ok so later today im going to do a compression test on my 98 ls motor cuz it sounds like a subaru and i just want to know a few things
1. what psi should i be looking for
2. what do i have to do exactly do i have to remove a fuse or something so the car doesnt get gas while i do the test or do i do it with the injectors still running??


please a lil bit of help on this would be appreciated

Thanks
~~Jeff

 

Remove spark plugs, thats it...

I would say 190-220 (estimate) did mines a while back, not too sure on the numbers...

 

- remove spark plugs and ecu fuse
- make sure throttle is wide open
- crank engine for a few seconds
- make sure engine is up to operating temps first

the actual numbers arent as important as their variance from one another. they shouldnt be more than 10-15psi apart.

 

unplug dizzy,
if your obd1 unplug ecu fuse,
have it wot when car is at operating temp,
have all plugs out when doing test

good luck, if one is lower than the rest add a capful of oil and if the compression goes up its your rings, if it stays about the same its your valves

look for between 180-200 as long as they're within 10% of each other your good to go

 

Whoa, well we did it to a 2000 Civic Si, we just did that...

So you guys corrected me...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doood &raquo;</TD></TR><TR><TD CLASS="quote">- remove spark plugs and ecu fuse
- make sure throttle is wide open
- crank engine for a few seconds
- make sure engine is up to operating temps first

the actual numbers arent as important as their variance from one another. they shouldnt be more than 10-15psi apart.</TD></TR></TABLE>

everythings right except the engine shouldnt be warm.. that will minimize and problems your engine has while if its cold any problems will be obvious through the compression test.

and for the oil leak down where you squirt some oil to diagnose where in the engine there is worn part... u just squirt a little bit of oil. then do another compression test on whatever cylinder(s) your checking.... if the psi goes up it means you have worn rings or cylinder walls or both... if it is still the same readin then your problem can be one/all/combination of the following:warpage, head gasket, or anything valve related.

a leak down compression test along with a stethoscope will also help you locate where the problem is without taking the engine appart.

 

(nominal= good)
(minimum= anything below this and you need to start worrying)
(max var: maximum variation between cylinders. ie Cyl 1=190, cyl 2=150, you have a problem)

Gen 1
86-89 d16a1
nominal: 192 psi
minimum: 134 psi
max var: 28 psi

Gen 2
90-91 b18a
nominal 185 psi
minimum: 135 psi
max var: 28 psi

92-93 b18a1
nominal: 199 psi
minimum: 135 psi
max var: 28 psi

92-93 b17a
nominal: 199 psi
minimum: 135 psi
max var: 28 psi

gen 3
94-01 b18b1
nominal: 199 psi
minimum: 135 psi
max var: 28 psi

94-01 b18c1
nominal: 270 psi
minimum: 135 psi
max var: 28 psi

97-01 b18c5
nominal: 270 psi
minimum: 135 psi
max var: 28 psi

gen 4
02+ k20a3
nominal: (?)
minimum: 135 psi
max var: 28 psi

02+ k20a2
nominal: (?)
minimum: 135 psi
max var: 28 psi

 

just to update all you guys that helped me out i finally got a compression tester from a good friend and i did the test today when i got out of work around 1130pm the results are.............................


1st cyl. 200, 2nd cyl. 200, 3rd cyl. 195, 4th cyl. (problem cylinder) 60!! so i did a small leak down test and no change in the pressure which im kinda happy about cuz at least i dont need pistons, but im getting a new head, headgasket, valves, cams, cam gears, and valve cover gasket. so im doin all this work this weekend. im buying the gaskets and head tomorrow and doing the work saturday will post up how it goes