Hello crossfire family, My 05 Auto limited roadster has recently been having quite the rough idle (extremely aggressive like whole body shaking) at stop lights, however the second i hit the gas she's smooth as butter.
right over 100k miles, not showing any codes other then brakes. Have looked for vacuum leaks visually (still need to do a smoke test), checked air filters which were almost perfect. Plan on checking spark plugs, maf and icv later today.

From what ive gathered browsing forums these seem to be the most common of the issues, As I know this is quite a common problem any tips of advice would be much appreciated.

• Vacuum Leaks – Cracked hoses, intake manifold leaks, or PCV system issues.
• Dirty Throttle Body – Carbon buildup causing improper airflow at idle.
• Failing Idle Control Valve (ICV) – Sticking or dirty ICV affecting idle stability.
• Dirty or Failing MAF Sensor – Incorrect air-fuel mixture causing idle issues.
• Bad Spark Plugs or Ignition Coils – Weak spark can cause rough idle but smooth driving at higher RPMs.

 

At 100K, replacing plugs and wires a must, possibly coil packs and the MAF is pretty much normal.

 

It's long since time for plugs and wires, however, if the ECU does not recognize any misfires, you might try a vacuum leak test:

Start engine.
Raise hood.
Observe how "shaky" the engine is.
Yank oil filler cap off.
............... Did the engine get even more "shaky"? If so: Vacuum leak! (FIX IT.)
............... Did the engine get even more "shaky"? If not: You have no vacuum leak. (Keep looking for some other cause.)

 

I was on the Benz forum a while ago and remembered this thread: LINK to Benz Forum thread rough idle
One member suggested this to test it, (second post down in the thread): When the engine is cold and off, take the serpentine belt off. Check the pulleys, especially the idler and tensioner.
Then while the belt is off run the car for a minute and see if it still idles rough. Do not let it warm up. (This is up to you if you want to try it).
He also mentions that there was a recall for some US harmonic balancers. He didn't give what years this happened.
It's worth checking out the thread, though.

Another thought is a clogged catalytic converter.

 

Thank you very much, exactly what I was looking for, somehow had missed a crankcase breather hose that had came apart at the seal. Id imagine that could definetly be the cause. Definitely the easiest thing to do out of all the options so I'm hoping I'm in luck and can just replace it. Thanks again boss man
Brady

 

Hopefully that's it.
Best of luck to you,
John