IonNinja

So recently I ran a compression test on my motor and pulled ~120s across the board. Each cylinder pulled within the allowed percentage but the numbers seem a little low.

I can't seem to find any solid information on compression tests on these motors. Should I be looking at a rebuild or what? Who else has run a compression test on a stock 2.2 and what numbers did you pull?

The car seems to run/idle fine but is lacking alot of power.

*car felt this way pre-blower btw

Cobaltsky05

it's lacking a lot of power since the eaton? you should run a tactrix cable and log it. See what, where, and when it's noticeable. what map sensor are you running? I have my oem map and oem 2.2 maf and since the eaton build I have broke 2 axles, LSD in my trans came through the case, and also a clutch. Not in that order... right now I am looking for a trans.

ShortStack

Perfect is 200.

150-160 is workable.

Gene Culley

iTrader: (1)

Here is the listing in the service manual.

Engine Compression Test
•Charge the battery if the battery is not fully charged.
•Disable the ignition system.
•Disable the fuel injection system.
•Remove all spark plugs.
•Turn the ignition to the ON position.
•Depress the accelerator pedal to position the throttle plate wide open.
•Start with the compression gauge at zero and crank the engine through 4 compression strokes, 4 puffs.
•Measure the compression for each cylinder. Record the readings.
•If a cylinder has low compression, inject approximately 15 ml (1 tablespoon) of engine oil into the combustion chamber through the spark plug hole. Measure the compression again and record the reading.
•The minimum compression in any 1 cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any 1 cylinder is 1 035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1 035 x 70% = 725) (150 x 70% = 105).
• Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.

• Piston Rings Leaking -- Compression is low on the first stroke. Compression builds up with the following strokes, but does not reach normal. Compression improves considerably when you add oil.

• Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.

• If 2 adjacent cylinders have lower than normal compression, and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders.

IonNinja

alright i'll have to go back and run a wet compression test

im thinkin valve problem so far...hmm

NWAE Cobalt

iTrader: (1)

i would think rings first...unless you bent a valve...

how high are you reving out??

mrsilent13

well looks like im good then at 150 175 150 175. i just did my compression about a week ago
but right now i have an issue...its burning oil like no other....so im thinking that my valve guides are fucked. is there any other explanation for me to be burning about a quart in about 2 days total drive time about 2 hours in the city.....so either my head cracked or the seals are just fucked...i guess its time to rip it open again and see what the **** is up...if anything ill just replace the head

HunterKiller89

iTrader: (1)

^^^i always figured your turbo was eatin it.... or bad seals on your piston rings... its definitely giving you some bad blue smoke when you floor it

mrsilent13

the blue smoke you saw that time was cuz i had a leaky head gasket...but im got a cometic and that fixed that problem and now my turbo blew up and looks like the head is craked or i have really bad valve guides...its not piston rings because they dont leak at all...they hold a constant pressure

HunterKiller89

iTrader: (1)

gotcha. well then, take trhat head off and make some inspection time..lol

mrsilent13

i actually just acquired a good used head...my friend is dropping it off at my wifes work as we speak....so i should have it here tonight around 6....this way i can take the fucked head off and get it fixed or watever and still have a working car

HunterKiller89

iTrader: (1)

well, if u get ur stock head fixed, and have that used head...ill buy it off you. I need a core to send in to get ported.

mrsilent13

ill hook it up once im done with it....

Cobaltsky05

Gene had some great info! can you post the all of the service manuals! that would be just swell.... except there's what 3 books of 300+ pages?

ryansalazan

iTrader: (6)

so if your compression is low how do you step it up to as close as perfect as possible besides buying new pistons and a head lol

mrsilent13

if your compression is low...its because your rings are leaking...so you need new rings...and you need to bore the cylinder walls in order for the new rings to sit right

randizzle

not always the case. there are plenty other reasons for low compression. valves, head, and head gasket are a few that come off the top of my head.

mrsilent13

yes you are right i guess i forgot a few...the best way to figuere out where you are leaking is to do a leak down test....pull the spark plugs out and then close all the valves to that cylinder and install your leak down test valve where your spark plug goes and blow some air in there and listen to see where the air is going out....pull your dipstick out as well....if you hear air going out your intake...your intake valves are leaking...if you hear air through your exhaust its the exhaust valves that are leaking...and if you hear air coming out your dip stick...the rings are leaking...and this is the easiest way to diagnose your problem...if you hear air coming out another cylinder then your head gasket is fucked

NWAE Cobalt

iTrader: (1)

very much correct, easy way to rule out the rings though...wet compression test...90% of time it will give you a yay/nay answer on that...then all you have to worry about is valves or head gasket, either way you HAVE to pull the head to fix it so get it off and inspect after

Cobaltsky05

just curious what's a wet compression test? vs a dry test?

mrsilent13

a wet test is when when you pour a small amount of oil in the cylinder to help seal up the rings a little bit...small amount is like a spoon full of oil...not alot...and if compression goes up...rings are ok...and a dry test is just that...a dry test

NWAE Cobalt

iTrader: (1)

close, if compression goes up then rings are NOT ok

mrsilent13

dayam...i always **** that one up...its all good...thanks