....... Sunil