Adding to our range of diagnostic equipment we now have a Hantek DSO-3064 Oscilloscope
This advanced 4 channel Oscilloscope comes with a vast range of test probes and current measuring clamps, this allows us to capture the fast signals modern sensor produce.
With the current clamp we can also measure small and high current draw, this lets us carry out relative cylinder compression tests without removing the spark plugs. Because a cylinder with lower compression provides less draw on the starter motor so connecting the current clamp to the main starter lead and cranking we get a waveform off current used to crank the engine over
Testing the compressions on a VW Polo 1.4 using the Scope.
I only saved the waveform for channel 1, so Ive added a Red line for Cylinder 1 marker.
As the compression is measured in firing order the peaks go 1-3-4-2
So cylinders 1(Red)+3(Green) have good compression and cylinder 4(Brown)+2(White) have low compression’s