kalsingh1

******THIS HAS NOW BEEN SOLVED-SEE TOWARDS END OF THREAD******
Happy New Year Everyone.

I have an 2004 SL55 AMG (R230), which will stall a least once or twice within 5 mins of driving or start of engine, then after that it is ok. It only stalls at standstill or very low speeds (15 - 20 mph) typically at junctions, turnings where I have to take the foot of the accelerator. Then it is ok as long as I keep driving it.
Does not make an difference it the engine is cold or warm. The strange thing is that Star is not detecting any problems, so I am at a loss in the next step. Additionally I am told this car does not have an MAF sensor.

If anyone has experience of this, or know further tests I can carry out to fix this, I would be grateful. Also this car will use oil, when accelerated hard, in case that has some bearing on the matter.

Work So Far
New Petrol Pump
New Petrol Filter
Clean out of Throttle Body
THIS CAR DOES NOT HAVE A MAF SENSOR.

I really hope I can sort this, because I really like the car. I have access to a STAR system.

Many thanks in return.

Rudeney

This might be an issue with the EIS. Mine does something similar where a few times a week it will lose CAN bus connectivity and sort of "reboot" everything. As long as the engine is above idle and the car is moving, it will continue running, but if I am sitting at idle, the engine will shut off. I also have no errors, and other than my hardwired radar detector rebooting and an occasional "replace key" message on the MFD, there are no other symptoms. The only stored errors I could find on SDS are some about "the CAN bus operating in single wire mode" stored in the "Diagnostic System"

bobterry99

Rodney, it seems to me what is needed here and often in other cases is an electronic circuit to monitor a voltage and detect if it has exceeded a range. In this case it could be a very simple circuit that turns-on an LED if the voltage falls below 12 volts. More versatile would be a circuit with a microcontroller (computer) having an Android phone or PC interface. The microcontroller would monitor the voltage and record its maximum and minimum values; through the interface those values could be seen, and if desired conditions that would turn-on an LED could be set. The circuit could be assembled in an hour and would cost about $10.

kalsingh1

This car in question does not have a distributer cap.

Is there anyway to test if it is the EIS is the problem, or any other way to test for anything else.
I have access to a star system, but has I said before, it does not show any faults. Feels like it is impossible to know where to start.

bobterry99

Think about what failures could momentarily interrupt the ignition system or the delivery of fuel. Then devise and perform a test for each.

If the EIS is your problem it is failing by dropping power to "circuit 15" -- the source of power for the fuel and ignition systems. To test the EIS for this you would check the voltage on circuit 15 at the cigar lighter or a fuse in one of the front fuse boxes at the moment the engine stalls or otherwise does not run. I presume your EIS would be dropping-out for just a moment, and that is why I suggested a simple circuit that would monitor the voltage on circuit 15 and detect a drop-out. Alternatively, you could connect a multimeter that records maximum and minimum voltage readings.

Rudeney

In my case, I have no errors stores in the ECU, EIS, or any other system. The only error I get when I scan the "Body" -> "System Diagnosis" and then I have errors that various CAN bus components are in "single wire mode". My understanding is that this is caused by the EIS, since it's the hub for the car's three CAN buses. I have taken mine out and cleaned all the contacts and looked for any obvious damage, but that did not help. I guess one day I'll replace the EIS, but its not enough of a nuisance to spend the money on it.

Aussiesuede

A shot in the dark here, but do you experience any issues when you "floor it"? A typical sign that the Accelerator position sensor is failing is the car going into limp mode when you floor it, but a faulty sensor can also produce an error if you let off the accelerator too quickly as the car vassilates between deciding upon congested driving mode, a potential emergency stop, and normal. The accelerator pedal sensor syncs up with the throttle position sensor, and if either is not where it expects the other to be at a given point in time, strange things happen. Usually it's limp mode, but it might be worth checking just in case? Generally when you restart the engine, the symptom disappears. If you have a portable scanner handy, try to search for a code BEFORE restarting the engine, so the code doesn't clear itself. You'll be looking for code PO123, but it'll only show when active and reset once the engine restarts - making it sometimes elusive to pin down. Again, just a shot in the dark.

kalsingh1

Essell55mb

Crankshaft position sensor ?

bobterry99

I have the notion crankshaft position sensors failures correlate with temperature (warmed-up engine), and the engine can not be immediately restarted.

