checking compression w/ gauge

I know im supposed to have it at wide open throttle.... but would the injectors spray any fuel when im crankin the engine over? doesnt seem like it but ive never done it before and i just wanna make sure i do it right. So far my understanding is that i take out all the plugs (and number them according to cylinder) and remove all of the plug wires, screw in the gauge and have someone hold down the gas pedal and crank the engine over. anything else?

why would you hold the gas pedal down? just screw in the gauge and crank your engine over at least three times. then check the gauge write down your number and move to the next cylinder.


I believe that you want all cylinders to be within 20% of your highest pressure. in other words if 3 cylinders are 100 the fourth can be no lower than 80.

After you get your numbers. If you do have a bad cylinder put a few drops of oil in the cylinder and check it again. If the pressure is higher than it was before you have bad rings. If the pressure is still bad you need a valve job.

Yes you forgot something very important. You have to disable the fuel Injection by pulling out the fuse. Its labelled FI on on the fuse box, on my 2001 teg it the one on the top left corner. If you dont pull out the fuse and do a compression test you will flud the cylinders with gas and you may have to change your oil in order for your car to start again. Also when doing a compression test, make sure the engine is FULLY WARM, to get the most accurate results. Drive your car around for 5-10 minutes then do the test, but be carefull when taking out spark plugs on a warm engine since aluminum warps at high temp. Also remember to crank your engine fully about 7-10 times per cylinder and to have the gas and clutch pedal fully depressed to the ground. I recently did this on my gsr and i got 225psi per cylinder. With the engine completely cold i only got about 180psi, so make sure your engine is at operating temp.

i dunno it said on some instructions to make sure throttle is at WOT. i guess because if its closed then the cylinders are sucking out of somewhat of a vacuum...

it does need to be at WOT, it says so in the hanes and honda manual

wut about disabling the ignition?

the reason they say to keep it at WOT is because that essentially does the same job as disabling the injectors... as far as disabling the ignition all you have to do his disconnect the wiring connector that leads into the distributor.

theres no need to disable the ignition. for the fuel, just pull the FI fuse like stated before. also it wont really matter too much if the Engine is at WOT. it will only change the compression a little bit. the main thing u need to look for is that all the cylinders have somewhat the same compression. and if it's a GSR, i think the helms manual said that it should be abour 270 psi. u might have to double check that