W208 CLK ECU problem

[666bxg]

Hi...

My wife's car, a CLK200 recently broke down and was misfiring. Probably only one or two cylinders were running at that time!

Took it to our local independent and was told the ECU had fried! Luckily he managed to source a 2nd hand one for very little money (€250). The car also had a B service and its running beautifully now

Are ECU failures common? And any problems I can expect running on a 2nd hand ECU?

cheers

 

[Dieselman]

They can just fail and also the high voltage ciol packs can cause a spike which fries them.
It MAY be worth changing the coil packs as a precaution, or at least check the condition of them and the HT leads, as any HT voltage not used by the spark plugs goes back to the ECU.

Probably the high power transistors for a coil pack were blown on the original one. Cheap fix if you can obtain the correct ones or try BBA Reman.

 

[sstylos]

I don't know if this is your case, but this problem is caused by engine oil travel throuht the wires.

Please check your wires if they have oil.
If they have oil, this is the case.
Then you may have to replace these cables too.

There is an "Oil Trap" cable that you add where cables connect to engine.
From my experience not all the services/mechanics know that.

I would suggest the "Oil Trap" part on all W208 with 2000cc engines
or MB with these engines

Stelios

 

[Japtastic]

This is exactly what happened on my CLK 230K, luckily it was spotted before the ECU got fried! I replaced the parts with all the new modified ones and all seems to be fine now, it did fry the O2 Sensor...

 

[aka$h]

I don't know if this is your case, but this problem is caused by engine oil travel throuht the wires.

Ive heard of this too, seems a little far fetched but it is true.

 

[666bxg]

I don't know if this is your case, but this problem is caused by engine oil travel throuht the wires.

Please check your wires if they have oil.
If they have oil, this is the case.
Then you may have to replace these cables too.

There is an "Oil Trap" cable that you add where cables connect to engine.
From my experience not all the services/mechanics know that.

I would suggest the "Oil Trap" part on all W208 with 2000cc engines
or MB with these engines

Stelios

I'm very sure my indy didn't change anything else apart from the ECU alone.

Can I check this wire myself? More importantly will I be able to change the wires or coil packs as a DIY?

thanks for the replies

 

[sstylos]

To check if your cables have oil, unplug cable connectors and check them for oil.

Even if they don't have oil, and this is not your case,
I would add the "oil trap" cable to avoid this happen.

It happened to a friend of mine, and it was an expensive repair (cables+ECU+etc).
My cables had oil, but thanks God, didn't damage my ECU.

Stelios

 

[sstylos]

Oil trap cable is cheap, and that is why I suggest it, to avoid a big damage.

Stelios

 

[Japtastic]

I was trying to find the part number but can't find it, Mercedes are aware of it and there is a revised part to change to stop it happening again, cheap as well, from memory it goes somewhere near the crank/cam? angle sensor...

 

[gazz]

The part in question is on the front of the engine. It is on the end of the cam, under a cover .The later engines have 2 cam adjusters, the earlier ones only have one on the inlet cam. It is worth getting the mod cable, even if the plugs are wrong. You can cut the plugs off and solder the oil-stop part into your loom. The part you require is bizzarely called 'starter line' and the part number is MA271 150 27 33.

 

[bassfreak]

Oil just ruined my new Bosch replacement O2 sensor. I knew I had oil in the ECU harness but I believed it was ATF oil from the known-common-issue of the possible faulty AT connector, but I was unaware of the cam magnet connector common-issue. I had oil dripping from the connector and along the edges of the cam magnet at the front of the engine. I found that comparing oil smell from the engine with the oil smell on the cables. Seemed to be the same and when unplugged the cam magnet connector oil dripped from it.

Until I will buy new cam magnet and the said oil trap cable, now I soldered wires directly to the cam magnet connector pins, filled connector with hi-temp silicone hoping to not allow oil travel, and siliconed in place on the engine. Cleaned connector with nitro-solvent and wires were taped inside the connector to allow easy checking for oil inside. Also cleaned the O2 sensor wires and connector and put back hoping to revive itself. Until then I have to find a replacement O2 sensor because engine is running rough at idle, when I tap the accelerator, seems like misfires when deccelerating and fuel consumption gets as high as 18-21 L/100km/h in urban driving.

 

[johnboyinsole]

Hi, I've noticed the oil too. Do you need to purchase the magnet, or is there a gasket or sealant you can buy?