Engine 2JZ-GE, 6 in-line cylinders. I can only get access to spark plugs in cylinders 1, 2, and 6. In order to get to the remaining spark plugs, I need to remove the whole throttle body, which is a real pain in the rear.
1. Can I unscrew only 3 spark plugs, remove ignition and fuel injection fuses, and do the compression test for the three cylinders?
Below is a quote from quora, which I don't trust:
If you leave plugs in but pull the ignition and/or fuel pump so it can't run the pressure will be low as cranking speed will be too slow.
2. Is that true? Why would the cranking speed be slow in that case?
Another quote:
Hold the throttle to the floor while cranking. A closed or part open throttle will give low readings.
3. Is that true? Why would a closed or partly open throttle valve give low readings?
Neither of those statements are true.
If you just want to know if you have a weak cylinder, why not do a relative compression test 1st?
https://youtu.be/RLOpo71JtIU?t=175
Thanks for the video. I got the answer from the video that I can pull out only one spark plug at a time and do the test. The alternative method with a low amp probe and a graphing meter sounds good too, but the tools are expensive and I could not find any auto parts store that loans you the tools.
P.S. I wish Scotty could make his videos titles more descriptive for easier search instead of "You are stupid if you do this; Pray if you see that, etc."