I recently purchased a CL55 and it runs rough at idle after 15 minutes of driving. The dealer that sold me the car said on paper he would fix the check engine light on his dime, and that it was a secondary air pump issue. The IAT sensor had its tabs broken off and actually blew out under boost. I was not told about this and basically broke down on the side of the road until I figured it out. I replaced the IAT today and the car drove good for 30 minutes then the rough idle returned.

I have went through the car and found several boost/vacuum leaks such as a loose pcv hose as well as the main coupler from the air box that was not fully secured. I have went through and zip tied everything that I can access under the air boxes and other plastic covers.

I have been pulling and clearing codes on a daily basis. Depending on the day I get different codes. I work closely with Mercedes of Seattle on a daily basis and already had a tranny service as well as vehicle inspection done.

po422 & po432 main cat efficiency codes
po410 secondary air pump

po505 idle air control system
po455 evap leak detected
po221 pedal position sensor
po106 map sensor

(I can put up all the actual codes from the Mercedes scan tool, but these are more descriptive)

Note that all these codes do not come back at the same time, and please excuse the brief code description. From what the guys at Mercedes have told me the first set of codes are related to the air pump issue and the second set all sound like there is a vacuum leak some where. The dealer's mechanic did the valve cover gaskets and did shotty work. The air box to throttle body coupler was not pushed on all the way. When I found this I thought for sure I fixed the problem but I was wrong. I'm getting very frustrated. Below is a link to my website just to give you an idea of the cars that I know. My car is the green one and makes around 700 hp. I built the short block and tuned this car so I am not a rookie when it comes to cars, but I need some help with the CL.

http://groundvisionperformance.com

Any help would be very much appreciated. I have access to Mercedes scan tools. Are there adaptions I need to set? Battery disconnect?

Is the map sensor for these cars on the front of the engine behind 3 coolant lines near the passenger side head? I have tried to find it on ALLDATA, but the pictures are horrible.

 

I finally found an E55 thread that had similar problems and everything is pointing to a map sensor. Going to pick one up on Monday. From the looks of it I should just be able to pull the air box on the passenger side to access it.

It looks pretty straight forward, but any tips would be appreciated.

p.s. The map sensor on these cars is on the Y-pipe near the IAT sensor.

 

All codes have freeze data attached to them. Review and see what parameters were out of whack and tripped the code. This should give you clues.

You can reset adaptations, but this is not your problem. I would relearn the tps. There is a special procedure for that in sds.

My vote goes for either dirty throttle body or vacuum leak. Get yourself a $5 set of mechanics stethoscope and listen under the hood. The 55 motors are vocal and very clickety- clacky, but a vacuum leak is unmistakable sounding.

Freeze data will provide clues.

Let us know

 

I have already tried a stethoscope and couldn't hear anything. I think these motors are relatively quiet compared to what I'm used to. There is no noticeable hissing from any where. With a Diamond Star you can pressurize the whole system and pin point your leak from sound or by spraying soapy water. The map sensor code is the one that steadily comes back. On the dealer scan there was also two mentions of map sensor faults that did not appear as standard OBD codes. Here are the codes Mercedes pulled that I believe are related to the MAP.

P2007-008 B28 (Pressure Sensor) Signal Implausible

P20D4 The load limit is active. (P1999)

Here are the other ones.

P207E-001 Left Cat is insufficient (P0432)
P200B-001 Right Cat is insufficient (P0422)
P202B-002 Idle speed control is implausible: Short circuit to ground or open circuit
P20A2 Idle speed control is implausible: Check system for unmetered air
P2003 Malfunction of secondary air injection(P0410)

My access to Mercedes tool is limited. I work for a broker and work with their service department quite a bit but rarely have access to actually talk to a tech. I plan on pulling off the air box coupler from the throttle body Monday and going from there. We actually have a 5,000 dollar scan tool but it is no Star machine.

Any tips on getting it off or do I just need to pull of the passenger side air box? The place I work for is also a shop for European cars but the guys are not too familiar with the supercharged engines so I think I will be on my own on this one.

