I have been searching the forums looking for an answer to a problem I am having with my 2001 C240 but cant seem to find a good answer. It has ~150K miles on it. First, I am not getting a CEL. The problem only seems to occur when I start the car first thing in the morning or after it sits for a few hours. When I give the car some throttle it takes off like normal. After a little driving the car starts to choke its self/loose power. With the same pressure on the pedal the car just slows down. Ill take my foot off the throttle for just a sec and then when I get back into the throttle the car takes off again like normal. It might do this a couple of times a minute or maybe once every 3 or 4 minutes just for a few seconds each time. This happens whether I am going 5, 15, or 55mph. After driving the car for 15 minutes or so the problem seems to go away. Any suggestions?

 

Next time when you are experiencing the problem, disconnect the electrical connector to MAF and see if the problem goes away. You may get an error on the cluster when you remove the connection to MAF. It will go away when you plug the MAF back in.

 

sounds like you are either not getting enough air flow or not enough fuel flow(i.e. old fuel filter). check what pcy suggested and see what happens, could be a bad MAF.

 

Yeah the MAF could be the culprit. It might just be on it's way out.

 

only thing that makes me doubt the MAF is that i think the CEL should come on if this is bad, shouldn't it?

 

Have you tried resetting it? Dont know the extremity of it but I know my car drove smoother after resetting

 

Idle Air Temp sensor is part of MAF. So, if that part of the sensor is acting up, you can see the symptoms OP mentioned.

MAF is an interesting part. In every time I've had issues with MAF on my ML as well as C320, there was no CEL.

That is why, I was suggesting OP to disconnect MAF (not to go ahead and replace) to confirm my suspicion.

 

It's either airflow or fuelpump, I don't think there are any other possible explanations for choking and powerloss..

 

I had a similar issue with weak running at cold start on my 2001 C240, at about 122000 miles. Eventually the engine would not run over 3000 rpm. Turned out to be the MAF (mass air flow sensor) was failed. The OEM part is pretty easy to replace. I bought one from Autohausaz.com. After I put the new MAF in, I started getting CEL codes for lean mixture. After some debugging I found that the rubber donut between the MAF and the manifold had shrunk so much it was leaking extra air into the manifold. The top gasket was pretty loose as well, so I bought both (under $10 each) and all has been well since. I did have to pull the battery cable to clear the engine computer memory before it stopped correcting for the old (failed) MAF.

 

MAF, lack of fuel pressure (filter or pressure regulator in filter), fuel pump, CPS, TPS, stumble due to O2 sensors cycling too slowly, vacuum leaks.

Please get hold of an OBDII scanner & check for stored codes. Autozone will loan you one. Plug under rectangular flap under the steering column.

Post the codes & let us have a look.

 

Or do as what Glyn said, don't guess, but check the codes.