Since your car requires fuel, air and ignition in order for the motor to function, the very first sign that there may be something wrong with your ignition system is that your car won't run at all. Aside from that though, there are a few symptoms that indicate that there's a fault somewhere in the mix, and below are a few of the most common ones:
- Car feels slow / down on power
- Lumpy idle / misfiring
- Blowing excessive smoke (Smell of unburnt fuel)
- Reduced fuel efficiency
- Car is hard to start
- Check engine light is on
If your car isn't running at its best, the issue will pretty much always come down to fuel supply, air supply and correct ignition. Since this article is focussed on the latter, we'll look at a few of the probable causes and what can be done to remedy them.
The most likely culprits (in a petrol engine) for issues with the ignition system are the spark plugs. If a spark plug gets worn or damaged, then the current will be unable to jump across the gap at the end of the plug. This will mean that the fuel in the combustion chamber won't get burnt properly if at all, and so will drop the power output of your motor considerably. The issue can also arise from any other component in the ignition system, but since spark plugs are the easiest and cheapest part to replace, it's always a good idea to start there and work your way back. As an added bonus, checking the condition of your spark plugs can provide clues as to the cause, should the issue lie outside of your ignition system. A single problematic spark plug may also result in a lumpy idle or occasional misfires, and although this usually indicates that only the one spark plug is faulty, it is always a good idea to replace them all together.
The next part to check in a mechanical ignition system is the spark plug leads. These are usually made from temperature resistant rubber, and although specially designed to withstand the heat from your motor over a very long period of time - like everything - they can fail. Cracks in the cables can allow the spark current to short out onto the engine, resulting in a weak or nonexistent spark. They may also cause a nasty shock, so should always be replaced if they are damaged or worn.
Issues with the distributor are most commonly limited to the contacts in the cap, or a worn rotor. These are easily and cheaply replaced, however, if the damage is caused by a bad seal, then it is imperative that this is addressed to prevent the issue from arising again. Mechanical failure of the distributor assembly will usually require a complete replacement, though even changing an entire distributor can be quite a simple job. Be sure to mark its position if removing the distributor, cap or rotor, as misaligning any part may result in failure to run, or actual damage to your engine. In systems that lack a distributor, you aren't going to face wear caused by moving parts. However, coil on plug and wasted spark systems can still fail. Usually, this will be the result of tiny fractures in the coil casing, and so the entire coil will need to be replaced. Be sure to check the others, since if one fails, then the others may be just about to!
Other issues with your ignition system may be the result of the computer that runs the show. Usually, if a check engine light accompanies one of the other common symptoms, but that part itself seems okay, then the issue will either be with a sensor or with the engine management. Most modern cars can be diagnosed with faults using fancy machines and computers. If the problem is of a more complex electronic nature or if your car's computer has figured out that something's wrong before you have, then it is best to have this done as it can save many headaches involved in tracking down a gremlin the old-school way.
Smokey Starts For Diesels
Even though the most common cause for this is faulty glow plugs, excessive smoke can also be caused by over-fuelling (especially if it happens when you're accelerating hard.) - Always be sure to rule this out first before shelling out for new plugs!
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