QuestionThis problem only happens after the car ahs been driven for about 1/2 hour. The car will not accelerate or maintain a speed up hill. Depressing the gas pedal has no affect until the transmission down shifts and the car will surge forward. When a higher speed is reached and the rpms lower, the car is still not responsive to the gas pedal. When I stop and let the sit for ten or so minutes, it operates normally for a while. What can I do other than paying a mechanic for drive my car for an hour? The car has all the recommended service and has 110,000 miles.
AnswerConfused by wording:
Is the engine trying to raise RPM before down shift?
When it down shifts, does it have power, or is it weak?
Sounds like classic plugged catalytic converter symptoms.
The other options are:
Possible:
#1. Fuel filter plugged.
#2. Fuel pump relay heating up and failing.
#3. Ignition coil heating up and failing.
#3. Fuel pump failing.
#4. Bad ignition control module.
This is all blind guess without further hands on diagnosis.
Start with a new fuel filter, it is possible that even a new filter can fail from a bad tank of fuel.
A Mercedes only independent garage or dealer should have your diagnosis in a couple of hours.
If it is not #1, take it to your local MB dealer for diagnosis, it will save you money.