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kalsingh1

I have no idea if some has remapped this, is there any way to find out ?
I have tapped a multimeter to the cigarette lighter, to see what happens to the reading on a hesitation or stall. The car seems to have a personality, as if it knows it is being watched, so is behaving itself. Although this morning it had a quick hesitation once only, but the multimeter still seemed in the range of 13.95 to 14.06 volts. I did not see a massive drop. I am waiting for it to stall, so will report back on the multimeter readings.
Has the cold weather got anything to do with, why it is behaving so far ?

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kalsingh1

I have had the multimeter on the cigarette lighter for the last couple of days, and have had two stalls, with no voltage drop noticed other than 14v when running, and 12v when stalled.I have access to star, is there any way now to connect this, and keep an eye on the fuel pressure, if so does anyone know the sequence on the menu ?

kalsingh1

Unfortunately I do not have a ELM327, I understand you need a Andriod phone to run this ? I have an Iphone.

next2pool

Could it be the torque convertor clutch not releasing? Putting it in neutral as you approach a stop may be a clue.

kalsingh1

No its not the clutch. As the car will also stall if left idling in park.

The car has stalled another couple of times, once on a roundabout, the voltmeter did not show any massive drops. I am getting a bit fed up now, just need to get to the cause of it.
Anyone knows anything else, or any further tests, I can get access to a star system from my mate.

bobterry99

I presume if the EIS is at fault the voltage goes low to shutdown the engine only momentarily, and by the time you look at your meter you have missed the glitch. That is why I suggest you monitor the voltage with a meter that captures minimums or build a simple circuit. But since you have access to Star Diagnosis, there may be another option.

Star Diagnosis can monitor most analog signals and display them graphically. The voltage on circuit 15 is what you are interested in. The menu path is something like: control units > Motor electronics > Development data > Actual values > Complete actual value list. If you suspect the fuel pressure or something else is the cause, they can be added to the graph as well, though it may take some time to find what you want since everything is in German.

Rudeney

If this is caused by the EIS, I don't think you;d see voltage drops. The EIS will cause a CAN communication error between the B and C buses, and that's what shuts down the engine.

bobterry99

How sure are you?

If the CAN is the failure mechanism then I would think there would be a status set that he would see in Star Diagnosis, yet he sees nothing. Moreover, would you suppose the CAN error would interrupt the flow of data to the Star Diagnosis PC?

Rudeney

In my situation, there are absolutely no stored errors in any system except that "System Diagnosis" area where it says the CAN bus was operating in "single wire mode". Of course I've not run SDS on it while it "burps" because it happens so rarely, like maybe once or twice a week.

bobterry99

The engine can not be started if it loses CAN network communication with the EIS. But once it is started, if that communication were lost the engine could run normally, and intuitively, for safety reasons Mercedes engineers would not choose to have it quit. And yet if I am wrong and it would quit, then surely it would log a diagnostic code; e.g., "P207D No or incorrect CAN message from control unit N73 EIS Control Unit".

We know from other threads a faulty EIS can cause the engine to quit. In every case I believe the mechanism is a power interruption to the ignition and fuel injection circuits on Circuit 15. The vehicle electrical system can not distinguish between this electrical failure and the driver switching the engine off with the key, and this is the reason no errors are logged.

Aussiesuede

Out of curiosity, when was the last time you changed the batteries in your key Fob?

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Rudeney

In my case, when this "burp" happens, the engine will shut off if I'm sitting at idle, but if I'm moving over about 5mph, it will keep running. Next time I get a chance, i'll go pull codes and post the actual messages, but there are NONE in the ECU.