In a traditional gas-powered engine, gasoline is fed into the combustion chamber where it gets ignited to create the necessary explosion for firing up the engine. And, it’s the spark plugs that set everything off. So, if you’re having problems with starting the motor, chances are, the plugs are acting up. But how can you be 100% sure of that? Maybe you’re simply out of fuel, or maybe it’s a completely different problem?
Good news: there’s a (relatively) easy way to check the ignition system manually, without asking a mechanic for help. All you’ll have to do is follow my guide! First, we’ll find a way into the engine bay. Then, we’ll inspect the wires, move on to the coil, the distributor, and check for spark. The whole process will take 30-40 minutes, or less!
#1: Getting Ready
To get this done the right way, start by parking the vehicle on an even surface. Next, buy a pair of high-quality protective gloves and eye goggles. Remember: you’re dealing with electricity here, which means you can never be too careful. Don’t turn the engine off, though, because you won’t be able to check the plugs then. Now, before you move on to the “meat and potatoes”, it would be wise to check the fuel levels.
Chances are, you’re running low on the “engine juice”, and that’s what’s causing all the trouble. Then, check on the battery: it should have a strong enough charge for the spark plugs to do their thing. So, turn the headlights on – if they’re not as bright as they should be, a replacement is in order. Another thing to scan is the fuse box. Do you see a black/burnt spot? That means the fuse is blown.
And don’t forget to disable the fuel system/injector. This can be done by taking the pump relay/fuse off. If you skip this part, the cylinders will be filling up with fuel while you’re busy checking the plugs. There’s also a shortlist of tools that you’ll need for this. Most importantly, invest in a spark plug tester. This tool makes it very easy to check the plugs for spark. A multimeter, a test light, a wrench, and a screwdriver will come in handy as well.
#2: Starting with the Spark Wires
If you’re driving a relatively new car, the engine will be protected by a cover. Remove it to get access to the plugs. You’ll find them right on top of the engine, or on both sides of it. Spark plugs come with wires – they hold (or, rather, carry) high voltage. So, be very careful. What you should do here is grab the plug tester and put it into the end of the wire that’s called the plug boot. Next, ground the tool.
For that, use a clean (unpainted) metallic surface; the engine will be great for this. Now go ahead and start the engine up, or, better yet, ask a buddy to do that for you. Do you see a strong spark on all wires? Then maybe the issue is with the timing. And if there’s no spark (or if it’s too weak), I bet the problem is within the ignition system. Moving on, do you know what a distributor cap is?
It’s got only one job: to absorb the voltage generated by the ignition coil and to deliver it to the plugs. It won’t be hard to find the distributor: just follow the spark plug wires, and you’ll see it. The distributor has a set of screws holding it steadily. I want you to remove them to get to the rotor. Again, ask the buddy to fire up the engine. Is the distributor turning, or is it standing still? If it’s the latter, then it’s the timing belt that’s causing the problem.
#3: Moving on to the Ignition Coil
Now we need to inspect the ignition coil and check whether it’s the root of the problem or not. If the buddy is still around, tell him to turn the ignition key. Don’t fire up the engine just yet, though. By turning the key, you activate the ignition system, and that’s exactly what we’re going for here. In this mode, it will be much easier to find out which wires and components are getting enough electricity, and which ones are “starving”.
As I already mentioned, it’s the ignition coil that generates the necessary voltage for the plugs. You need to locate it. It’s got three wires: one’s running into the distributor, the other one is the positive power wire (it connects the coil to the ignition switch), and the last one is the negative wire (responsible for grounding).
#4: Dealing with the Ignition Wires
Grab the test light and use it on the positive wire. No power? That means only one thing: the ignition coil isn’t getting the current it needs to start the engine. Chances are, the positive/power wire is worn out or even broken. If that’s the case, you’ll have to repair or replace it. And if there are no problems with the power, just leave this wire alone, and switch your attention to the negative one.
Also known as the ground wire, it can be checked with the same test light. With the key inside the ignition and the engine turned off, the test light should, well, light up when it comes in contact with the negative wire. If that doesn’t happen, then – yep, you guessed – replacement is in order. So, if both the positive and the negative wires are working properly, go ahead and crank up the engine.
Ask that friend of yours to start it and keep your eyes on the test light. Do you notice flickering? Grab the multimeter (or just a regular ohmmeter) and measure the ignition coil’s resistance. But how do you know the right measurements for it? Refer to the service manual – it should include all the necessary information. If the readings are wrong, you’ll have to replace the coil.
#5: Checking the Distributor
Alright, this is our last stop. We’ve inspected the spark wires, the ignition coil, and the positive and negative wires. All that’s left to do is check the distributor. We’re mainly interested in the pulse generator. Follow the wires from the ignition module: they come right into the generator. Is the multimeter still around? Connect it to the wiring and start the engine.
No current means trouble with the pulse generator. A strong current, in contrast, means there’s nothing wrong with the distributor. Where are all the bodies buried, then? My money is on the ignition module: it’s malfunctioning, preventing the engine from getting a proper spark. The last thing you want to do is inspect the ECM (engine control module). It can only be found in newer vehicles, though.
Without a spark, there can be no ignition, meaning the vehicle won’t start. That’s why it’s very important to make sure the ignition system is working flawlessly. Otherwise, you’ll spend lots of time and energy trying to get the car started. Today, we learned how to inspect not only the spark plugs but also the ignition coil and the distributor. This will save you an expensive trip to the closest service shop.
Now, regardless of what component of the system is faulty, fixing this problem won’t cost you a fortune. For example, a set of brand-new ignition coils is available for 30-40 US dollars. Spark plug wires are even less expensive ($20-30 max). So, if the spark plugs are acting up, don’t hesitate to pop the hood and get your hands dirty!