My car have stopped running while I am on the road. The first time it happened was I was going out of a parking lot and it just stopped. Cars behind me were honking their horns. I restarted it and thankfully it worked. It happened again two days later - same thing - the engine cut off. And in the morning i have to really warm it up for an extra 3 minutes, otherwise, when i put it on DRIVE, the engine shuts off. The gas tank is full. Can you please tell me what could be wrong with my vehicle? Thank you very much.
My car's engine would just stop running. My car 156,000 miles. on 1992 Mercedes-Benz 190E
by Visitor in Chesapeake, VA on November 01, 2010
ANSWER by patrick mannion on November 01, 2010
We would need to drive the car to experience the problem first hand and do some basic diagnostic tests before guessing. An engine needs three things to run, mechanical integrity (which it must have or it would not restart), fuel and spark. To find an intermittent problem like this I "tee into" the fuel line and tape a fuel pressure gauge to the windscreen so I can monitor fuel pressure when the problem occurs, if fuel pressure falls off, or drops to zero you know your problem is fuel related, you then start tracing the fuel pump, fuel pump relay and sensors that allow for fuel pump operation. I also drive around with a timing light attached to one of the spark plug wires, when the vehicle falters I pull the trigger on the timing light and see if I have spark. If the there is no spark I check the ignition system, wiring and sensors associated with the ignition system. Intermittent problems are hard to find and your vehicle has limited diagnostic capabilities. If the engine has computerized engine idle control, the computer in your car constantly monitors the speed of the engine and tries to maintain an idle speed based on engine temperature, and "load" on the engine, if the computer senses the idle speed is too low it automatically raises the engine speed to prevent the engine from stalling but it can only compensate so much! A problem in the idle speed control system can obviously be a cause for an engine to stall and cut out. Understanding how each system works, having a good wiring diagram and volt/ohm meter and patience are required to trouble shoot this kind of problem.