A Peek Inside: In-Cylinder Pressure Testing For Driveability Diagnosis
Duration: 24 minutes and 35 seconds
Have you ever stood peering into the engine compartment, scratching your head and wishing you could see inside the engine when faced with a drive-ability complaint? Wouldn't so many problems be easier to find if you could? Imagine being able to see exactly when the ignition event actually happened, or confirm that a valve that wasn't sealing as it should? How about verifying cam/crank synchronization without the need for a "known good" cam/crank sensor waveform or tearing the engine apart to access the physical timing marks?
You could do all this and more in minutes if you were using in-cylinder pressure testing as part of your diagnostic assault!
This test uses a pressure transducer and a digital storage oscilloscope (DSO) to monitor pressure changes in the cylinder while the engine is running. A transducer differs from a sensor in that the transducer is able to accurately measure the pressure while a sensor simply reacts to pressure change. The transducer converts the pressure measurements into a voltage signal that your scope can use to paint a picture of these changes on the scope's screen, bringing the idea of a traditional running compression test into the 21st century!
In this edition of The Trainer, we'll show you how what accessories you'll need and how to set up a scope to perform this test. We'll also show you the basic elements of the in-cylinder running pressure waveform, and what they have to tell you. After viewing this video, we're sure you'll see how valuable a technique this is and how it can save you hours of time in the shop!
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