If your car struggles to start but runs fine, there are numerous potential causes. This guide will run through a few of them, explaining why your engine’s finding it so laborious and what you can do to remedy it.
Apart from mechanical wear and failure, a few other factors can make a difference, such as the climate, temperature, fuel type and quality, and vehicle durability.
Check for any lights on your dashboard, too. These can be extremely enlightening.
Although you’ll find a few different ideas on this page, there’s no substitute for an in-person diagnosis from a skilled mechanic.
Specialized equipment such as battery testers and OBD II code readers (both of which you can acquire for yourself if you like) are crucial here.
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Electrical System
If your car has trouble starting but runs well, it’s most likely due to a minor fault in the electrical system.
There are many other possibilities you should consider, too, of course. Still, an electrical inspection will likely solve this issue for the majority of drivers.
Remember, it’s not necessarily about the battery. The electrical system also comprises a few other crucial players: the starter motor, the key, the alternator, and miles of wiring.
Starter Motor
The starter motor (or related issues) will be the cause in numerous cases. This is especially true if you find that the car struggles to start, but the battery is fine.
The starter motor is connected to a circuit that includes the ignition key and the battery. An electrical current is sent to the motor when you turn the key.
It then pushes its pinion to mesh with the engine flywheel. Electricity powers this tiny pinion with high torque, cranking the engine and giving it the impulse it needs to start. It’ll then run under its own impetus.
If the starter motor has developed a wear-related problem and isn’t functioning properly, it’ll be challenging to crank the engine. As a result, the car struggles to start.
Check the starter motor’s condition using a specialized battery tester, saving the need to remove it from the vehicle. If you find that it’s in poor condition, it’ll need rebuilding or, more likely, replacing.
Battery Or Alternator
The battery and alternator work together to create and store electricity. The alternator is driven by the belt connected to the crankshaft and replenishes the battery during engine operation. Then, the battery supplies power to both the engine and electrical components in the vehicle.
When you turn the key in the car, the battery gives power. The engine isn’t running yet, so the alternator isn’t doing anything. If the battery is feeble, it won’t send sufficient power to the starter motor.
This could be caused by a couple of things. If the battery has a crack, leak, or other damage, it won’t be able to hold a charge. Similarly, if the alternator isn’t functioning at its usual rate due to an internal fault, loose pulley, or slack belt, it won’t recharge the battery quickly enough.
A final vital factor is the length of your journeys. It can take a battery half an hour of highway driving to recharge fully.
If you take lots of shorter, halting city trips, your battery will wear out much faster. Take your car for an hour-long swift cruise up and down the freeway to see if the problem persists.
Again, a battery tester is the ideal solution here. It’ll reveal any problems with either the battery or the alternator. These can then be replaced if necessary.
Bad Wiring
Faulty wiring could be why your car is difficult to start but runs fine. There are miles of wiring looms within a modern vehicle, so start with the ignition wiring and connections to the starter motor.
The starter motor circuit is activated when you turn the key to START. If there’s an issue here, it could be sending less power than it should.
Unless you’re an electrical specialist yourself and have access to your own equipment (multimeters and such), this may require professional diagnosis. Take your car to an automotive electrician and go from there. Unfortunately, this can be rather expensive, but there could be no way around it.
It’s wise to rule out other possible causes before investing in electrical diagnosis.
Engine Components
Almost any engine component, if functioning improperly, could lead to this issue. Aside from those mentioned below, consider checking the ignition timing, camshaft, timing belt, distributor cap, and all filters (air, oil, and fuel).
Spark Plugs
Over time, the spark plug gap can widen. As such, they require more electrical power for a spark to bridge the aforementioned gap.
You could notice this when starting because the motor might need to crank longer than usual before it gets going. However, once the alternator’s operating with the engine at higher revs, the spark plug gap might be substantially less of a notable problem.
Fixing this requires re-adjusting the spark plugs. Although you’ll need some depth gauges, it’s a relatively straightforward process. Alternatively, you could change all the spark plugs for new ones (something that needs to be done fairly regularly anyway).
You can also get carbon buildup on old spark plugs, leading to a similar problem. You’ll notice a black soot-like grit covering the parts. They’ll need replacing.
Fuel Injectors
The fuel injectors’ jobs are to inject the fuel (big surprise!) into the engine. They’re controlled by electronics and specifically designed to put an exact amount of gas or diesel into the combustion chamber.
If the fuel injector fails to insert sufficient fuel (or too much), the resulting air/fuel mixture won’t burn properly. This will lead to the engine struggling to start.
The problem is expected to persist while the car is in motion. But if it’s only a minor issue, you may not notice it as much when the engine starts.
Faulty injectors will need replacing. You can use a multimeter to check whether each element is working. An OBD II code reader may also give you your answer. You should only expect one or two to fail at any specific time.
For any more to cease working would be very unusual and probably indicates a deeper electrical issue.
Weather
Believe it or not, the weather can significantly impact your vehicle, especially while starting – cold weather, in particular. Cars don’t like negative temperatures, harsh winds, snow, ice, or freezing fog/rain.
When it’s winter, all the fluids in a car are either thicker or freeze completely. Fuel and motor oil both struggle to flow until they warm up. Water in batteries can freeze, leading to low power (or none at all!).
In frigid climates, such as the northern states, Canada, Scandinavia, or Russia, cars might frequently need a boost from a battery charger to get them going in the morning.
Once the car is running, though, it should warm up within ten or fifteen minutes, and everything should operate as normal from there.
So, is it a frosty day? Or perhaps a mild day with a chilly blast coming out of the north? Even an extremely humid day? Any of these could be why your car’s hard to start when cold but then runs fine.
The ideal option is to park your car in a shelter like a garage or even a makeshift tent. It’s not a perfect solution, but it might make a difference.
Be cautious with carbon monoxide exhaust fumes when starting the vehicle. These can be lethal if you don’t open the doors before starting the car.
Space heaters are also an alternative but aren’t advised. They’re known to cause fires.
Concluding Thoughts
When an engine struggles to start but seems fine once it’s going, it needs diagnosing as soon as possible. Although it might feel like an annoyance, it’ll be a real bother if you drive 20 miles to work and then get stuck there when the car won’t turn on.
You can check, eliminate, or confirm many potential causes yourself using DIY tools. Start by considering the weather’s impact, then examine the ignition, electrical systems, and essential engine parts.
If you can’t locate the issue’s source, take your car to a dependable local mechanic. Getting it repaired as swiftly as possible is likely to save you much more in future costs.