Why Does a Car Run Sluggish?

Common causes of vehicle sluggishness include transmission problems, failed oxygen sensors, hose leaks and damaged valves. CoastViews Magazine contributor Sherri Ingalsbe writes that sluggish vehicles experience reduced fuel efficiency and often exceed legal emissions requirements. Transmission problems are notoriously expensive, but many other causes of sluggishness only require replacement of inexpensive components.

Tom and Ray, hosts of the Car Talk radio show and advice column, explain that sluggishness is often a symptom of fuel-delivery problems. For example, improper fuel-injection patterns quickly hamper acceleration and produce sluggish responses at low speeds. This happens because the unbalanced injection pattern periodically floods the engine with excess fuel. This problem usually disappears at speeds above 30 MPH.

Chemical residue inside a car’s engine and hoses also make the car feel sluggish. This residue develops gradually as fuel, oil, coolant and other fluids circulate through the vehicle. The most effective way to dislodge and remove the residue is with a professional Motor Vac treatment. The Motor Vac shoots pressurized industrial solvents through all the hoses, chambers and tanks. This treatment is highly effective against sticky substances such as resins.

Although most sluggish vehicles have dirty engines or faulty fuel injectors, there are also other possible causes. The most serious and expensive is a faulty catalytic converter. Owners of older vehicles frequently choose to purchase another car rather than replacing this pricey part.