I am pretty sure i did this right. i did the test on an 06 wrx engine in my 98 impreza. the car hasnt been running for some reason and someone helping me out gave me the idea to do a compression test. just to make sure, i tested the compression tester on a pair of dirt bikes and it worked perfectly

here are my numbers:

1: 25psi
2: 50psi
3: 24 psi
4: 50 psi

now if this is right its both good and bad, good; i know what the problem is, bad; its going to cost me

however, im not 100% that i did it right. is there any trick to doing a compression test on a drive by wire car like the 06 wrx?

 

IIRC, 150psi is about where you want to be. So either you've got serious issues on both sides of the engine or the test was not performed properly.

 

Yes, those numbers are totally off, you must not have done the test right. A difference of even 2 PSI between cylinders can mean serious trouble, and you are missing 100psi of pressure even in your best test and have gaps of 25psi or more.

 

Meilers can you even read with a 2PSI accuracy on any compression tester? I usually measure to the nearest 5PSI

As long as all cylinders are within 10% difference from each other all is fine.

Salvator, All you need to remember to do when performing a compression test is to take all the spark plugs out while testing and also to disconnect all the fuel injector connectors so they're not squirting fuel while you're cranking the engine.

I usually do the test as soon as the engine has cooled down enough to play with as the cylinder walls still have some oil on them to give repeatable numbers. Doing the test cold can give misleading figures as the piston rings may not seal well.

Let us know how you went

 

tried a better compression tester, but got the same results.

the engine hasn't started in awhile and checking the compression was an idea to see if it might be a mechanical problem. I was told that my problem (no ground to injectors or ignition coils) could be mechanical, if something is wrong, the ecu won't allow the car to run. checking the compression is supposed to be an easy way to check to see what might be wrong

 

hmm...

maybe its ur gauge...

 

^ he already said he tried another gauge.

did you over-rev the engine at one point? You may have fuunked damn near all your valves, have you done a leak down yet?

Also, post your procedure or a link to the page you used for instructions on doing your test.

 

oh.. sorry

 

If your doing the test right. Suby nooby is right and you probably have messed up valves.

 

did you do the test while pushing the throttle down. you'll need somone to either read the tester while you push down on the gas or you read the tester while someone pushes on the gas. either that or use a nice digital gauge that will record the data.

 

some mechanical ones will keep pushing the needle farther and not go back to 0 until you click a button, pretty cool stuff.

 

Do a leak down test if you can like SubyNooby sugested, this will tell you where the compressed air is going. Not sure if you have access to this equipment or can rig something up?

If not... as crazy as it sounds I think you might get away with sticking a vacuum cleaner onto your exhaust pipe while holding a burning incense stick (Nag-Chumpa should work best) next each of the open spark plug holes, then do the same by sticking the vacuum on the intake (throttle pushed in). A brick on the throttle pedal might be the go to avoid witnesses if you know what I mean.

Anyway this will give you a rough idea of whether the intake or exhaust valves are buggered on each cylinder. If neither the exhaust or intake vacuuming sucks smoke into the cylinders then your piston rings might be the culprit (sucking on the oil fill tube might verify this hehehe).

Desperate times call for drastic measures Post pics of vacuum/incense in action

Edit: you'll have to manually rotate the crank until the cylinder under test is at TDC just before its power stroke so that its valves are closed. Good luck

Edit2: Also block off the intake while while sucking on the exhaust pipe and vise versa, otherwise you'll lose all the vacuum through these as other cylinder's valves will be open. This is gettn crazier and crazier