Introduction

Spark plugs seem to be such a modern innovation that it comes as quite a surprise that they have actually been around since the 1830s.
Those early versions were used in low speed low compression petrol engines with an engine life of about six hundred miles so spark plugs have come along long way since then in the terms of efficiency service life and design.

Now today's spark plugs are the cutting edge of technology lasting up to 60,000 miles of driving and can outlast even the engine when you consider they have to with stand searing heat and temperature that's certainly and incredible feat....the advances made in spark plug technology have been many but today r&d across the world is being driven by just a few common factors .

Spark plugs in its simplest form comprised of just a shell an isolator and a conductor and to operate the plug its connected to high voltage generated by an ignition coil this high voltage is suppied to the spark plug creating a spark between the centre and ground electrodes ..the spark ignites the air/fuel mixture resulting in combustion inside the cylinder and causing the engine to start up.

Now on a smaller size of electrode the more powerful the spark resulting reduced emissions and lower fuel consumption and improved engine efficiency..create extremely small centre electrodes as well as longer life precious metals are needed and the exceptional characteristics of metals such as iridium /rhodium and platinum means that manufacturers are now able to produce much tinier electrodes which in turn create a more powerful spark providing consistant and powerful ignition over many thousands of miles of driving.

Overheating

Appearance of the plug will be that the insulator will be chalky white in appearance with no tan colouring, pitted or blistering electrodes and in some cases, the insulator will begin to turn dark blue or even grey in colour.

The cause can be an incorrect heat range for the plug ..lean air/fuel mixture, ignition timing incorrectly set, insufficient plug tightening or even general engine over heating.

The remedy for this is to Identify the cause of the over heating and to rectify and replace the plugs with a set of new plugs recommended by the manufacturer.

Oil Fouling

This is where the end of the plug is wet in appearance and contaminated with oil ..this can and is usually a sign of advances engine wear and oil is bypassing in the cylinders ..although oil can also bypass from the crank breather system this will result in the spark not jumping the gap to the ground electrode ..the only course of action here would be to investigate the cause of engine wear and rectify and insert new plugs on assembly do not in any way try to re clean the old spark plugs.

Don't be a cheap skate ..buy new!

Generally Worn Plugs

The appearance of a worn out plug will be the centre and/or ground electrodes are well rounded and the gap between the two will be very excessive.

This plug has now come to the end of its life and the only course of action will be to replace it. I will stress here that the increased gap will multiply the workload of the engine and will cause repeated miss firing, poor fuel economy and damage to other ignition components. Replacement is the only course of action!

Using Fuel Additives

Fuel additives and the use of in the engine will give a distinctive reddish/brown or purple deposit on the core nose insulator. Additives are normally non-conductive, however some are and if the deposits build up in excess it can create an earth leakage path for the spark. The remedy for this would be to replace the plugs and if you still wish to continue the use of additives. Make sure additives are compatible with the engine and ignition systems and are added in the correct ratio/proportion.

Tracking

You will identify this by the tell tale black burn marks running down the spark plug insulator towards the main shell of the plug. What is happening here is a current discharging from the top of the plug down the outside of the insulator and to earth, effects of this will be engine misfiring. The only course of action is to replace the plugs and if the car has HT leads then this would be an advisable too.


NGK Iridium Plugs

Having the smallest center electrode in the world at 0.4mm the iridium plug delivers exceptionally high performance but an even more recent innovation looks set to pugs the boundaries still further. The SIP or super ignition plug features two tiny central electrodes for an even greater spark and performance.

Plugs that feature precious metal electrodes are not just prized for their greater durability as they are also prized with effectively assisting low emissions and this is why spark plugs that use precious metals continue to be a continual focus of R&D. The exceptional spark produced by an iridium spark plug electrode reduces cooling loss gives superior performance and much linger life and this makes the iridium plug a valuable weapon for manufacturers who are continually fighting to lower emissions on today's vehicles - you only have to look at the Japanese market to see that the manufactures there are using the iridium plug now on 80% of all new cars they produce. Where the European market are further behind with platinum and nickel based plugs . It would seem as if the subject will soon be addressed and a change in the future is definitely on the cards .