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I own a 2011 Mercedes Benz E250 CGI W212 Coupe (4 cyl gasoline turbo) with 26,000 genuine miles. I have owned the car since new. The car is serviced every 12 months by the Mercedes Benz dealership the car was purchased from. Up until now I have had zero problems, the car has been super reliable. However for the last two months, every morning, after the car has been sitting overnight in the undercover car port, the car starts well but when I start driving for the first 60 seconds, the acceleration hesitates as though the engine is starved of fuel. This also happens in reverse gear. After 60 seconds the problem goes away and the car drives well for the rest of the day with no further issues. There are no error messages on the dash board and the code scanner shows no error codes. I took the car to my local Mercedes Benz dealer and they replaced the ignition coils but the problem returned. I then took the car to a local independent Mercedes Benz specialist mechanic and he replaced the park plugs which had lots of carbon build up, but the problem returned. Both mechanics kept the car for three days. Has anyone else had this issue and resolved the problem? Thanks.
 

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So it hesitates the whole 60 sec or it just does it for a moment within that 60 sec? Either way I think I'd get an OBD2 dongle to use with a phone app and trend the intake temp, water temp, fuel pressure, manifold pressure and see what it says. Other things to check with the app would be things like O2 sensors, cam and crank position sensors and throttle position, maybe throttle command too. Fuel flow, fuel pressure, air/fuel ratio. Lots of stuff to look at and it should give you a clue.
I'm doing something similar with my car now but the data flow rate is slow so it's frustrating. So if yours is just for a moment, keep trying each day to better your odds. If it's steady then hopefully it'll tell you right away. I've been using the Torque Pro app with the Realtime Charts plugin. I bought a super cheapie $11 dongle (amazon.com/dp/B00PJPHEBO), and the apps were ~$7.50 altogether, so pretty cheap for the info you get out of it. I can then view the chart on my phone later, and can export the raw data to excel and create a chart in excel from that. The delay issue for me is the data for different things come at different times. For example it will say my ign timing is 30 degrees while at 16 lbs boost, which is not possible. So on avg it's right, but anything within a second is very questionable. So in my case with the ign timing to boost I just have to mentally move the data over a bit to match, which I'm estimating but it's better than nothing. Also, the more data you're requesting the worse it gets, so if you narrow it down to something I'd delete the items that don't apply.
 

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So it hesitates the whole 60 sec or it just does it for a moment within that 60 sec? Either way I think I'd get an OBD2 dongle to use with a phone app and trend the intake temp, water temp, fuel pressure, manifold pressure and see what it says. Other things to check with the app would be things like O2 sensors, cam and crank position sensors and throttle position, maybe throttle command too. Fuel flow, fuel pressure, air/fuel ratio. Lots of stuff to look at and it should give you a clue.
I'm doing something similar with my car now but the data flow rate is slow so it's frustrating. So if yours is just for a moment, keep trying each day to better your odds. If it's steady then hopefully it'll tell you right away. I've been using the Torque Pro app with the Realtime Charts plugin. I bought a super cheapie $11 dongle (amazon.com/dp/B00PJPHEBO), and the apps were ~$7.50 altogether, so pretty cheap for the info you get out of it. I can then view the chart on my phone later, and can export the raw data to excel and create a chart in excel from that. The delay issue for me is the data for different things come at different times. For example it will say my ign timing is 30 degrees while at 16 lbs boost, which is not possible. So on avg it's right, but anything within a second is very questionable. So in my case with the ign timing to boost I just have to mentally move the data over a bit to match, which I'm estimating but it's better than nothing. Also, the more data you're requesting the worse it gets, so if you narrow it down to something I'd delete the items that don't apply.
Thank you Chevota, I appreciate you taking the time to provide such a comprehensive reply. It was very useful. The problem resolves itself withing 60 seconds, sometimes it resolves in 30 seconds. I will but the device you suggested and will start accumulating data.I have noticed the car must remain un-driven for at least 20 hours or the problem does not occur. Thanks again for your good advice.
 

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Just to close the loop on this one, we suspected dirty fuel, so ran the tank down, refilled it, added a fuel system cleaner and drove the car until the fuel ran down and refilled it again. It appears to have cleared the problem.
 

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So you're saying this entire issue all took place on one tank of gas? And it must've been a pretty old tank of gas too.
Interesting.... Usually I only see bad gas in things that don't get use for many months on end, like seasonal vehicles or something that breaks down and you don't fix it for a couple years.
Well, I hope that's all it was, and I guess you need some Sta-Bil?
 
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