Hello, I recently bought a 2005 c230 kompressor. The car is a manual sedan, with 95k miles. The other day, I was accelerating(bout 50% throttle in 3rd), and my car suddenly bogged down really bad, and started to knock roughly, and the check engine light came on. I called the dealer, they told me a number of things, but they said it didn't seem major, maybe bad gas or condensation in the tank. They told me to run it up to autozone and get some fuel additive, or octane boost, so I did. It was a small bottle of injector/cylinder cleaner, so I dumped it in the gas tank. 10 miles down the road, car suddenly smooths out, and the check engine light goes off.

Cased closed, right? Just a clogged injector or something? Nope. It came back today, check engine light, bog, and knocking.

Additional notes-
-Problem seems intermittent, and semi linked to accelerating. Usually if I restart the car and baby it the problem isn't noticed, but if I give it a little gas, it comes right back.
-Restarting the car temporarily fixes the problem
-I am still on the same tank of gas, haven't refueled since I put the additive in.

I'm not really sure, but I think the injector in one of the cylinders is getting clogged somehow, maybe a bad fuel filter?
This car is new to me, so I don't know everything yet, any help or suggestion is greatly appreciated.

 

Put some seafoam in the tank today, as it is a little bit more aggressive, while still being oil based. Check engine light is off, and car is running smooth. Hopefully it stays that way.

 

These cars seem sensitive to varnish build up from using low octane fuel. Use a good fuel injector cleaner, then use a premium fuel 93 octane with cleaner additives.

What code is being displayed? Most autoparts stores will read the codes for you for free. My guess would be it is for an engine misfire.

When your engine detects an engine misfire it shuts off spark to that cylinder to prevent damage. Thus, you are running on one or more fewer cylinders causing it to be boggy. If you turn the ignition off and the back on it will rest and allow you to run on all cylinders again until it detects another misfire.

The misfire is being generated by valves hanging up due due to the varnish build up. It may take several tanks of cleaner to get the engine cleaned up.

No promises that this is the problem, but it is common.