I have a 1994 E420 w/o ASR, with 139,000 miles. Although the Check Engine light is OFF, my car misses and stalls as it gets hot. This started after I pulled the instrument cluster for replacing a broken odometer sprocket, and the battery was disconnected for a week. I decided to pull all the codes and got more than I anticipated.

PIN 4 CODE 1 (I think it's good)
PIN 6 CODE 25, 26
PIN 7 CODE 6, 11
PIN 8 CODE 5
PIN 14 light dim and steady, no codes
PIN 17 CODE 6 (I think it's the distributor ignition)
PIN 19 CODE 13, 18, 22 (I think I need to replace the camshaft position sensor (CPS))
PIN 30 CODE 3,4,8 (I think these have to do with the airbags)

Where do I find the meaning of these codes? I only found the PIN 19 meanings, not other PINS. Do I need to reset all, then see which sets again, or try to fix whatever the codes refer to? Please help!

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2004 E500 4Matic 138,000 miles

Codes are here - http://www.motodok.com/Documentation/Files/MB/cs1000-mb.pdf

Indeed, just clear them all, or all that you can, and see what comes back. Lots of camshaft codes there. Has you engine wiring harness been replaced?

Thanks for the link. I need to study the document. It seems some pins refer to multiple possible systems. How do I know which applies to my car?

I think the harness is good, because don't see any cracked insulation at the fuel injectors, or at any sensors. I only own the car for 6 years, but I assume the harness was replaced at one point.

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2004 E500 4Matic 138,000 miles

The chassis numbers are in the back, your's is a 124.034. The rest is in the Table of Contents in the front.

I erased all codes successfully. I removed and cleaned the MAF sensor, cleaned the throttle body, and replaced the camshaft position sensor (CPS). I replaced booth ignition coils. I inspected the spark plugs and they are nice and brown, correct type and gap. I recently replaced the plugs, caps, and rotors.

I started the car and still had the same problem. This problem started after I pulled the instrument cluster for replacing a broken odometer sprocket, and the battery was disconnected for a week. In the past, leaving the car off for a week or more caused an initial shaking that cleared up after a few minutes of running. Now it just gets worse with warm-up. From cold start it vibrates, like it's missing a cylinder. The vibration peaks at around 1600-1800 rpm. Then as it gets warmer it runs more rough, finally stalls.

I read the codes in all pins and found the previously erased codes:
PIN 7 CODE 6, 11

I think the fault code table is telling me it's:
6 Starter lock-out/backup lamp switch
11 Fuel safety shut-off to LH-SFI control module

I am not sure I'm reading it correctly, or what to do about them. On page 47 of the document it says W124 should connect to a 16 pin connector, but mine is 38 pin.

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2004 E500 4Matic 138,000 miles

Most 124s are 16 pin but not the V8s which are always 38 pin. The Baum book has a few typos. Neither one of those codes sounds much like the symptoms. Keep deleting and reading codes. The sitting for a while could point to stuck lifter or lifter leakdown which would cause the roughness. You just have to let it idle to work through it. When you say you replaced the camshaft position sensor - singular - there are two, one of each side.

Wouldn't stuck lifters cause a valve noise, which the car does not have? I'm thinking moisture might seep into somewhere over time, and because the car is not used, heat does not evaporate it. The camshaft position sensor is on the driver side front. There isn't one on the passenger side. There is a CRANKshaft position sensor near the firewall.

I am planning to erase the codes, check the caps, measure the resistance of the coil ignition wires, then place a timing light on each wire to see if the ignition is there at times of trouble. Also will try to measure the fuel pressure. I hope I have the correct fitting. Maybe I could tap into the Oxygen sensor circuits to see if there is a closed loop, and rich or lean condition. I hope for some new codes to show the way. Is this a good course of action?

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2004 E500 4Matic 138,000 miles

If it doesn't smooth out in five or ten minutes not likely to be lifter leakdown. The other somewhat common rough idle 119 problem is jumped timing chain. You're checking pins 4, 7, 8, 17 and 19? And getting one flash after erasing?

I had similar issues, and I replaced Distributor caps and rotors, and its fine now.
I still have the check engine light, but its been on for a yr now, and I keep reading codes and replacing what it says in codes, and it still comes back, so now I just ignore it. My car rides like a dream though. Good Luck

Can it be a jumped timing chain and start almost normal with one cylinder missing? I could verify this with a compression test, but it also doesn't have the "popping" sounds your hear when attempting to start a jumped engine.

Yes, I am checking pins 4, 6, 7, 8, 13, 14, 17, 19, and 30. No, I do not get one flash on some of them. Notably no flash on 13 and 19 after erasing codes. Also, the CE light was not lit with codes 13, 22, and 18 stored. The CE light comes on with the ignition on, engine off.

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2004 E500 4Matic 138,000 miles

It could also be bad wiring to what the codes say, or a bad control unit.

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2004 E500 4Matic 138,000 miles

I erased the codes and started the engine 4-5 times. On PIN 7 I have CODE 6 (Starter lock-out/backup lamp switch), on PIN 19 I have CODE 6 (Idle speed control faulty). The CE light is off.

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2004 E500 4Matic 138,000 miles

I've had a jumped timing chain that didn't have any popping noise on startup. It started rather normally, just wouldn't idle smoothly. Code 6 on pin 19 is just telling you you have a fault of pin 7, but it's beyond me how code 6 on pin 7 could be causing the symptoms. I suspect you just haven't had enough cycles for the CE light yet.

I will check compression to see if the chain jumped. Also will start it a few more times to get more codes if possible. Why do you think I don't have code 1 on pins 13 and 19 after erasing all codes?

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2004 E500 4Matic 138,000 miles

Pin 13 is speed signal - won't have any code or no code flashes. Pin 19 seems to take some cycles to reset. Nothing to worry about - codes should be gone if you're getting no flashes.

One way to check for chain problems is take off the lower oil pan and look for nylon bits of the upper chain guide. A timing chain jump is almost always (perhaps always) accompanied by a shattering of the upper chain guide (usually passenger side), the debris of which ends up in the oil pan in fairly short order. To me it's easier than taking off the value cover. But compression test is a good next step too.

One more thought - if you think it's one cylinder try pulling spark plug wires one at a time. Also with a stethoscope on each injector you can confirm that all are firing.