Compression Testing

[TMetalMan]

Hey Guys,

I'm gonna do a compression test on my '97 5SFE in a couple hours, but there's something I am not sure about: is it necessary to pull the fuse for the fuel injectors? The Toyota FSM ("Engine Mechanical I4" section) does not state anything about the fuel injectors needing to be turned off, but a little searching around on the web for general compression testing typically says to disable the fuel injectors. My question is: can I leave the fuel injectors in their normal operational state while doing a cylinder compression test?

[TMetalMan]

I just did the test, with the fuel injection system intact. I completely removed the spark plugs wires, and removed the spark plug for the particular cylinder I was testing.

The results are good: #1 and #2 are at about 155psi, and #3 and #4 are at about 170psi. I have an oil leak where I lose about 1qt. of oil every oil change (3000 miles), so this compression test tells me the piston rings and cylinder walls are fine, which I think means that I am not burning oil. Is that correct?

[Gun5]

my car (GFs) definitly speced out at 170-170-180-180 and smokes for a sec on startup so Ill assume valve seals for her

[kegunder]

Be a little careful about causing a big backfire if you do a lot of compression testing while the fuel system is enabled.

Your compressions seems both low and too much diffence between min and max. Be sure that you are turning the engine for long enough to see 3 or 4 compression strokes. Also, try the test when the engine is warm (even though its a pain in the ass.)

[Nad1370]

Just pull the 15amp EFI fuse. Should disable fuel and spark.
Located in the engine compartment fuse block.

Pull all plugs out and wide open throttle, 4 crank rotations on all testing