mbenz1

I didn't get any replies over at the 550 forum, so I am posting here to see if anyone has any idea.

OK, so last Sunday I went to start the car after parking at the mall for 2 hrs. and it would crank and crank but wouldn't start. 5 mins later I gave it another try and it fired right up. So, I thought to myself it must be the Crank Shaft Position Sensor as my car has 48,000 miles on it and has never been changed. I took it to my mechanic and he thought it was the CPS also, so I had he changed it out on Thursday. Everything was fine until today it did the same thing!!! This time though the crank didn't sound as strong as the first time it happened. So, I waited a few minutes and gave it another try and it fired right up! BTW, I already took it to a battery specialty place and they checked my battery and they said it's still very strong. What could it be then if it's not the CPS??? Anyone had the same problem before? Any input is very much appreciated.

StarvingArtist

Check your fuel pump connector under the back seat. Does it look burnt inside? I think it's on the drivers side.

mbenz1

This might be a stupid question but how do you get to under the back seat? I don't see any openings for access, may be I am just looking at the wrong place.

StarvingArtist

There is a hole in the carpet right at the bottom edge of the seat cushion. Put your finger in and push the spring clip while pulling up on the edge of the seat. The other clip toward the center console just pulls straight out, (hard). You'll see.

mbenz1

Thanks. I took it to a new shop today and he thinks is the coding on the car that is causing the problem. I will report back on Friday after he plugs it into the computer.

C3Duece

If the car doesn't have an aftermarket tune the coding is not the problem. The fact your "mech" thinks it is makes me question his competence.

StarvingArtist

Also check the fuel pump relay connection for overheating. Computers can be useful, but when it comes right down to it, you need fuel, spark, and compression to light a fire in it-----just like 100 years ago.

mbenz1

So, the tech thinks it could be the battery as I have never changed that out ever since I bought the car, so it has been 7.5 yrs and he also tested the voltage and said it was a little low. New battery in and tonight it happened again.... I tried taking the rear seat out but got stuck after popping the clip close to the door. So, to release the side close to the center I just yank it out? It seems pretty tight and I don't want to break anything.....

StarvingArtist

It won't break. Put a tiny smear of grease on it to make it easier next time.


Pull it straight up, you can bend it if you pull it out crooked enough, no big deal, bend it back.

mbenz1

Is it the one on the right with a white sticker? I was able to pull that one out only and it looks fine to me.

mbenz1

Just spent over an hour with my tech and he checked to see if there were any fault codes and only found some random codes that he thought had nothing to do with my problem. I remember for the past few months the car would tell me a few "Key batteries low" and even though I changed them out to new ones it would still tell me that once in a while. Once in a blue moon it wouldn't detect the key, so now I am keeping my fingers crossed that it is the key that's giving me the problem. This is my second day using the new key so hopefully the problem won't come back.

StarvingArtist

No, it's usually burnt on the other side. (under the other seat)
Hopefully just the key.

mbenz1

It happened again!!!! I am beyond frustrated right now. Well, no choice but to take it in to the dealer in the next few weeks and hopefully it will happen at that time. I was there earlier and talked to a tech and he told me there's problem with the ME on the CLS? He was busy so didn't get into details about what model years are having the problem. I am now keeping my fingers crossed that it's the ME as the warranty is 8 years and I am only 2 months away from that!!!

StarvingArtist

Bummer, I would still check your other pump and relay before handing it over.

mbenz1

Well, I changed out the fuel pump relay myself right after the CPS and I got it from the dealer, so that one should be good. I am wondering if the CPS from the dealer could be defective. I asked my tech about that but he said if it's any of the 2 then I would get fault codes but I got only random ones like "Chip Card Faulty" and he said that's the first time he has seen that one.

StarvingArtist

Maybe the 550 motor has a cam position sensor, just guessing.

mbenz1

I have no idea. I am kinda busy these days so won't be able to take it in until later. I will report back once they find out what exactly is causing the problem.

StarvingArtist

Wasabiz55

I've been having a similar issue with my cls55, it randomly has a long crank/start but it eventually turns over. I'm still unsure what is causing this, but I'll be checking with the dealer tech tomorrow. Have you noticed any fuel smell coming from the back (outside of the car) after shutting down?

taleb659

I just had the same exact problem on my w211 E55 and it ended up being the camshaft position sensor. Very easy to replace and the problem is now gone!

mbenz1

No fuel smell after shutting down. So, did your dealer find out what is doing it? I just took mine in few hours ago, waiting for a call from them.

mbenz1

Did you mean the crankshaft position sensor? That's the first thing I changed then I changed the fuel pump relay also.

taleb659

No not the crankshaft sensor, I changed the camshaft position sensor. They are two different sensors.

taleb659

This is the part number for the camshaft sensor on the 550 motor: A2729050043

mbenz1

Thanks, but did your car throw a code when the sensor was having problem? My car has been at the dealer for 2 days now and they still don't know what is causing it....