Spark Plug

Gasoline engine obtain power by compressing fuel/ air mixture of air and gasoline, and exploding this mixture by ignition.

Spark plug serves to ignite this fuel/air mixture.

With the battery as the power source, the spark plug converts the electrode energy that comes through the ignition coil and distributes into a spark which ignites the fuel/air mixture.

In other words, without the spark plug, the engine doesn’t run; the spark plug is an important part because its performance influences the overall performance of the engine.

When the high voltage generated by an igniter is applied on the center electrode and the ground electrode, electrical spark is produced, because the insulator between the electrodes is broken resulting in discharge there. This spark energy can fire compressed air/fuel mixture.

This process is conducted so rapidly (1/1000 seconds).

The role of the plug is to ignite the air/fuel mixture to turn it into work while accuracy and powerful sparks are required.

Ignition produced by electrical sparks result due to particles existing in the spark gap become activated which leads to chemical reaction bringing about flame kernel. This reaction is generally bigger and bigger in the spark gap.

However, when quenching effect is bigger than the heat generation, which turn out misfiring, a wider spark gap can be expected to generate powerful ignition, because the flame kernel can develop bigger in the wider spark gap and the quenching effect become less.

However this setting requires larger discharge voltage which is over the limit of a coil ability just leading to misfire.

3. Types of spark plugs available

Nickel Standard Spark Plug
Iridium Spark Plug
	Iridium Power	Iridium Racing	Iridium Tough
TT Spark Plug
	Nickel TT	Platinum TT	Iridium TT

1. Comparing Appearance

2. Comparing Section

3. Problems Caused By Fake Spark Plugs

Inconsistent sparking causes incomplete combustion. Unburned fuel forms a black sooty deposit on the spark plug, eventually leading to poor fuel economy and poor start up of the engine.

Poor heat dissipation due to the lack of a copper-core center electrode causes pre-ignition. As a result, engine power drops under highway driving or uphill driving conditions.

Continued usage of an overheated plug will damage the electrodes.

Quick heat dissipation.

Copper is an excellent heat conductor. High temperature heat is quickly dissipated away from the center-electrode to prevent melt-down.

Slow heat dissipation.

Absence of a copper-core center electrode results in poor heat dissipation capability. Prolonged use causes power loss due to excessive heat build up.

This results in melt-down of the ground electrode, eventually leading to serious engine damage.

IN NO EVENT SHALL DENSO BE LIABLE FOR ANY LOSSES, EXPENSES OR DAMAGES WHATSOEVER  RESULTING FROM ANY OF THE FOLLOWINGS;

- FAILURE TO COMPLY WITH THE WARNING OR PRECAUTIONS DESCRIBED IN THIS CATALOGUE AND WEBSITE,

- ANY USES OTHER THAN THE APPLICABLE USE DESCRIBED IN THIS CATALOGUE AND WEBSITE, and

- ANY TROUBLE NOT ATTRIBUTABLE TO DENSO SPARK PLUGS.

※”Spark plugs” means any type of DENSO’s spark plugs, including but not limited to Iridium Power, Iridium TT, Iridium

     Racing, Iridium Plus, and Iridium Tough, Iridium Long Life, Double Platinum, U-Groove, Resistor, Standard, Nickel TT,

     Platinum TT, Two-Tops.

● Never use DENSO spark plugs in the engines for any aircraft, including airplanes, helicopters, gliders and drones. The DENSO spark plugs sold are not designed and manufactured for any aircraft:  use may result in a plane crash or other accidents due to engine malfunction.

● Never use DENSO spark plugs, listed in this catalogue, in the engines for generator and gas heat pump air conditioning system. The DENSO spark plugs we sell are not designed and manufactured for such use, so that such use may result in accidents, including power generation stop or heat generation stop.

    A separate catalogue for DENSO spark plug specifically designed for generators (gas engines) is available. Please contact your DENSO representative for more information.

● Never use DENSO spark plugs for gas burner ignition. The DENSO spark plugs we sell are not designed and  manufactured for such use, so that such use may result in ignition failure or equipment damage due to overheating.

