Got back my dad's old C280 that I had bought from him and given to my daughter a few years ago. It did not get the careful maintenance living with a 20-something that it did when my father was the owner, and I need to get it squared away again before it goes to my son. It's got just over 250k on it.
Codes are P1700, P0400, P0300, P0301, 0302, 0304
I have done quite a bit of research on the vacuum leak code and replaced the vacuum controller on the passenger side engine bay, which at least stopped the hissing. However there is a light green line that is connected to what appears to be a solenoid of some kind and runs past the oil filter on the drivers side, where it is hanging loose. I cannot find a port or nipple for it to attach to. Any help? The vacuum line diagram I have in my manual is vague on this.
As for the misfire codes, I replaced all six plugs, cleaned the MAF and snaked the metal tube on the back of the EGR valve, to no avail. It stumbles and hunts at idle, is slow to accelerate but once over 3000rpm picks up and runs fine. Second and third shifts are rough as well. I have not tested the EGR with a vacuum tester but I believe it is the original one.

Any advice you folks might offer would be appreciated. This was and should be a really fine running car, in fact up until last summer it ran like a champ. Cosmetics are decent, though it needs a new headliner and some cleaning up, and the drivers window doesn't work either with the switch or the key-in-door so eventually I need to get to the window motor but getting it running right is the priority.
Thanks.

 

Bump, anyone?

 

Are these codes appears again..?

ZAYED,,

 

The codes haven't gone away.
I need help identifying where the green vacuum line is connected on the intake side.
I am trying to figure out what is causing the rough idle.

 

I see,

is your Engine M104..?

ZAYED,,

 

This dark green vacuum line is what I am referring to. Here it is above the passenger wheel well;

Here is the other end, from what I have read on other threads this often get pulled loose by ham-handed mechanics when trying to pull the oil filter.


Where does it connect?

 

Assuming this line goes to the gearbox vacuum box(attached to the right side of gearbox)..!

ZAYED,,

 

Awesome! Now I just have to find that, do you know if it is accessible from above or below the car? I have done everything short of removing the intake manifold itself and cannot see the port where this attaches, so I assume I have to get beneath the car.

 

Bear with me, where would I find this information?

 

Before goes under the car, is there a vacuum attached to throttle body..?

ZAYED,,

 

Every MB should has an Engine code # started with (M):-

http://en.wikipedia.org/wiki/List_of...s-Benz_engines

http://en.wikipedia.org/wiki/Mercedes-Benz_M104_engine

*when you put your VIN # in Mercedes EPC or VIN decoder, Engine code should appears as well..

ZAYED,,

 

Yes, there is a white (you can see it in the picture passing beneath the intake) vacuum line that goes to the throttle body, that is still connected.

 

That's good,

about rough idle, many things could cause that:-

"hot film in MAF goes bad/coils/spark plug/spark plug wires/fuel filter/bad or dirty injectors"

did you replace any of these recently..??

ZAYED,,

 

Also,

don't forget "CPS" sensor, it's one of the most common guy, that causes big failure & misfiring in whole ignition system..!!

ZAYED,,

 

I just replaced the CPS in my Jeep, but in that case the car was completely dead, no start or running. Didn't think it would be a culprit if the car runs.

 

I replaced the plugs and cleaned the MAF, I have been holding off replacing the coils and wires until I eliminated the easy possibilities. I suppose pulling the fuel rail and injectors would be next.
By chance do you have the resistance figures for testing the coil packs?

 

In some cases; it cause bad emissions/poor idle/randomly ignition signal to the ECU directly,,

*it could be not from it, but it's one of important guy to consider with MAF...!

ZAYED,,

 

Occasionally; when hot film in the MAF goes bad, clean it will NOT cure it,,

don't have the Exact coil resistant, i test them with multimeter with (200 ohms) by the coil banks,,

i think you have 3 coils isn't..?

ZAYED,,

 

Correct, three coils, one for each pair of cylinders although I don't remember which ones are linked.