Weekly waveform 15 - Cooling system pulse sensor test. Does it have a bad head gasket?

For this test we need a pressure transducer(absolute pressure sensor) or a pulse sensor(delta sensor). I got the best result by performing a cranking test with the pulse sensor or pressure transducer connected to the radiator. I was able to give myself a sync channel by removing one spark plug and adding the relative compression test into the mix. I performed a voltage only RC test by connecting one channel to the battery positive and negative, I changed my settings to AC coupling and inverted the waveform to mimic an amp clamp. 1-2 volt scale will work for this test.

If I was working on a vehicle with an injector fuse or that had clear-flood mode I could have used a sync channel connected to a spark plug wire or ignition coil. The waste fire system on this Toyota also limited us on the sync.

With everything connected we can crank the engine over and analyze the results.

I performed this test on a 1998 toyota 4runner that I replaced headgaskets on a year ago. It has the 5vzfe 3.4 DOHC engine and it is somewhat common for head gasket failure. Once I removed and inspected the the cylinder heads I found a couple of small cracks in cylinder 4 and cylinder 6. I don't know if the machine shop and myself missed the cracks when I replaced the headgaskets or if the cracks developed or grew after the last repair. Keep in mind the customer only recently started having issues with a misfire on startup.