I own a 2002 c240 with 87,xxx kms. I am having problems diagnosing the rough idle. I have had the spark plugs changed, and now the IV Injector flush today. I filled up the tank with 94 octane and still seems to be running rough.
How long to I see any results from this, and what else should I have checked?

If anyone knows it would be greatly appreciated its driving me insane.

 

is the CEL light on??


have you hooked up an OBD2 reader to check for codes??

thats where you need to start

youll get it fixed once you know what it is

 

OBD2- +1 Find the source, fix it, done.

Here are some possible causes that may pertain to you, though. Mine idles rough, too.

Motor or tranny mounts, spark plug wires, gunk (techron takes helps care of it)...

 

No lights are on, Im pretty sure my mechanic hooked up the reader to find any codes. I also had them check the motor mounts said it was fine. Sounds like a misfire. Spark plugs and coils look great. When in idle feels almost like a diesel.

 

How long will the injector flush take to be noticed if it was the problem?

 

when you turn the key just before the engine starts dose the check engine light come on?? (makeing sure bulb is not dead/removed)

injector cleaner will take a tank or so to work

 

Assuming the OBD system is functioning, the car will alert you to a misfire.

 

the light comes on the before ignition, replaced plugs, checked coils, cleaned injectors, sort of check engine mounts. What else?

 

Check - Coilpacks, Plug wires - very possible, CPS, Vacuum system leak. Misfires require to reach a certain level before they trigger a CEL.

Make sure that MAF & throttle body are clean.

 

I had the coilpacks, plugs checked. I dont believe the vacuum system was checked. The throttle body was also cleaned. I had the injectors and throttle body cleaned. I am now waiting to see results. But I am still on the same tank of gas and it seems to be running worse and shaking more.

 

Its running awful, could be wrong but the heat is going on and off sometimes blowing cold when on hot?

 

I have a 2002 c240 elegance, 90km, had the spark plugs changed, coils check, throttle body cleaned, injectors cleaned. I had the injectors and throttle body cleaned a few days ago and still on the same tank of gas after flush but seems to be running a lot rougher, my mechanic said you will notice that until you are on to your next tank? And now I turned the heat and it came out cold then later hot??? Possible vacuum leak?

I really need some help no one seems to be able to diagnose this problem because the car is not throwing a code out. Please

 

You already have a thread on this, on the main page - HERE.

There is no reason whatsoever that you needed to post a duplicate thread. It's nigh on impossible to diagnose a car on a message forum, especially one that doesn't have a code. Why don't you try another mechanic that isn't clueless about the car? That's MY suggestion about the car. My suggestion about the forum is not to post multiple threads about the same thing as I'm pretty sure it is against the rules, and if it isn't, then it is certainly not good forum etiquette.

 

Good work matthew you are a true champion of etiquette. My advice to you is to get off this forum or your computer and try to get laid? Sound good? No f*** right off and ***?

 

next time drive it into the water! fa*

 

Ah, personal attacks - the big red flag of intellectual weakness. This was certainly not the way to get anyone to care about helping you.

 

+1
whats up with the noobs having attitudes here recently matt?

 

Threads merged. Same subject matter. No need for multiple threads. Nobody is that important.

 

my guess is its a vacum leak in one of the lines.

 

I bought a 2005 c240 not long ago. a week later it suddenly cut off when it dropped down into idle at a traffic light.Sometimes it sounded like an old V-8 duel exhaust sitting at a red light, or RPM's were all over the place, would shutter and cut off at slow speed or at stops, if it could idle it would idle high, had to sit with one foot on the brake and the other feathering the gas. Turning on the AC was enough to make it cut off (took me longer to find that out because I'm a windows down kind of person). I took it to a mechanic and they changed the MAF sensor and it ran well for a week or two. The back to same ole crud. I replaced the air filters and the fuel filter myself. Replaced the generic MAF the shop put on with a BOSCH, bought gas at different gas stations. Nothing changed. I was ready to drive it into the river and claim it as stolen, I was beyond over being the owner of a Mercedes. As last resort I must have tried every kind of fuel additive from the chain auto parts store. I figured it couldnt hurt, and made me feel like I was at least still trying. I ended up coming across a bottle of Mr. Gasket Cataclean. At $25 I wasn't sure if I was just letting myself be roped into another "miracle" fluid or if I should be sad that I've come to spending $25 dollars on a bottle of stuff that for all i know could just be big a big bottle of disappointment. Like when you open the bottle you actually hear the bottle say "sucker". You add this stuff when you have 4 gallons left, then drive around 15 miles, then fill back up. I had to drive a week before getting near 4 gallons but I finally got close enough and poured the bottle in. The next day... Runs like a dream (so far perfectly for 5 days - knock on wood) Idles silently at about 4-500 rpms - i keep checking to make sure its still on. No shake or shimmy. No problems at all. I'm completely shocked. Also completely mad that I was made a sucker out of by the mechanics and it was a plastic bottle of miracle fluid that actually fixed my car. Go try this stuff first - it is worth a shot.

 

Responding to someone's personal attack with one of your own. Now that is a true sign of intellect.

 

just say you don’t have a dam clue

 

You realize that was 13 years ago, and those people are long gone from this forum, right?
I'm like the last of the OG.