Do you sometimes feel as if your car has a mind of its own? You may have been sitting at a red traffic light, minding your own business, when suddenly the vehicle started to move ahead on its own volition. Thankfully, you were able to keep it in place by applying more pressure to the brake pedal with your foot, but you certainly want to get to the bottom of this strange affair as, after all, you're supposed to be in control. What could be causing this type of behaviour in your car?
In a vehicle fitted with automatic transmission, there is a perpetual connection between the engine and the wheels while the motor is running, unless you shift the lever into neutral. This is carefully regulated, of course, so that there is no urge to move forward when the vehicle is stationary and your foot is off the throttle pedal. Still, sometimes the car's brain may send an incorrect message to a critical sensor to increase the ignition at the wrong moment. In a conventional engine, this can also be caused by a faulty distributor or overly worn spark plugs.
You may also find that the fuel pressure regulator is playing up and pushing too much petrol into the engine when the vehicle is standing still. This could cause an excessive amount of fuel to be burned off and force the engine to turn more quickly than it should at that moment, in a scenario known as 'overrun.'
A faulty air pressure regulator could also cause an incorrect message to be sent by a vacuum leak sensor. This will confuse the vehicle's central computer, which will try to initiate forward motion based on this faulty data.
The problem may not be down to air pressure, fuel regulation or throttle sensors and may be associated with the alternator. If it is faulty then it may build up too much power, causing a surge through the electrical system and the urge to move forward.
Getting It Fixed
It can be difficult if not impossible for the average motorist to check for all of these issues, so it's best if you take the vehicle in to your mechanic as soon as you can. Just remember to keep some extra pressure on the brake pedal as needed while you're on your way. If you're really worried about the behaviour, park up and get the vehicle towed instead.
Learn more from a mechanic near you.