Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, my name is*****'m assuming that the engine tune was done properly and that the overall ignition system is in good order. If the car runs smooth off idle but shakes and runs rough at idle I'd have the fuel mixture checked and have the intake system checked for vacuum leaks. Rough running at idle is typically caused by incorrect fuel mixture or vacuum leaks at the manifold or around the injectors or by a fault with the fuel distributor or the injectors.
Let me know if you have any questions.
I can explain this much easier if we talk on the phone.
No problem on the phone call. That's entirely up to you but I can give you a whole lot more information in a phone conversation. I could write you a book on all of the things you need to check. If you want a starting point I would buy a can of carb spray and spray around the injectors and manifold with the engine idling and see if it affects the engine running. Vacuum leaks at the injector seals are a common problem. You can evaluate the mixture by pressing down 1 mm on the air flow sensor plate and see if it improves the engine idle. If the idle stalls try lifting up 1 mm on the plate to see if the rpm improves. If the engine running improves when you press down it tells you that the mixture is too lean. If it improves when you lift up it means that the mixture is too rich.
Let me know if you have any questions. Please remember to click on a rating for my service.