fadiss2k

I was doing a compression test on my car today and decided to do a DIY for everybody!

You will need: Torque Wrech, 10mm socket, spark plug socket, socket extension, compression tester(about $25 from any auto store), allen wrech(not sure what size, its to take of the screws on the spark plug cover...i think M6)


Start the car and warm it up before beginning.

Turn off the car and remove the four screws holding the spark plug cover!


Then remove cover and unscrew the four bolts(10mm) holding the coils in place.


Unclip the clips that are on the coils.


Remove the four coils.


Now go remove the fuel pump fuse!


Remove all the spark plugs.


Screw on the tube that comes with the compression tester on the cylinder you want to test.


Then add the gauge.


Go inside the car and let it crank 8-9 times while pushing the gas pedal all the way to the floor.


Now go check the guage.


Release the pressure by pressing the button on the side of the tester.


I do this three times to get an average reading.(You dont have to if you dont want to)


Now write down that number for the cylinder.

Repeat for the next cylinder!
After you have done all four, you are almost done.
Put the spark plugs back into the motor.
Make sure all spark plugs are toqued correctly.
Spark plugs are torqued to 18ft/lbs.
Replace the coils. Connect the clips and make sure you hear a "CLICK" when putting them on.
Torque the coil bolts to 7 ft/lbs.
Replace your plug cover and screws.
Now go put the fuse back in!
You are now done!


Reading the results
People say 240 is what compression is supposed to be, but look more for consistancy than a higher number! If you get 220 215 218 220, then you are fine! Its not 240, but your numbers are all pretty close to 220 which means you are fine because you have pretty consistant numbers! But if you get 220 215 180 220 then you will know that there is something wrong in #3 bc it is a lot lower than the rest of them!

Hope this helps yall out!
Fadi

stphotographer

Awesome write up! I've always wondered how to do this Mods please sticky!

chillout18

Does it make a difference if you take out all the plugs at once.. I think thats what I did when I did my test

fadiss2k

I also heard it doesn't matter weather or not you pull one at a time or all at the same time. I didn't take them all out because i didn't clear my fuel line and didn't want the chance of fuel coming out when cranking. Personal choice i guess!

ATOice

Sweet post. Knowledge is everything.

fadiss2k

maybe it will get stickied on day! lol

jyeung528

did you get 200 and then 230 on the same cylinder???

i don't think it should deviate that much...even if it were on a difference cylinder.

fadiss2k

no, i got an average of 235 all across. 240 is the magic number you supposed to be looking for i think, but 235 is still good for an 8 year old car.
Thanks
Fadi

jyeung528

your 4 pictures show

200, 200, 235, and 230...???

mxt_77

Yes, you should remove all 4 when doing the test. It lowers the pressure in the cylinder, therefore decreasing the load on the battery.

Also, it helps ensure that you didn't forget to unplug one of the coils, which could lead to undesireable results (like the car trying to fire up during the test).