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The Bosch part # is 0 242 229 659. Any of the below Bosch model numbers would do -
14F8DU / 14F8DU0 / 14F8DU4 /14FR8DU.

If putting in the company specified plugs don't fix this problem I would urge you to examine the tappet valve clearances / take off and clean the throttle body.

Thanks Prozac! Any idea if they are resistive or non resistive? Also Is there a need to check valve clearance as it has hydraulic lifters? The lifters on the car make sound briefly when starting up..say like a second and a half. If yes then what are the valve clearances?

Ok, so, I struggled to fix a cold start erratic idling, jerky acceleration and the engine redlining at 4000RPM while driving for about 3 years and the suspects were (By the way I drive an E200) -
1. Throttle body and a spring that connects a roller on it to clamp in the engine bay (this helps activate a microswitch on the throttle body which maintains the idling RPM)
2. Fuel pressure regulator
3. Ignition coils
4. Intake manifold pressure
5. OVP relay
6. Valve tolerances
I put in a new throttle body, fuel pressure regulator and found the OVP relay to be alright. I sourced new ignition coils too. The problems persisted till I found out that this brilliant mechanic who for reasons best known to him put in the old faulty throttle body had conveniently forgotten to attach the spring I talked about just now. Upon fixing this spring and the new throttle body back the idling issue disappeared.
However the jerky acceleration persisted and an adjustment of the valve clearances (cylinders 1 & 4 were not ok) solved this problem to a certain extent. The 4000RPM redlining still persists and I shall now try changing the ignition coils.

I would therefore in your case suggest you start with the simplest and then take it from there -
1. Clean throttle body and make sure the spring has the right tension. Even a 1mm gap between the butterfly valve and housing can cause issues (when throttle is closes).
2. Check/clean your air mass sensor (the E220 has one, mine doesn't)
3. Check the OVP relay - this provides voltage to the ABS and ECU thereby running the cold fuel enrichment and idling circuits (to increase RPM when engine is cold and decrease when engine is warm). When these 2 circuits don't operate the engine runs poorly. So, check the 10A fuse on the OVP relay and clean terminals/contacts if rusted.

Only if the above don't work then would I suggest looking into the other suspected culprits - intake manifold pressure/leak, ignition coils, valve clearances.

I have OEM MB plugs lying in my cars boot.
Last year i went to Sood Motors Palika Bhawan, and he gave me 4 Bosch plugs, installed them, and they are working good since then.

Thanks guys for the detailed information. ..will dig thru it !!

I had a similar problem on my E250 D and I had temporarily sorted out the issue with a battery cut off switch and across this switch I kept checking what the current flow causing the drain was; after a detailed observation I felt it was the comfort convenience module under the rear seat. I replaced the same as a unit and the issue vanished. There was some diode within it that was permitting a drain in this unit I feel, as on reconnecting the old unit I noticed that the windows would roll down if I held the key in the drivers door in the "open locks" position whereas it is expected only to raise the windows in with the key held in the "close locks" position.
I have had no problem since over a year and a half after I replaced the comfort control unit.
Please check out your current drain. The only drain that should exist is that of the clock which is very negligible and in milliamperes and will not cause the battery to run down in weeks. Battery capacity of 62 Ah would mean at least 500 mA (6 Watts @ 12 volts potential Difference) drain exists if the battery was to go flat in 124 hours. is your boot lid light not shutting off ? Best way would be to begin by checking the current drain and then looking for the leakage corresponding to the value of the current. All this after assuming that there is no internal short in your "New Battery" !

Guys as Viraat suggested me to post my queries in this thread,

I am a college student who's saving up some cash to buy himself a W124. The purchase will happen in couple of months but I am just gathering information whether I would be able to enjoy the vehicle or not...

So the requirements are:
My daily drive is from Dwarka to Noida and back which is roughly 80-90 kms per day so that means I can only get the E250D. Secondly I would like the Automatic variant as it will make it easier to handle the ever increasing Delhi traffic.

How much FE would I get? And can the car handle such daily use without giving any problems?

Experts please help me out.

Keep aside atleast 50k short term for servicing and restoration. It all depends on the condition u get the car in, the figure could be much higher In my opinion the E250D automatic is a total slug as compared to the E220. Hope u have driven one before. Not sure about the FE for diesel..the only recurrent problem I have with my car is that the fuses lose contact at times due to corrosion at the ends...so one thing or the other just stops working at times..just nugde the fuse n it works..makes sense to replace them all but plain laziness is stopping me to do so..

The car shouldn't give u any surprises after all initial repair and restoration is done. Like I said depends wholly on the particular car u lay ur hands on...all the best

Have you driven a W124 before? The 250D automatic is a slow starter, but once it gets moving, it does pretty well. The automatic can have a lot of problems of adjustment and so on, so expect any car you test to have uneven shifts and so on. The fuel economy is around 12, from what I remember.

The number one problem you will have with the E250D Auto is FINDING ONE. I've come across 3 in 5 years. I bought one of them, and then sold it a few months later for another 124. I occasionally regret selling it, as it was an excellent car for the city. Lazy up to 30 km, but incredible torque and loads of fun. A wonderful cruiser too.

No I have not driven a W124 before. Been a passenger once but not enough to gauge anything.

The auto is that rare? Damn. And how much can one go for in a decent state which can complete my requirement easily?

You ought to drive the regular E250D first and see what it is like. There are plenty for sale at any given time. The good part is that you don't need to shift gears too often as the gear ratios are well spaced. It might just be the simpler solution. If you absolutely need a cheap diesel automatic and can't find a 124, I suggest you go the Octy/Laura route. Cruze is also available at a slight premium.

Also try searching for 300D Autos. They were equally rare/common.

The prices have become very unpredictable thanks to the NGT stuff in NCR. Should be about 2.5, but could be much lower or higher, depending on the seller.

If I can get one within 2-2.5 I can definitely consider getting a W124. I did find one 300D auto on OLX and it seemed decent nick from pictures uploaded. Seller was asking 2 lacs for it.

Don't forget, the car might be for 2 or 2.5, but parts will still not be cheap. I suggest you test drive a couple of W124s, read buying guides, read this entire thread, and visit some shops in Palika Bhawan and Khan Market after creating a list of parts that you are likely to need at some point, figure out all the costs involved, and THEN go ahead with this.

Thanks for the headsup. Will definitely see what goes wrong and how much it costs. How hard is it to generally procure a spare?

Not really difficult in NCR.
Shops in Palika bhawan will arrange them for you, in case not in stock.
In case you dont find one, you know who to get in touch withlol: