What Can Cause A Misfire?
February 6th, 2017
One day, you go to start your vehicle and you notice it struggles a little to get started…then it runs a little rough. You experience lumpy idling and a faltering, bucking sensation while you accelerate with the Check Engine light on the dashboard illuminated. Why does this happen, seemingly out of nowhere?
There are many reasons why a vehicle might start running rough, but let’s consider a few basic ones right off the top. Consider that any internal combustion engine needs fuel, air, and spark to run. In the end, a rough running or misfire condition is going to come back to one of those three factors, so we can start a process of elimination:
Clogged air filter: an air filter that’s really dirty and clogged will obstruct airflow into the fuel system enough to halfway smother the engine and cause a misfire.
Clogged fuel injector: this is a problem that doesn’t happen often, but it doesn’t mean it’s completely unheard of, either. Along with a clogged injector, low fuel pressure in the injection system or a problem with a fuel rail can cause a misfire.
Vacuum leak: the engine’s controls rely on multiple vacuum connections as well as vacuum canisters, amplifiers, reservoirs and junctions for vacuum lines. A vacuum leak can be enough to cause a misfire and even log a trouble code in the engine computer.
Spark plug: while spark plugs only need to be changed at about the 75-100,000 mile mark these days, that doesn’t mean they *never* need to be changed. A worn set of plugs can cause a misfire.
Ignition: in the old days, running through a puddle could be enough to cause moisture or condensation to collect inside the distributor cap. Vehicles no longer use distributors and plug wires; most instead use a coil-on-plug setup to deliver spark right at the plug. These “coil packs” will often fail after a certain point (a common Ford problem) and cause rough running problems.
Of course, there are all sorts of possibilities that could account for a rough-running condition, hard-starting or misfire; these are just a few of the basic scenarios. Is your car running rough? Don’t put it off – make an appointment with us at JBC Tire Complete Auto Care in Springfield or Nixa, MO!