High internal resistance in spark plugs is rapidly becoming a concern that many IA/AP's are beginning to recognize as the source of rough running engines and chronic magneto related problems. Since a growing number of maintenance facilities are incorporating a resistance check of all spark plugs, Tempest felt it would be beneficial to make it as easy and efficient as possible to conduct such a test.
AT5K Resistance Tester
The IA/AP simply places the spark plug, barrel side down over the contact post and touches the other lead end to the firing end of the center electrode. If the light is green, the spark plug resistance is below 4kŮ (thousand ohms). If both the green and red lights are on, then the plug is between 4 - 5kŮ. This is acceptable for serviceable plugs. If the red light is on alone, this indicates a resistance value in excess of 5kŮ and the plug must be discarded and replaced.
Would prefer a built in OHM gauge on the unit, but the unit is well made and should provide years of good service. It is easy to use
Both O-rings pulled off on the first plug. Other than that it works great. I found the faulty plug that had been bothering me right away. What a time saver.
Seems to work well, very easy to use.
Works great, simple and quick. No reason not to check plugs when they are out when you have this great little unit. You can accomplish the same thing with an ammeter but not as quick and easy. Im happy with it, highly recommend.
Yes, both plugs types will work fine with this tester.
Per the supplier: Yes, it will work with both types of plugs.
This is powered with a 9V battery.