E240 Not Idling Correctly

[GregE240]

Hi,

Just thought I'd ask for ideas before I take the car to the dealer?

My 1998 E240 has started idling erratically over the last week or so. Its especially noticeable when the car is in D and you are at a standstill. If you take your foot off the brake the car doesn't creep forward smoothly, its more jumpy. I'm confident it is not the gearbox because if you put the box in N or P you can see the revs fluctuating, whereas normally the car just sits at a whisker over 500rpm.

Its also intermittent, which is a pain. It can do it when the engine is both warm and cold. Once on the move it is not noticeable at all.

The engine has just over 160K on the clock, and has a full main dealer history. It had a new MAS at 98K, and has been fine ever since.

Any ideas gratefully received!

Thanks,
Greg

 

[television]

Being intermitent its more likely to be bad soldering in the OVR, that's the way they start to go, take it out and solder up/have soldered up, should fix it.

Malcolm

 

[jberks]

Sounds rather familiar, been here with my E240. At the mileage it could be the throttle body. Turned out not to be in my case, but this is a common cause apprently.

It could also be the plug leads. Mine did it every 3 years. Idle would go lumpy and creep in gear would feel like the front disks were warped. A new set of leads fixed it on both occasions. I should add that in my case it wasn't severe enough to show up on the tacho, just the seat.

 

[GregE240]

Thanks both.

Malcolm, any idea how much an OVR is going to set me back? Likewise JB, how much is a new set of leads going for?

Car is booked in at Milton Keynes tomorrow morning.

Funny, I did wonder if it was damp getting in somewhere it shouldn't. Plugs are also about due for change as well, if I recall.

 

[jberks]

Greg,
The leads cost me around £220 ish from memory. Obscene for a set of leads but thats what proper MB ones cost. There are 12 but even so.
I assume they are lined with gold and each lovingly created by hand by highly trained artisans!
If your plugs are due for a change, I guess a duff one might give similar symptoms too. Thats the trouble with twin spark, you don't get a proper misfire to find.

 

[GregE240]

Thanks JB, car was dropped off at MB Milton Keynes this morning. Haven't had a call yet, so either they haven't started on it, or it was something small that is now fixed.

Will update as soon as I know.

Greg

 

[GregE240]

Just had call from dealer.

They've put it on the computer and....

MAS. I had an inkling it might be this as the car has felt a little low on power, and displayed the same symptoms as it did last time it failed, although not as severe.

Ah well, it will be a nice drive home I guess.

The current MAS lasted 70,000 miles. 90 odd out of the first one.

Greg

 

[wportre]

Sorry to be thick but what's an OVR?

 

[wportre]

Got it: overvoltage relay. Sorry.

 

[wportre]

And where is it on an E240? I've looked on the Russian site and on the car. Can only think it is in the back of the engine compartment fusebox, not easy to get at. Is that right?

 

[Ellsy Tanners]

And where is it on an E240? I've looked on the Russian site and on the car. Can only think it is in the back of the engine compartment fusebox, not easy to get at. Is that right?

This car doesnt have one. Its only the 124 that have one. the 210 have a k40 relay which does a similar job.

 

[wportre]

Greg E240: I would bet good money this is plug leads. The Boschs break through the insulation to the metal sleeve after about 30,000 miles. It's a pain to switch them but you can get a set from Euro Car Parts (tell them you're a **** member) for 80 pounds. Cheaper than debugging MAF sensor etc. Air filter box out and tug them out with a cord wrapped round the sleeve. Never found the OVP relay: it was fine. Change the gearbox oil and filter if you haven't already.