MBDaily

Hello to all. I am a newbie to the forum. Just sending out a first post.

I am currently pursuing a rough idle issue with my car. It can be fun (but expensive) at times to replace the old with new.
It's a 2007 C280 4matic. Bought it used at 113,000 miles last March and thought it rode well. A week later I had stored OBD codes. Previous owner long gone.
I had to pass emissions :l.
I fixed the codes with a new thermostat and 1 camshaft magnet. My friend installed the dreaded Intake manifold repair kit with HD actuator from Uro Parts.
I started to drive it more and noticed the car wasn't driving well. Stuttering and disengaging gears.
The rough idle was annoying at red lights too.
I wanted my friend to check out the drive condition while he plugged into the OBD2 port. We went out for a quick drive and after a u-turn and some acceleration, I popped the front right CV joint. The front wheel clocked 90 degrees and started smoking. I quickly pulled over on the shoulder. After waiting in the grassy median for over two hours for a tow truck we came back to a full parking lot. I had to beg someone to give me a spot so I can dump this disabled Mercedes. A few weeks later my friend replaced the CV joint and lower control arm. A couple weeks later he replaced the left lower control arm as well.
I had 4 new Michelin Crossclimate+ tires installed along with a lifetime alignment.
I installed new engine air filters and a Bosch MAF sensor. Then replaced my decimated spark plugs with 6 new double platinum Bosch plugs.
I got alerts for the left mirror signal, left front turn signal, left low beam, and left hi beam. All left, I'm not sure why, but I replaced in pairs.
I did an ATF flush with new filter and transmission connector. Engine coolant flush with new drain plug. Oil change with new filter and Liqui Moly pro-line engine flush. Installed new engine oil cooler gasket.
Replaced engine expansion plugs and PVC valve.
Last month replaced in-tank fuel filter (part of fuel sending unit). The old one had black fluid coming out and probably clogged.
Recently replaced front two engine mounts, but not the trans mount.
Bought liqui moly gear oil for differential fluid change next.
Not sure where to go with rough idle though. Maybe it's just part of this car.

chassis

Welcome! Please post a photo of the C280. Rough idle means fuel, spark or air is not right, or the ECU thinks they are not right. Usual culprits:

- air or vacuum leak
- faulty spark plug(s), coil(s) or wire(s)
- throttle position sensor
- MAF sensor
- crank sensor
- cam sensor
- bad injector(s)
- bad O2 sensor(s)
- breached cylinder head gasket - there is a battery of tests to rule this in or out

MJ50

moved to W203 forum...

MBDaily

I bought a cheap scanner tool. Shows I have a P1303 code. I will try swapping a plug and coil with another cylinder and see if the problem comes back.

konigstiger

Associated MBUSA bulletin releases, see attachments.

MBDaily

It's been a couple weeks after switching plugs and packs. After clearing the code, I have nothing showing up but still slight rough idle at stops.

I noticed on Bank 1 that the coil pack look older and the ignition boot was a different color. After reviewing online shops, the MB versions come with black ignition boots from Delphi, where as regular Delphi packs come with gray ignition boots.
Cylinder 1 had a gray boot and old looking coil pack. Cylinder 2 and 3 had black boots with a newer looking coil pack.
Cylinder 1 looked different than 2 and 3, yet Cylinder 3 had the code.

MBDaily

Misfire code went away after using 2 cans of BG 44k Platinum fuel cleaner.
Replaced accessory drive belt, belt tensioner, and two idler pulleys. Rough idle was reduced some. Almost there.
Noticed leaking front left CV axle and trashed transmission mount. Both parts on order. Will report back findings.