Does Weak Battery Affect Engine Performance. A weak battery cannot have a direct impact on the cars performance since the main work of a battery is to power up and start the engine. I agree with Manolito completely that a weak battery or cable end can cause poor engine performance.
But actually in extreme cases on older vehicles it can. Your cars computer needs a steady stream of voltage to work properly. A weak battery affects other parts of the car such as the alternator and more that are responsible for making the car perform efficiently.
Its amazing that your battery lasted this long.
Joined Dec 20 2005 Messages 14008. Great engine performance also leads to higher car fuel efficiency. So I doubt whether the battery is the culprit. A faulty electrical system in a car can play some very tricky games and your cars battery is part of that system.
