E240 Engine not Idling Correctly....

[GregE240]

Just thought I'd ask for ideas before I take the car to the dealer? Its booked in tomorrow, but just wanted a heads up....

My 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

 

[tamrsoft]

Sounds like a possible air leak somewhere between the MAS and the inlet manifold. Check for loose or split rubber hoses or connections or poor joints around the throttle body area.

 

[shandy]

First of all try cleaning the throttle body and butterfly ,they get contaminated with oil over time as the cambox breather vents into the airduct before the throttle valve , this can close the airgap and cause the management system to compensate ,thus causing the uneven tickover. Worth a try at no cost but your time.

 

[GregE240]

Thanks chaps,

Other suggestion I've had is dodgy plug leads. I've never changed mine. Also, its getting near new plugs time <wince>, but in the past a plug set change has made no difference to the performance of the car at all.

Its intermittent as well, which is a real pain.

Ah well, we'll see what the dealer says tomorrow I guess!

Greg

 

[Shude]

First of all try cleaning the throttle body and butterfly ,they get contaminated with oil over time as the cambox breather vents into the airduct before the throttle valve , this can close the airgap and cause the management system to compensate ,thus causing the uneven tickover. Worth a try at no cost but your time.

More information needed please!

I am going to attempt to clean the throttle body on my car to see if it makes a difference to the miss-firing problem it's had for a while now.

Please can you explain where the throttle body is and what I should clean it with etc

 

[shandy]

Shude,
Not sure about the layout of your engine but the throttle valve will be between the airfilter and the inlet manifold , disconnect the duct from the air filter side and you should see the butterfly throttle valve ; a flat circular plate with a spindle across the centre. To clean use a brush soaked in solvent ;meth spirit,ipa or similar (wear rubber gloves);clean the butterfly valve and the throat of the valve then wipe off residue with a non fluffy cloth or paper towels(you'll be surprised how dirty it is).
Then hopefully ,reassemble,start your engine and listen to how smooth it's ticking over.
Geo.

 

[GregE240]

Dropped the car off at MB Milton Keynes first thing this morning. Haven't heard anything yet. Will update as soon as I know anything.

G

 

[GregE240]

Just had call.

MAS.

Had a sneaky suspicion it might be as over the last month or so it had displayed the symptoms - slightly poor pulling power, gearbox feeling a bit rough.

Oh well, it'll be a nice drive home I suppose.

The car had a new MAS around 90,000 miles. So just over 70K out of this one.

 

[GregE240]

Well, Its Not the MAS......

Driving into work this morning, slowed for a roundabout and......oh no. Same problem.

Phoned dealer back who said they also found a fault code on the gearbox, so they reckon it might be a faulty control module. Now, I'm sorry, but I just don't buy this at all. The engine is misfiring, for goodness sake! I've spoken to my mechanic (ex MB), who reckons its more likely to be either a coil pack or a plug lead thats gone south. The car will be with him on Monday, and he will plug it into the Star machine and take a look.

Greg
Not happy and certainly £400 less happy.

 

[shandy]

Greg,
Did you get you original MAS back with your car from the dealer, I would go back and ask them to refit the original and refund your costs, why should you pay for their incompetence? They are the "experts" and charge accordingly.

 

[GregE240]

Well, the car is actually booked in with them next Wednesday - its the soonest they could see the car.

However, I'e been recommended an indie with a Star machine here in MK, so the car is off there at lunchtime for their opinion. The owners are both ex MB so we will see what they say.

Their money is on coil pack or plug lead, likely the latter. Strange as that was what my mechanic said too.

We shall see.....

I agree though, its incompetence on their part. And if they've binned my old one, then tough s*** - I shall be wanting money back.

 

[Shude]

I agree though, its incompetence on their part. And if they've binned my old one, then tough s*** - I shall be wanting money back.

This is why I am reluctant to get mine sorted out, I just know I'm going to have to replace most of the items in the engine bay to get it sorted.

I have had all kinds of suggestions so far, MAS, crankshaft sensor, fuel pump, throttlebody, ECU, gearbox sensor etc and we're talking about £2500 of parts there with the possibility of none of them actually fixing it!

