A1EK

Hi guys

I accelerated hard just having some fun this afternoon and when I started to slow down the car became lumpy like its stuttering. It doesn't stall but at Idle it is lumpy and as you accelerate it feels stutter.

Thoughts are I have sucked up dirt into the injectors perhaps?
Or has one of the spark plugs failed ?
Has something inside the exhaust come loose causing it to be chocking the engine?

I have disconnected the MAF and the symptons are still there so I the MAF is fine.

Any other thoughts?

fd3

I have the 02 c230K and I had the same problem. In the past it was a recall issue where the car was literally stalling out. There was oil getting into the ecu and other parts. The dealer took care of it. However I still have the problem when I am heavy on the pedal. I notice it the most with the AC going.
Only thing I can say is that it may be a good idea to just take it easy and to not really gun it until you're already going 20 or so. Also if you shift into neutral while you are waiting a light it stops the engine grunts.
Hope this helps.

dlbehrns

No check engine light?

A1EK

Sorry this is similar post I started at the beginning. Fortunately my car is all fixed !

Turned out one of my ignition coils went , I replaced it which stopped the lumpy ride, but my Super charger was not behaving properly. I found that one of my MOSFETS has blown on the ECU, so after soldering a new one, the car works perfect again !

GatorMB

Wow,
That's quite a find and repair, Its likely most of us will not attempt a DIY repair like that. The ECM internal schematics have been kind of non existent even on older models. I have done some searches on the micro-controllers chip internals and had no luck.
Something must ave allowed the mosfet to fail like a buck regulator or some foreign matter like tea/brew/rain. (hunch)
The WOT event would point at the mass sensor, throttle sensor, Hung clutch on the Kompressor.
Mabye the failed coil fed back into the mosfet?
Great fix, did you photo any ECM internals?

Gator

A1EK

Thanks Gator

The problem I had was that an ignition coil blew a couple of weeks ago, I replaced this and the car then ran smooth with no misfire. However I noticed that the supercharger was not behaving. It was always on and did not engange and disengage when you reved the engine passed 2300 rpm as it should.

I knew the MAF was okay as I tested the car with another, the crank position sensor was good as otherwise I would have issue starting. I took it to a guy I know who did a diagnostic and said that the electromagnet in the supercharger was not responding and that the whole supercharger would need replacing as you could not get the part separately.? I still was sceptical that the electro-magnet was the issue as it engaged and disengaged when I pulled the plug to the S/C . This is when I knew it had to be a 'control' signal issue.

Searching the forums I I found some interesting ideas on the SLK board which use the same engine, someone had talked about a MOSFET on the ECU needing to be replaced as this gives the grounding that allow the S/C to engage and disengage. So I bought one of ebay for £4.99 and replaced the one on the ECU and the Supercharger now works a treat !! It was going to cost me £400 to get a second hand unit fitted, what a waste that would have been!

I am not taking the credit here as thanks goes to:
Dandywarhol, Subby MrKatz and Barchetta for getting me in the right direction !

If your interested I have added some photos and videos of the results....

Thanks again guys , this is why this forum is so good !

Testing the MOSFET for the 1st time.
- By pass valve functioning gain.
- Out for a drive with Supercharger on.

cornbeef

hi i changed the mofset over but there was no change the clutch still would not work in fact the car would not crank till i changed the k40 then the car started but the clutch still would not work

A1EK

Fortunately the CLK does not have the K40 issue, there is no fan cooling to the module.

Have you opened up the rear of the K40 circuit board to see if the solder joints are okay?, I have seen that they can work lose.