compression test !!!

[ralpher]

i just did a compression test and all 4 were around 90-110 psi
i dont think that is good ???

[MR2Jedi]

Don't about the JDM 3sgte, but that would be very low for a USDM 3sgte. Check the specs.

[TheEngineer]

The normal compression is 164 and the service limit is 128psi with a 14psi difference in cylinders for a USDM 3SGTE. A JDM Engine is just about the same, maybe a bit higher. Are you sure you let it crank enough times for the compression to build up in the meter? IMO as long as they are all close then i ussually dont call it a problem because it may just be a poorly calibrated meter. But if you get a cylinder off by 20psi you may want to look into it.

First off though we need the real numbers for each cylinder. And if you find one that is low by like 20psi then put about a cap full of oil into the cylinder and let sit for a few minutes then re-do the test and see if the number jumps at all.

[toyotaspeed90]

How long as the engine sat?

Did you put anything down the cylinders if the engine hasn't started in a very long time?

How did you crank the engine to get your results (ie, is it in the car and did it with a starter or not)

did you do it warm?

did you hold the TB open when you did your test?

etc.

[ralpher]

the engine didnt sit at all
iv been driving it for the last week and it worked fine untill now

i cranked the engine with the key

it was warm

and no i didnt hold it open

[ralpher]

two cylinders were 90 one was 98 and one was 110 , im gonna do it again tomorrow to make sure.
someone tell me how to do it right please

does it sound like a head gasket so far ??

[TheEngineer]

Its pretty hard to mess up but you need someone to tell you when to stop cranking. Basically you should see the needle continue to go up each time until it finally equals out the cylinder pressure. As soon as it sustains the same pressure through a couple revolutions you can stop.

Also if you have a weak battery you will get lower numbers. so make sure your battery is fully charged.

[toyotaspeed90]

I generally listen to the number of starter/engine cranks.. usually let it go for about 7 rounds, and then make sure it's the same for every cylinder.

hold the throttle down 100% to allow air to move in and out, do it when it's warm

a 10-15% variance generally means that there is a problem

[ralpher]

should i keep the other 3 spark plugs in while i do it ??
or take them all out and do it ?

[TheEngineer]

take them all out. And also pull the fuel pump fuse....otherwise youll have a mess

[ralpher]

i did it right this time haha

#1) 175
#2) 172
#3) 165
#4) 176

[TheEngineer]

MMmmmm much better. Nothing wrong with those numbers