Going to do a compression test on my 2001 wrx tomorrow while changing the plugs what numbers should i be looking for will be doing on a cold engine which I know isn't ideal but I'm suffering with a bad back (violins playing) so will take me over an hour to strip it (no exaggeration) any help will be appreciated thanks in advance.

Compression pressure should be between 142 and 171 and no more than 10 psi difference between all 4 

Is that on a cold engine

 

126 across the board on cold engine how much trouble am I in 

that way to low i get about 150 on cold 

 

That's what I thought leak down test next to try and pinpoint the issue worst thing is engine has less than a 1000 miles on it 

I know this is a long shot but could valve clearance cause low compression (i know I'm probably clutching at straws)

i'd be more worried about any readings between them. but 126 across the board is fine on a cold engine

Thanks for the reply tidgy i 're tested them using a compression tester today with a cap of oil in each cylinder and no change (heard it was meant to increase pressure if it were rings but didn't change) the other concerning thing is it takes at atleas t 7 cranks to build 126psi

If your worried then i'd pop it down to a specialist and get them to have a look. given the results i wouldnt be too worried myself

Thanks again for the reply gonna have a leak down test performed and will update when completed