By December 7, 2006 0 Comments Read More →

Mercedes Dies and Runs Rough

My Mercedes 320 SL is stalling and inconsistent, rough idle quality, poor throttle response, reduced fuel mileage and hesitation during acceleration. When it starts-up it’s fine for about 3 miles or if I don’t hit the gas to hard. When the car is running for over 10 minutes the problem gets worse and then dies, wont go or like a back fire. I don’ know what to do, if I had the money I would get it fixed however times are different being a single parent. I can only assume 2 problems and both are hard to pay for all at one time. Which one would you recommend or advise for me.

1) air mass sensor

2) air mass meter sensor

Please Help

Hey Clint,

How are ya man? I am not much of a Mercedes mechanic and they are very much different from Japanese and US vehicles. It really sounds like you have a lack of fuel control or lack of fuel pressure. I would want to test the fuel pump pressure before I did anything else. Fuel pumps tend to fail most when they get hot, like what you are experiencing. Lack of power, hesitation, dying are all common lack of fuel complaints. Back firing can be caused by an engine that is running lean ..lean meaning, lack of fuel. The fuel system on a this car is complex, so I would not just run out and replace the fuel pump. There are relays and regulators .etc. etc. etc. good ole German OVER engineering.

Before I guessed at anything I would pony up a diagnostic fee at the dealership or some place that is experienced with Mercedes. Most general repair shops are probably NOT experienced enough for this type of complaint. In some cases you could end up spending MORE money with the wrong repair shop and wrong diagnosis than if you just went to the dealership in the first place.


Austin Davis

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Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."