RA032023

Hi all! I just bought my first Mercedes CLK 220 CDI 2007 2 months ago and while I love the car, I have encountered quite annoying issue that kinda ruins the mood for me.

Symptoms:
1 out of 20 startups of the car, I turn the key to position 1, 2 and all looks normal but when I turn it to position 3 the car does not start, and shows only the same as it would remain in position 2 (dash lights on). No sound whatsoever. Yesterday I tried holding the key in pos.3 for a few more seconds and the dash lights started blinking for a couple seconds and then turned off. I have reinserted the key and car started normally.

Another symptom, which is more serious, is when I'm driving on a highway, for a longer period of time (never happened within 1st hour of driving yet), the dash lights come up (like in a position two ignition) and it looks like car restarts or something. Once the speedometer gauge dropped to 0 and then went back to 100 kph (60mph) because I was driving at that speeds. A bit scary.
Mind to note that this usually happens when I slow down = for example from 140 to 100kph and I let go off the throttle for a moment.
Once the car even stalled when I was driving on the highway again and slowed down to stop at the gas station. All dash lights on, and car stalled at +-5kph. I reinserted the key and car didn't want to start on a first try, reinserted the key and started normally. After that all was OK for the rest of the drive.
It is weird, because this never happens when I have tempomat on, or when the car is under load - always when slowing down from higher speed.

I'm no expert so it's just a wild guess so don't laugh ath this but can this be a voltage regulator issue? Alternator? EIS-EZS? MAF sensor? Fuel pump?
My thoughts are that maybe symptom n.1 can be caused by incorrect function of the voltage regulator, maybe causing not enought power for the car start up initiation.
Symptom n.2 then intermittently somehow delivering too much voltage causing some intermittent power outage or drop or some troubles for the alternator?
I have no idea how to diagnose this and it seems like Diagnostics doesn't show any errors.

Any ideas are welcome and appreciated.

hofnerpres1

Well welcome to the joys of running an older modern car and that glorious world of the Intermittent Fault. Anything since the late 1990's is a bunch of old laptops connected to an engine and some wheels - that's what you've signed up to so better get armed and educated. If you can find a good local Mercedes specialist be thankful and let them fix it - it will hurt but all old cars hurt. If you want to DIY a good tool kit won't cut it anymore - it's the electronics that need to be mastered. Minimum basic tools are a Mercedes specific scan tool - most folks here use the iCarsoft MB kit and it will read most things. It will not solve everything but point you in the right direction. Second essential - If you need a daily driver buy a Honda Fit - this will get you to work whilst you deal with the numerous baffling things that can occur when you have several aging computers with a design life of 10 years left bolted to a car. Thirdly get a workshop manual and parts program - plenty downloadable from the web for $20. Loads of information on YouTube - most seem to be for the pre 2003 W203 but it's all good. Subscribe to ScannerDanner and Diagnose Dan on the Tube and soak it all up. Whilst used parts are still cheap and around at the breakers I would strongly recommend buying a spare ECM and EIS - ( circa $150 ) with the same part numbers - they can be cloned to your car cheaply if disaster strikes. Not only is buying new parts from MB crazy expensive but they are "Reconditioned". Unless they've changed all the big chips and every component you've just paid nearly $2000 for a polished up second hand part which is only warranted for two years. The EZL is a neat device which will fail and is a major pain since the car is dead and the wheels locked. Removal is messy and expensive and will be on top of the large recovery bill. It's only a matter of time since it relies on a cheap $10 12v DC old school brushed tin can motor which belongs in a kids toy. Suggest you bypass it with a solid state "Emulator" - I like the one from "ECUSERVICES" in Poland but others are available and very popular with the MB Sprinter Van delivery guys here who can't afford to get stranded. Please don't think that MB are any better or worse than other expensive makes when they get older - it's just the way modern cars are built. They used to die from rust but now the electronics get them to the crusher instead.

So enough of this vision of your happy future..... The cutting out and erratic starting fault is sounding like the miniature amplifier circuit in the Crankshaft Position Sensor starting to break down. It doesn't always log enough faults to kick of a MIL on the dashboard. It's not expensive to replace and a known failure on older cars so might be worth starting there. Plenty of information about this on the forums. Don't get too gloomy - only the unlucky owners live here - most cars run along quite well.

RA032023

Thanks, I think I'm gonna have to dig a bit deeper into the issue. I was checking out ScannerDanner's channel and it has some great content. I will definitely spend some more time in there. Even though I'm not sure If I can spend that much time learning about cars electrical components. I'm not so technically equipped

I will try to replace the CPS, it actually makes sense the most probably.. I just heard it's a real pain to replace on w209. Welp, as far as the car is running and drives me from point A to point B then I guess it's all good.

RA032023

hi everyone, reviving old thread.
I managed to record the moment this this happens. some new info:

when the car is sitting in the sun for a while or warms up it does this:
I believe it does this also when driving, that's why the stalling.

Is this an EIS problem or still can be anything else?

Thank you

Petlqko

Hi did yoi find the problem , i have the same problem.The engins shuts off while driving and starts on its own.

LakesCLK

Any update on this please? I have exactly the same issue. Momentary loss of electrics which is alarming gat speed and at low revs cuts the car out.
I have replaced crank sensor and this has not helped. No code
Many thanks for any info!