Cylinder compression-

[FlipCoupe]

I checked my compression, only did cylinder 1 and 2-

1 tested at 60, put a cap of oil in and it went to 90
2 tested at 90, put a cap of oil in and it stayed at 90.

This was a borrowed compression tester from a friend, not sure why cylinder 2 tested so low then stayed there. Cylinder 1 isn't firing but has fuel and spark so the 60 to 90 is probably about right.

Im going to rebuild the motor either way, just wondering why cylinder 2 didn't increase compression.

[OutToWinPAHC]

could be more then worn rings... now I have to ask. You sure the compression tester was tight enough in the hole? Because those number are LOW, like really really really low.

[FlipCoupe]

could be more then worn rings... now I have to ask. You sure the compression tester was tight enough in the hole? Because those number are LOW, like really really really low.

to be honest maybe not, i should try again. The first time i did the compression test awhile back I got the tester stuck in my spark plug hole, it would spin but not unscrew, left it overnight and the next morning it unscrewed easily, so im a little gun shy about putting them in too tight.

But even when i put it in that tight cylinder 1 still was testing around 60 and the rest were in the 120+ range.
The only thing that I cant figure out is the car drove fine, didnt overheat or anything, got home and parked it for about a week. (only really drove it around on weekends) Tried to start it up and it didnt sound right, figured out cylinder 1 wasnt firing.

Replaced the fuel injector, tested the plug, tested for spark..everything is there and that's when i checked the compression. Then being an idiot I let someone convince me it could be a valve/head gasket issue, so i took the head off and had the valves checked, they were fine. Then i replaced the headgasket and have the same problem, so now im going to tear it apart again and replace the pistons/rings.

[OutToWinPAHC]

Its needs to be as tight as a spark plug. Also make sure your injectors are unplugged.

[FlipCoupe]

ok ill try again but what i did was
start the car and warm it up.
Then removed the fuel pump fuse until it died
hooked up the compression tester
hooked up the 240 to my daily driver
held gas pedal to floor and cranked it over.

never unplugged my fuel injectors.

[OutToWinPAHC]

Remove plugs, unplug and insulate the coil wire, unplug the injectors, and test it. Just crank it for about 4-8 seconds per cylinder, no need to give it gas or anything

[FlipCoupe]

Remove plugs, unplug and insulate the coil wire, unplug the injectors, and test it. Just crank it for about 4-8 seconds per cylinder, no need to give it gas or anything

ah, i read somewhere to do a compression test at full throttle so i figured that meant gas pedal to the floor.

thanks for your quick responses btw

[breadbox]

If you get low comp in one cylinder, either drive it til you only have 3, or replace that cylinder/might as well rebuild or swap.

But if one has 99 and the rest read 110 it might not be as bad as 60psi in 1 and 110 in the rest. I drove my z24 720 for 3/4 months on on a broken exhaust valve, lots of 70mph highway miles. before I swapped it out to rebuild the head.

[FlipCoupe]

If you get low comp in one cylinder, either drive it til you only have 3, or replace that cylinder/might as well rebuild or swap.

But if one has 99 and the rest read 110 it might not be as bad as 60psi in 1 and 110 in the rest. I drove my z24 720 for 3/4 months on on a broken exhaust valve, lots of 70mph highway miles. before I swapped it out to rebuild the head.

its running on 3 cylinders right now which is why I'm going to do a rebuild. Just going with OEM internals, i don't plan on any type of crazy boost that would require forged. Boost someday...but would like to drive na first lol. Plus im spraying a fine mist of oil from somewhere on the intake side of the motor around the alternator.

Tired of the troubleshooting, time to start fresh