Hi guys,

i am trying to perform a compression test on my cobalt and id just like to get a few pointers if you guys dont mind...


I disconnected the grey fuse for fuel pump , and when i tried to start it to let it run til it die it didnt fired, i turned the key and the engine was spinning and it continued spinning the starter even if i release the key... i had to turn it off. tried twice and same result.


Then i disconnected the wires for the plugs and remove the first plug, and im trying to figure out where to disconnect the coil pack?

Im sorry, im pretty much a beginner for that, but i want to do it myself. I dont want to mess something up so i wanted to ask here first. Is just unpluging the 4 plugs wires enought?

Thx for any tips.


EDIT: nevermind i just understand now what Cmiller explained me... the coils are what i removed from the plugs already.... lol my poor english....

 

Well test is done, thx to Cmiller and chevycobaltss for the pointers.


Im not too sure about results, i used a timer to crank it for 3 seconds each time other wise results seemed to vary... on instruction it says 5 rev of engine but it was reading ridiculously low...

piston1: 170psi (2 test)
piston2: 165psi (2 test)
piston3: 165psi (2 test)
piston4: 165 psi , 2nd test 120psi but the engine was cranking slower..battery?... redid a test 3-4 minutes later got 150, then another at 158psi

Is it normal?

 

If you used a long hose on the comp tester it will take several comp strokes to reach peak reading. I think you are fine. If any were 130 or less after 5 comp strokes I'd be concerned.