'09 C300 Engine Shuddering/Hesitation
 

Good Morning all,

Just found this forum after researching heavily into why my 2009 C300 (V6 3.0L) has been shuddering/hesitating from idle to 3/4 throttle. I haven't wanted to take it flat out and break something... This happens at very random intervals and I can't seem to find a happy zone. I'm not getting any lights on the dash like a CEL... The first time this happened was immediately after a Service A at my last local dealership. I took it back to them and the manager put the air cleaners back on and it seemed to work fine. I drove it across country and it was fine until the last 20 miles of the journey. Then it stopped about 2 days later... That was back in June and now in November, it started again last Thursday when I didn't have enough time to let the engine warm up before driving it.
Is it the MAF? Fuel issue? Any help would be appreciated. I'm looking for a DIY fix if possible.

Thanks!

Nate

How many miles are on it? If it's higher up in mileage, have you checked/replaced the spark plugs? Also check to make sure the air filter housing is seated/fastened properly

It has 85,xxx miles on it and I'm doing the Service B on Thursday. Does the air filter housing have any screws or fasteners on it? The last time I had this problem, the housing wasn't seated properly and a readjustment seemed to have fixed this... But it hasn't been touched since June

It doesn't have any screws or anything to actually fix it to the engine, it's held down by a clamp at the rear and slots into a couple of holders at the front. It should be completely flush with the ECU in the middle. I would check your spark plugs also, that may be around the time they need replacing although I've heard people going up to 100k miles I think

Checked the plugs, need to replace them. I have the plugs on order to pick up today. Is there any adverse reactions from driving an extra day on bad plugs? I'm hoping I can at least get them changed tonight.

Also, is there anything that a Mercedes spark plug job might need? Aside from the T30 (I'm assuming that's the size) for the solenoid, a 5/8" ratchet + extension, and a torque wrench?

Should be fine to run another day. Heck, it doesn't even sound like you have a rough idle so that's better than most people with spark plug issues.

Symptoms remind me of a vacuum leak (not properly fitted air cleaner, etc). Although I did have intermittent similar symptoms when I had a bad MAF (on a w140 though).

As far as spark plugs go, very simple and basic procedure, like almost all cars. Just torque things to spec.