 

[Will]

Shude, would you like to borrow a spare MAS for diagnostic purposes? I changed the MAS on my C230K because I found a brand new genuine boxed MB one that was cheap (kept the old one as a spare). If you can check the part number I'll happily lend it to you?

Fitting takes all of 1 minute

Will

 

[Shude]

Shude, would you like to borrow a spare MAS for diagnostic purposes? I changed the MAS on my C230K because I found a brand new genuine boxed MB one that was cheap (kept the old one as a spare). If you can check the part number I'll happily lend it to you?

Fitting takes all of 1 minute

Cheers, we should try it at a GTG! Unless you want to post it...

I am going to insist that any parts replaced at whitefield from now on will require my inspection before being disposed of. In fact I'm going to request that I get to keep EVERYTHING, all filters, nuts, bolts, washers, fluids and everything. Damned if I'm going to pay them to dispose of the engine oil when I can dispose of it myself for free at the council tip.

I was talking to one of the younger service guys at Whitefield and he said he has a W202 as well, he wanted a MAS to try out on his car and they had none spare and wouldn't let him order one to try out - so you can imagine I had no luck with the same query. This isn't a warranty car where they can bill all their diagnostics, testing and cockups to DC, it's a personally owned car and every penny comes out of my pocket!

 

[GregE240]

Well, the car has just been on a STAR machine at this indie in MK.

Nothing. No codes stored at all.

Been advised to keep an eye on it, if it reoccurs get it back down there sharpish.

<sigh>

 

[Shude]

Nothing. No codes stored at all.

Mine had one fault logged: diff-lock. That fault has never come back so it's obviously not that...

 

[Will]

Cheers, we should try it at a GTG! Unless you want to post it...

I am going to insist that any parts replaced at whitefield from now on will require my inspection before being disposed of. In fact I'm going to request that I get to keep EVERYTHING, all filters, nuts, bolts, washers, fluids and everything. Damned if I'm going to pay them to dispose of the engine oil when I can dispose of it myself for free at the council tip.

I was talking to one of the younger service guys at Whitefield and he said he has a W202 as well, he wanted a MAS to try out on his car and they had none spare and wouldn't let him order one to try out - so you can imagine I had no luck with the same query. This isn't a warranty car where they can bill all their diagnostics, testing and cockups to DC, it's a personally owned car and every penny comes out of my pocket!

No probs, drop us a PM and I'll post it to you if you want? Might be quicker than waiting for the next GTG where we are both in attendance

If you can check the part number I'll try an cross-ref it with yours?

Will

 

[Will]

I'm pretty sure the Bosch part number, as stamped onto the MAF is "Bosch 0280 217 114"

HTH,

Will

 

[GregE240]

Update

Well, the car is actually booked in with them next Wednesday - its the soonest they could see the car.

However, I'e been recommended an indie with a Star machine here in MK, so the car is off there at lunchtime for their opinion. The owners are both ex MB so we will see what they say.

Their money is on coil pack or plug lead, likely the latter. Strange as that was what my mechanic said too.

We shall see.....

I agree though, its incompetence on their part. And if they've binned my old one, then tough s*** - I shall be wanting money back.

Just got the car back from MB MK.

Diagnosis? Spark plugs need changing (been in for longer than 50K), and 3 out of 12 HT leads are showing high resistance.

Car will be booked in for remedial work once the leads are in stock (thanks Jimmy, I don't think I'll be needing yours now mate).

Although I didn't speak to my service manager, I told the gentleman I dealt with that I would be asking for a considerable reduction on the remedial work as in my opinion a MAS sensor was replaced when it clearly did not need doing.

Is that fair enough? I am £400 down as far as I can see with a car thats still misfiring at idle.

 

[marc1]

I have a C180 petrol auto 1996 N reg, when I start the car from cold I have to use both feet to drive until it warms up,seems like the choke or what ever it's called now,isn't coming on.Just had full sevice and it's a mystery to the garage too,they cleaned the carb etc.it's done 163000 miles, I do between 450 to 700 miles every week on long runs mainly. Don't really want to go to the main dealer because it cost's stupid money and then you don't know what they have really done and what was really needed. hope someone can give me a few clues to check, thanks. Graham