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Stalling

4K views 17 replies 8 participants last post by  W124Cabrio 
#1 ·
I have owned my 2007 SL 550 for almost 3 years and suddenly yesterday the engine stalled at low speed and the dash lit up as if I had just turned the key.
I restarted but this happened twice more before I got home.
There is no Check Engine Light or any kind of message.
I have read in this forum that the EIS might cause this symptom but since I have Keyless Go I never use the switch in the dash.
Both batteries have been replaced in the last 12 months and the charging system seems to be working as expected.

I do not have SDS yet but while I wait for it to arrive are there any other clues I should be looking for?
 
#3 ·
I had a similar issue where car engine stopped while driving, it happened to me 3 times over the last 3 years, at first from reading and researching I though it was the EIS, had it changed and then had this happen once.

There is a thing I have on my mind, I remember almost 7 years ago when I had a SLK230 there was a similar issue due to a dirty MAF sensor and the solution was to spray it with a MAF cleaner, another thing I am suspicious of is TPS sensor but I had mine replaced.
 
#6 ·
You can simulate stall caused by MAF by hand block the engine air intake, or unplugging the MAF, the car stalls, and SRS light comes on...

The fact that all lights are coming on, points the fingers back at the EIS

Need codes to tell for sure, both problems with throw codes
 
#7 ·
SDS has not arrived yet (sigh) but the delay has given me time to focus on the clues.

1) This condition only occurs after at least 15 minutes of running.
2) Only happens when my foot is off the gas for a period of time - e.g. coasting up to a red light.
3) The appearance is that the ignition has been switched off and on momentarily - engine often refires by itself and dash display goes blank then returns to normal although the air bag indicator delays before going off as it does after a cold start.
4) Sometimes the CEL comes on and will stay on for a few normal starts and then disappears.
5) Sometimes (maybe 30% of time) a red battery warning with no messages will appear after the incident but does not reappear on the next start.
6) Both batteries (replaced in the last 2 years) have normal voltages under no-load and show increased (charging) voltage when engine is running although the consumer battery voltage seems to fluctuate when charging (maybe normal for the type of battery?).
7) All battery connections are clean and tight.

Does this sound familiar to anyone?
 
#8 ·
I'm still going with bad EIS. When you do get SDS, you will probably find no errors except in the "diagnostic system", which will tell you the CAN bus has a ground fault and switched to single-wire mode. Classic EIS failure symptom.
 
#10 ·
Not at all.
In fact if the engine is at a reasonable speed, say above 1200 rpm, the engine fires up again before the crank has spun to a stop without me touching anything. It just feels as if someone flicked the ignition off then immediately back on again.
 
#11 ·
Brandon asked about ease of restart because of doubts over the CPS, however, if the car is easy to restart, and dash is acting that way, I vote for EIS as most likely cause
 
#12 ·
I'm not suggesting throwing parts at your car, but I'm inclined to agree with bayhas: replace the EIS. A coupla years ago my R230 suddenly developed a number of odd problems: wiper switch wouldn't work wipers, but the headlight dimmer function worked OK; rollover bar symbol was always displayed on dash, but rollover bar switch wouldn't work the rollover bar; horn wouldn't work; cruise control wouldn't engage ... maybe some other stuff I've forgotten. New EIS cured all the ills.
 
#13 ·
I now have my Star C3 and cleared out at least 3 years of codes and started again.
Quite often it either can not communicate with the EIS or tells me to replace the passenger side SAM but other times says everything is ok.
There have been several faults indicated for the crank position sensor and being the cheapest item on the list I changed it yesterday. Interesting that the new part number is quite different from the original. Maybe it was occasionally giving a faulty reading which would stop the engine. I drove for an hour today with no problems but time will tell.

In the meantime, I am still suspicious of my consumer (rear) battery and found a useful procedure in the WIS to monitor the battery voltage.

"Switch on ignition (position 1). Ensure that displays for trip odometer and temperature appear in basic menu (cycle through displays if necessary). Push the reset button on the instrument cluster 3 times within 1.5 seconds."

After this a beep will be heard and the battery voltage will appear in the tach display. The voltage will display until the ignition is switched off.
Continuing to turn the key will start the car so it can be driven normally while monitoring the system voltage.

I have watched this for several miles and observed some odd results.
Charging voltage is 14.2v at all engine speeds.
From a stop, as soon as I touch the gas pedal, however gently, the voltage drops to 13.4v and stays at that level until the 3/4 upshift. Downshifting to 3 or 2 does not cause a voltage drop.
Applying the parking brake with D selected then touching the gas causes the same issue.
Touching the gas in P or N has no effect on voltage.

Can someone maybe try the same tests and let me know if this is normal? What could be dragging the voltage down?
 
#15 ·
From a stop, as soon as I touch the gas pedal, however gently, the voltage drops to 13.4v and stays at that level until the 3/4 upshift. Downshifting to 3 or 2 does not cause a voltage drop.
I suspect what you see is entirely normal for your car. The voltage regulator and thus the output from the alternator is variable and controlled by the engine management electronics to adapt to different conditions in order to extract more performance and economy from the engine.
 
#14 ·
Using SDS, go into "Control units" - "Body" - "System Diagnosis". Scan codes, and I suspect you'll find several regarding "communication of xxx is in single-wire mode". Although it could be a CAN wiring issue, when it's intermittent like that, it's usually a bad EIS.

As for voltage, you really should be seeing 14v once the engine is warmed up. You may seem some very brief (1 second or less) fluctuations, but it's usually 14.1v.
 
#17 ·
My problem appears to have gone away.
I replaced the crankshaft position sensor (my hands will heal soon) and all has been quiet for over a week.
There may also be an issue with the rear battery which I am monitoring.
Maybe when the CPS caused the engine to die the sudden drop in voltage at the consumer battery caused a bunch of low voltage faults to display.
Right now there are no codes showing as long as the engine is running while I run the tests. Time will tell.
 
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