● Be sure to turn off the engine and disconnect the battery before replacing or adjusting the plugs. Failure to heed this warning may result in a fire, an electric shock and/or bodily harm.

● Always refer to the vehicle manufacturer’s repair manual for specific installation procedures.

● Carefully read the instructions and precautions on the package, catalogue and website.

● Do not drop spark plugs. This may cause the spark plug to crack internally or the gap to be narrowed, preventing it from functioning correctly.

● If Spark Plug needs to be gapped, bend from the back of the ground strap with appropriate tools. Do not physically adjust gap using the center electrode as leverage. Check gaps with care, not to damage the center electrode. Gap to the vehicle specific manufacturer’s recommendation unless otherwise recommended.

 Modified Vehicles and Tuning Precautions

● DENSO will not bear any responsibility whatsoever for any trouble arising from mechanically or electronically modified engines or vehicles.

● It is the user’s judgement and responsibility to check the specifications required for modified engines, which includes and not limited to, gapping, heat ranges, reach, projection, and/or clearances with valves and/or pistons.

 Catalogue & Website Precautions

● Precautions for cross reference and product tables showing other manufacturer’s spark plugs:

    ◆ Use for reference only. Table does not guarantee the performance of spark plugs when installed in the vehicles if plug was specified using cross references. Always check the applications section for DENSO recommended plugs.

    ◆ The spark plug specifications (construction, material, etc.) differ from one manufacturer to another.

    ◆ Select a suitable type of spark plug from the vehicle application table.  If not listed on the table, please check with your DENSO Representative.

● The contents of the catalogue and website are updated on a regular basis, but they cannot account for daily dynamic changes such as new applications and or OE supersessions. If there is an issue with the information, please contact your DENSO Representative for further assistance.

● Consumption tax and installation fees are not included in the price of the product.

● Some spark plugs on this catalogue and website are manufacturer’s genuine parts that listed for reference and cannot be directly sold. Please contact your DENSO representative for further assistance.

● The appearance and specifications of the product are subject to change without prior notice.

● The images of spark plugs indicated in the catalogue and website are conceptual diagrams, and sometimes differ from the actual products.

When using unleaded gasoline, the base of the insulator often becomes white or gray. The electrodes may become slightly burned.

When using leaded gasoline, the base of the insulator becomes light brown.

1. Inappropriate thermal value
2. Engine idling for a long time, or driving in low temperatures
3. Rich air-fuel mixture
4. Clogged air filter
5. Delay in ignition timing

1. Oil leakage into the combustion chamber due to frictional wear of the piston rings, valve guides, or cylinder wall
2. Rich air-fuel mixture

1 or 2: Use a spark plug with a thermal value that is one level lower, or adjust engine idling

3 to 5: Perform complete re-adjustment and tune-up

1. Spark plugs may become wet until the oil flow control becomes normal during pre-conditioning runs with a new engine or an engine immediately after an overhaul. In such cases, simply clean the plug and reinstall it. In other cases, the engine basically requires a complete overhaul.
2. Adjust the carburetor.

The base of the insulator will be burned and become bleach white from the heat.

The electrode will also be burned and become white or dark purple.

Electrodes will wear out soon.

This is caused by overheating.

Temperatures in the combustion chamber increases rapidly, destroying not only the spark plug, but the piston head too.

1. Inappropriate thermal value of plug
2. Use of low octane gasoline
3. Ignition timing set too early
4. Inappropriate cooling
5. Poor air-fuel mixture

1. Inappropriate thermal value of plug
2. Use of low octane gasoline
3. Ignition timing set too early
4. Inappropriate cooling
5. Poor air-fuel mixture

1. Inappropriate thermal value of plug
2. Ignition timing set too early
3. Inappropriate cooling
4. Poor air-fuel mixture

1. Use a spark plug with a higher thermal value
2. Use higher octane gasoline
3. Adjust the ignition timing
4. Check the cooling system
5. Adjust the carburetor

1. Use a spark plug with a higher thermal value
2. Use higher octane gasoline
3. Adjust the ignition timing
4. Check the cooling system
5. Adjust the carburetor

1. Use a spark plug with a higher thermal value
2. Adjust the ignition timing
3. Check the cooling system
4. Adjust the carburetor