Pretty sure my head gasket is bad I am going to compression test it ( 2000, honda, civic, d16y8) I have been reading some people dont unplug the parts before the test and some do, also some say cold engine and some say warm can anyone clarify for me. Do i need to unplug the ecu or anything else

 

Me personally, I do cold engine, unplug ecu, and throttle body at WOT.

 

Unplug the distributor is all you need to do. That will kill the spark and fuel. Not sparking is important because the coil is prone to damage from firing without the spark plug wires hooked up.

 

Ditto the above, kill the spark and fuel, and WOT, but do it with a warm engine and all plugs removed. 94

 

This is how I do it. I think slightly warmed up is the correct way.

-Remove ALL the plugs.
-Remove PGM FI fuse (behind glove box)
-Hold throttle WIDE OPEN
-crank till tester won't go higher.
-Do all 4 cylinders the SAME WAY