M5CLK

'02 totally stock C32 with 60k miles, the car runs smooth and actually fairly quick. Recently at idle, although the idle is smooth but the engine shakes more than usual, I thought it was just the engine support bushings going, but the garage report came back saying cylinder 5 is partially dead.

They've done all the usual, spark wires, compression check etc etc, even cleaned the supercharger and everything seems normal. It's always cylinder 5 even with spark swap so that leaded to maybe ECU problem? But the ECU shop did a reading and all data seems fine...

The garage is out of idea now and my car has been sitting there for three weeks. Anyone heard of similar problem or have any suggestion please?

Gramma_Benz

Check this thread, could be related to your problem?

https://mbworld.org/forums/c32-amg-c55-amg-w203/365480-camshaft-potential-problems-2002-c32s.html

03MBC32

Did you change out the spark coil with another cylinder to rule it out?

M5CLK

Hmmm... My problem seems to be different than the cam issue, my car is made in 2002 which means it a '03 model year for US? It might have the updated cam already I hope..

And yes, we swapped spark coils and it remains cylinder 5, what's weird is I've never gotten any code at all nor misfire...

Zeppelin

So if there is no code how do you know it is cylinder 5?

M5CLK

Because there's no code, they had to test it manually by removing coil one by one and determine by the behavior. All others started to shake like crazy except for #5.

They've already done everything they can, the compression is fine, so that should rule out cam or leak.. And all the injectors are cleaned etc... They're out of ideas and the only thing to do is to get a new ECU? But if that doesn't work, then it's a complete waste of money... Does anyone know where I can get the cheapest ECU?

pointman

Well, a dead cylinder would certainly explain your c32 being "fairly" quick.

Zeppelin

I guess if it were me I would determine if the spark plug is not firing or the fuel injector is not working and then trace the wires back to the ECU. If wiring is good then maybe take it to a dealer and let them replace the part that fixes it. It will cost more but hopefully they only replace what is needed.

M5CLK

My bad, as per my original message, it's "partially" dead, not completely dead, at full throttle, it seems completely normal or I guess it only shuts down when coming to a stop or at idle? That's the other reasons why the garage thinks it's the ECU...

And they've already checked all sparks, injectors etc...

Zeppelin

How rough is the idle. These cars don't have the smoothest idle to begin with.

M5CLK

The idle is actually smooth, but when it's coming to a stop, sometimes it will surge forward slightly, I guess it's cylinder 5 comes and goes at idle speed causing the surge. But once stopped, it shakes pretty bad as if the engine mounts are gone... Other than that, once running, the car is perfectly normal... At least I don't feel any lost of power at all... I'm really out of ideas, can faulty ECU really do this??