Some years ago I tried to find a Chrysler-minivan with a mysterious miss. A few years ago, a Chrysler minivan had a very slight misfire at idle. However, it disappeared when the throttle was opened. I looked at the electrical system and the fuel supply system before examining the engine. If you want to learn more about How to Choose the Best Automotive Lab Scope?, please visit this page.
This transverse V6 was not showing any vacuum, so the time had come to measure compression. As it turned out, the front and rear banks of this transverse V6 tested slightly low. In my next step, I conducted a cylinder-leakdown test. It was then that I discovered that the exhaust on this cylinder had a small leak.
First, I didn’t test that possibility early in my diagnostic process and wasted a lot of time hoping to find the problem somewhere easier. My first mistake was that I failed to test the possibility of a leakage early on in my diagnostics process. I spent a great deal of time in vain, thinking I would find the solution in’something easier’. In addition, it took time for me to do the tests of leakdown and compressibility. Most transverse engines have a difficult rear bank that is hard to reach. Because the vehicle was under factory warranty and had low miles, it wasn’t necessary for the customer to pay.
And what if that was the case? Can I justify taking 2 hours or more to test these devices if it turns out they are OK? This is when I discovered I could conduct a relative compressed test in only minutes with my digital storage oscilloscope.
As I mentioned earlier, it is my first step in diagnosing any driveability problems. It is important to me that I eliminate as quickly as possible the possibility that the issue could be caused by a mechanical failure.
It is important to note that the relative compression and starter draw are not identical.
First, I was taught starter draw. You have to use current in order to turn the starter. And the higher resistance you face, the bigger the draw. The test was a common one for young technicians to learn how to accurately measure the draw of the starter when testing the system. A scope with the ability to graph and change the time base allows you to easily see what impact each cylinder has on that draw.
To test the starter, clamp your high amp clamp onto the positive battery cable. Switch on your scope. Change the time base from 100ms to 100ms. It is possible to fine tune the adjustments in order to better understand the pattern. Check that your battery has enough power and then disable any fuel, ignition or other systems to stop the engine starting. Just as if you are performing a standard compression test.