w203 c220 cdi coupe starting problem

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........I am pretty sure it is not air ingress into the fuel, if it was then you would have lots of grey-ish smoke and it would be lumpy,it would also readily start when the air had cleared.
Excess/unburned diesel will give black smoke at cold.
Remove the g/plug relay and have it tested just to put ur mind at rest.
It may not be that but if it was then it prob would shut the engine down until it had cooled down properly after a faulty heating cycle.
 
would have to look in the manual for it ... hope its easy to fined
how can you test these to see if they're faulty or not?
thanks
 
just read all ur posts!

The comp read out suggests a cold start problem.......which sounds pretty much like I said, deffo get the g/plug relay checked out or better still, borrow one off someone to check it out!
Sorry don't know where your relay is but it is usually situated around the battery/fusebox area.....it will be a sealed unit with a heat sink on one side .......heat sink will have fins on it! should be easy to spot!
 
thanks paul ... i'll look for it tomorrow and see what i can do

lovely cars mercs are but a nightmare if they go wrong lol
 
p.s. ......this relay is not servicable and you will not be able to repair it.

It works like a current rectifier on a motorcycle (to put it simply!), when they wear out on older cars the car will start eventually but you get loads of black smoke until the engine reaches temperature, then the smoke disappears, on newer cars like yours then everything is fed back to the ecu and if it thinks there is a problem about to occur then it will shut the engine down until that problem has cleared......g/plug rectifier gets way too hot before end of cycle,shorts out and sends signal to ecu that exhaust gasses are not hot enough etc and then this inturn turns faults up with other stuff that are not sensing what they should because the engine is not warm enough to keep emissions down etc etc.
For example.......
our vauxhall 1.9 cdti has 2 glow plugs that are knackered, when plugged into the computer it throws up all sorts of things that are not working properly because the initial start is colder than what it should be, I was told it was an ecu problem but I tested the g/plugs and now know 2 of them are knackered!!
Contrary to popular belief, ECU's are pretty well protected against again pretty much that can be thrown at them except for being immersed in water,they are even protected from short circuits (even lightening!!) so I doubt that is the problem.
 
No prob's m8,
Not deffo saying it is that but am 90% sure it is a prob in that circuit somewhere having seen the computer read out......all points to a heating/emission prob.........lol, lovely cars Merc's except for the rust on my model!
cheers.
 
This may be of help to you, but it doesn't give a lot of information and doesn't give any indication as to whether the glow plug control unit is serviceable or not, i.e. relay etc.

It is for C Class 2000 - 2007.

glowplug1_zps43cac8dc.jpg


glowplug2_zps3bb6f3ad.jpg


glowplug3_zps163bbe5b.jpg
 
thank you grumpy ... i have saved what u posted on my laptop for future reference ..

however I've took the ECU out for inspection last night and there was water at the bottom of the SAM front fuse box where the ECU is located and about a 1/4 of an inch of the bottom part of the ECU was wet/damp ... took inside the house , gave it a good wipe and put it near the the radiator from 12 till 9 this morning .. before i put it back in the ECU bay i noticed there was some water at the bottom of the SAM fuse box , i managed to dry it with a help of a little straw by sucking it out using my mouth .. after 5 mouthfuls all water was cleared .. put ECU back in and made sure the SAM box cover was placed tightly back on ... started the car and drove it round the block and all is good and in perfect working order

then did an ECU reset by turning key to second position and pressing the accelerator for 5 sec then turn key to position 0 and waited for 2 minutes

the central locking is NOT working tho , i can still lock the car manually

thank you all for your help
 
That's good news, glad you got it sorted. I'll know where to look if I ever get the same symptoms.

Just in case you decide to check the central locking and need a circuit diagram......

centrallockingcircuit_zpsf124ea0f.jpg
 
wish all grumpy men were as pleasant and helpful as you mate lol

I've just reseated all fuses and car is good as new everything is working as it should

thanks a lot again
 
Good afternoon to you all!

Came up to this forum after searching on google. I have the exactly same problem in my 2004 C220 CDI Sportcoupe. In the 1st days the car had the cold start problem, like you describe it, now i just can't start it. Saw the video, exactly like that.

How can i take the ECU out?

Thanks
 
Good afternoon to you all!

Came up to this forum after searching on google. I have the exactly same problem in my 2004 C220 CDI Sportcoupe. In the 1st days the car had the cold start problem, like you describe it, now i just can't start it. Saw the video, exactly like that.

How can i take the ECU out?

Thanks

you need your wiper blades to be pointing upwards (turn them on and when there up turn ignition off so they stay up)
open your bonnet and the ECU is facing the driver seat.. there is a black water shield cover with 2 plastic turning fixture , remove that and the SAM box plus the ECU is just there ..
pull the ECU upwards about an inch and there are the wiring plastic plugs on top of it ... one small plug and one big one... remove the small one first by pulling a plastic piece that secures the plug in place (you cant see it but you can feel for it with ur fingers ) pull the plastic piece out sideways towards driver side then that will release the small plug... do the same with the big plug then pull ECU out
inspect for water ...if there is any then suck it out with a straw thats what i did , take the ECU in house and leave it near the radiator over night .. hope this helps

regards
 
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Well, I just tested and then replaced the battery for a new one, and everything is smooth now. Thanks anyway.

Cheers.
 

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