Troubleshooting engine misfire problems
An engine cylinder misfires when unable to efficiently burn the air/fuel mixture in the combustion chamber. A problem that may lead to all kinds of engine performance issues: You may notice a decrease in engine power, an increase in fuel consumption, higher harmful emissions, or a clogging catalytic converter.Misfire problemsare hard to troubleshoot, though, even for experienced automotive mechanics. Still, cylinder misfires may originate from poor engine maintenance, a key factor in car breakdowns, acknowledges James E. Duffy inModern Automotive Technology. Thus, this short guide can help you find those common sources of engine misfires, even if you don't have much experience in car repair.
Worn out or badignition system componentsis a common source of trouble. If you haven't checked or replaced ignition components during the past 12 months or more, now is to time to do it.
Remove the spark plugs and check for fouled plug tips and incorrect gap. A fouled plug may indicate other problems like oil leaks due to worn out rings or valve seals that can interfere with the combustion process. Also, check that each spark plug has thecorrect gapbetween the electrodes. If necessary, adjust the gap using a wire feeler gauge. Look up the correct gap for your spark plug in your car's manual or service manual.
Then, go over your spark plug wires and check their condition. You may want to check the wires' resistance using an ohmmeter. Typically, spark plug wires shouldn't have more than 12,000 ohms per foot--check your service manual for your model specifications. However, if you haven'tchanged your wiresin more than two years, it might be a good idea to replace them now. Your service manual will give you the correct interval to replace spark plugs, wires and other ignition system components.
Also, carefully inspect the distributor cap, if your engine has one. Look for cracks, corroded terminals and traces of carbon. Carbon traces and damaged ignition components will interfere with the ignition spark and lead to improper combustion.
Damaged vacuum hoses and intake gaskets affect cylinder combustion as well. Consult your vehicle service manual to locate each vacuum hose on your engine and check each hose for wear and damage.
Old and damaged intake manifold gaskets can lead to vacuum leaks. You can use a length of hose to check the gasket. With the engine at idle, put one end of the hose against your ear and use the other end to follow the edge of the intake gasket area. If you suspect a gasket leak, take your vehicle to a repair shop for a more thorough inspection.
Just like insufficient vacuum, a too lean or rich air/fuel mixture will affect proper combustion.
One of the best ways to avoid cylinder misfires is to replace system components, like fuel and ignition parts, at the recommended intervals suggested by your vehicle manufacturer. Your car's service manual, which you can buy at most local parts stores, will help you service, check and troubleshoot many of these components. Locating the cause for a misfire sometimes can be tricky, but remember that in many cases this is just an indication of poor vehicle maintenance.
