CAR CLINIC

How to know it’s time to have your car’s spark plugs changed

In Summary

•Other than high fuel consumption it’s easy to tell any slight loss of power on this kind of engine especially on high end boosts.

•A turbo charged Subaru that needs plug replacing would somehow hesitate or take time to attain higher speeds.

Spark plugs.
Spark plugs.
Image: COURTESY

The plugs are the main source of a spark within your combustion chamber. Without them, automatically there will be no spark. Why does this matter?

Well, because a strong spark means a stronger flame which equals good power thus higher turning force at the cranshaft which translates to overall vehicle power.

You will have a healthy engine (low revs, high power) when you get spark plugs, low fuel consumption and a powerful car altogether.

Every car has a specific plug and a specific duration measured in kms/miles.

In the case of a Subaru, for instance, most 2000cc and above older generation vehicles ( both turbo and non-turbo) would require the plugs to last at least 2,0000km before replacement.

The new generation for the same would require the plugs to last twice the amount of tima as the older generation.

Meanwhile, some of the 1500 cc Imprezzas would require plugs to be replaced during every service; most of them would also last upto 2,0000km.

The big question would be how do I know it’s time to replace my plugs.

There are many ways to know you need to replace the plugs.

The easiest of them all would be if you own a turbo charged Subaru and you are a frequent user of the same.

Other than high fuel consumption it’s easy to tell any slight loss of power on this kind of engine especially on high end boosts; a turbo charged Subaru that needs plug replacing would somehow hesitate or take time to attain higher speeds.

This is made easier if your car is fitted with a boost gauge. Less amount of boost generated by your turbo would be easily noticed at the boost gauge.

This would be easily picked by the driver which would suggest that all is not well at the combustion chamber.

Most motorists who drive a turbo charged Subaru would always find it easy to tell when they need plug replacing.

For the non-turbo Subarus, high fuel consumption and inability of the car to pick up speed completely especially when going uphill is the most common way to know it’s time to carry out plug replacement.

Hard starts in the morning on first start ups and erratic idling or complete lack of idling when the engine is still cold is also another way of knowing that maybe it’s time to do your plug replacing.

All in all, it’s always good to keep track /follow your service schedules in order to know exactly when to replace your plugs so that you don’t wait for the above signs because by the time they are happening its usually too late.

Sometimes in the new generation Subarus. delayed plug replacement may trigger a check engine light and when a scan tool is plugged in, it says ignition secondary faulty.

This is why we insist on following the service tag. This is evident from the pictures below; the plugs are from a car that had been completely neglected in terms of plug replacement.

Comparing the centre eletrode on the older plug and the newer plug we shall all agree that the plug was badly off.

The writer is the owner of Boosted Auto automotive repair shop

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