How To Read Spark Plugs

The easiest vital sign to read is ignition.

How to read spark plugs. If the color of the ground strap changes too close to the ground strap s end which is above the center electrode then the heat range is too cold meaning that the strap is loosing heat too quickly to the base ring and is not able to burn off deposits until near its end. You will likely see one of the following conditions. Looking at the ground strap and the tip of the porcelain insulator you can quickly see the results of knock or timing adjustments before having to dive. If the tip of the plug is any other color or condition it indicates an issue with either the engine the fuel system or the ignition. To read a spark plug start by checking the color since an undamaged spark plug will be light grey or possibly tan.

Most often a light tan color around the tip of the spark plug indicates a healthy and well performing engine. Look at end of the spark plug that was in the cylinder and examine it. Heat range ground strap the ground strap indicates the heat range of the spark plug. Follow the steps below to learn how to read your carâ s spark plug. Below we share the spark plug reading chart.

Take the spark plug in your hand and begin looking at it for signs of damage. Normal condition an engine s condition can be judged by the appearance of the spark plug s firing end if the firing end of a spark plug is brown or light gray the condition can be judged to be good and the spark plug is functioning optimally. If you notice any black dry soot on the spark plug this is a sign of carbon fouling which means your engine has been running too rich and you should visit a mechanic to figure out the cause. In general a light tan gray color tells you that the spark plug is operating at optimum temperature and that the engine is in good condition. The 7th letter contains data about special spark plug construction features.

Both the fuel mixture and the ignition timing result in coloring of the spark plug s porcelain and ground strap. The 5th position number stands for the heat rating. Other than installing thermo coupler sensors in the combustion chambers the only real way that you know what is happening inside your engine is to read the spark plugs.