Thanks for the reply by the way. I appreciate it.



EDIT
Found this thread just now.
https://mbworld.org/forums/w211-amg/...-inside-3.html

How many bars will these MAP sensors read? I have a 4 bar Omni Power MAP on my Talon.

 

I pulled the MAP sensor out and am waiting on my new one to get here. Ill post results tomorrow.

Where are all the people that work on their own cars on this forum????

 

Replaced the map and still have the same problem. I notice the throttle body is making some loud clicking noises though when its idling rough. I wonder if the ISC as failed.

 

i have not heard any noises from the tb at idle...

maybe remove and inspect? they do get dirty and maybe that is enough for something to not get seated properly and the step motor to skip/ click...

as i said - there is a tb learning procedure in sds. if tb is bad it might fail the procedure and that will be your clue.

one more thought- what codes are getting logged now? i assume- the same ones... ?

the po221 (pedal position sensor) is also an interesting one. maybe have the pedal rheostat tested? (i do not know how)

lastly- did you fix the air pump?

i would fix what i can to minimize noise before going after the idle problem

on people working on their own cars- there are very few and far apart. those cars (as you have noticed by now) are not trivial to work on. the dealer with all their training is often as confused as we are about a problem. if you want to work on your own car buying an sds ($350 chinese knock off) is an absolute must.

 

The ISC stepper motor is definitely making a noise. I have an appointment with the dealer tomorrow to have it diagnosed on the dealers dime I bought the car from. They will also be inspecting the air pump. I looked at it and cleaned connections but didn't see anything out of order. I still have not made sure it runs in the morning yet. I've been too worried about the rough idle.

The car threw another map sensor code as well as the idle control codes. At least I have a new IAT and MAP sensor. I also learned a little more about the car. When I took the throttle body off the car it was very clean. I cleaned it up and it really looks like new.

I did notice there was a flap/valve right inside of the supercharger that lead down to the intercooler. Is this supposed to be open when the car is not running? Mine was.

Thanks for your input on my situation. I really appreciate it.



Something like this?
http://www.ebay.com/itm/Mercedes-STA..._Video&vxp=mtr

 

So after all my trouble of changing sensors and what not it turned out the Mercedes dealer found a vacuum leak from the purge valve. They did not tell me exactly which hose was loose but it fixed the problem. I spent hours and hours looking over this car zip tying all of the lines and had the throttle body off and did not see anything that was off.

They charged $140 to trouble shoot and another $140 to take the air box off and plug the hose back in. The dealer I bought the car from paid the cost with no questions asked and now it runs great.

 

Good to know

 

A little more info on this. The purge valve is very obvious on the driver side fender well and the hose runs to a stainless line. This is very straight forward and this is where I got lost when the dealer told me there was a leak there. I had the rubber line zip tied and clamped.

BUT

The place to where the stainless line runs on the back of the motor came out. Common problem when people do valve cover gaskets. I still haven't had it apart again to see exactly where the line goes but this is good to know. Made me feel like an idiot that I couldn't find it.

 

Very glad to here you got the engine running well !!!
Thanks for the description regarding the vacuum leak, I'm sure it will help someone in the future !!!!

 

Many years later... I just got that problem and i will be solving it soon with the main thought that its the same problem as you i have many of the same codes coming up. Thank you for your detailed write up and solution.

 

Follow the hose from the purge valve to the back of the manifold. It is really hard to see, but with a mirror and laying on the top of the engine you can see it.

 

Huge thank you! I did the spark plugs and valve cover gaskets this past weekend and after putting everything back together on the CL55 I started it up and things sounded fine. After revving it a bit the idle wouldn't drop below 1500, and when driving the car wouldn't downshift to first when coming to a stop (it would putter a bit almost like stalling out). Read this thread and that hard purge valve line connected to the SC intake was exactly the issue (it had been accidentally disconnnected).

Very difficult to access, had to remove the breather hoses and air boxes and still was extremely difficult to view however patience and persistence got things connected (about 7 inches into the rear of the motor). Thanks everyone for chiming in, took it on a road trip and the cars running phenomenal now!