Almost every compression testing guide tells you to hold the engine’s throttle wide open during a compression test, but most won’t tell you why it may (or may not) matter.
Long and short-term fuel trim are very useful indicators of engine performance relative to the manufacturer’s specifications, but before we get into what they tell you, we’ll go over what they are.
There are a few different tests for oxygen sensors (also known as lambda sensors), some of which can be run without dedicated tools. The most effective tests tend to be done under normal operating conditions, on a sensor installed on an engine system, though there are some tests which can be done off-vehicle. You can test oxygen sensors with the following tools: Multimeters Clamp-Meters Oscilloscopes The ST05 Oxygen Sensor Tester Caution: Be sure to follow the oxygen sensor manufacturer’s precautions when testing, as well as the tool manufacturer’s directions, and read the vehicle (or other system) service manual before doing any test. Oxygen sensors get very hot when in use, be careful! But wait! Before testing anything, you need to know what kind of sensor you are working with, and where it is.
Glow plugs are installed on many diesel engines to help with cold starts. They usually fail because of corrosion, overheating, mechanical damage, or metal fatigue, and their failure can cause a variety of problems. The easiest way to test a glow plug is by using a clamp-meter, though digital multimeters can also do the job, and glow-plug testers also work. We will cover the following topics in this post: What is a Glow Plug? What are the Symptoms of a Failing Glow Plug? How to Test Glow Plugs with a Clamp-Meter How to Test Glow Plugs with a Digital Multimeter How to Test Glow Plugs with a Glow Plug Tester Caution: Be careful to follow the glow plug manufacturer’s precautions when testing, as well as the test tool’s directions/manual, and read the vehicle (or other system) manual before doing any test.
Most battery testers have two clips (or test leads), you first attach these to the battery’s terminals (connectors), then you press a button (or switch), and a few seconds later, the tester displays or prints a result indicating the battery’s condition. The details of you use a battery tester depends on what kind of battery you have, the electrical system it is connected to, and which tester you plan to use. Some battery testers require disconnecting the battery from the vehicle, while others have different limitations. Most battery testers only work on one, or a few different types of batteries. We describe how to use five different battery testers below: