whats up...i just did a compression test on my engine ...im using a 95 gsr motor with a drag 3 kit in a 95 hatch the motor has about 70k on it ..i also forgot to pump the gas while i was doing it. anyway the numbers where
cylinder#1...200
cylinder#2...180
cylinder#3...190
cylinder#4...195

anyway are these numbers fine or are they bad...the engine was at normal operating temp... i pulled the ecu plug but i FORGOT to push the gas pedal to full throttle would that effect the numbers...thanks alot let me know

 

You really can't just numbers that are done wrong because they are obviously wrong. Keep the gas floored the whole time while you're doing it, and post the right #'s.

 

it doesnt matter if its floored or not. as long as the test is done the same way between all 4 cylinders. your numbers are ok.

 

Wide Open Throttle is actually the "right" way to do it. Butt...those number look good so why argue. If they were all low then ya, maybe do it WOT and see if your numbesr are higher. concistancy is important..true, true your motor is fine

 

do you pull all the spark plugs at once, or keep the ones in you're not doing? Cuz i got some outragously high numbers for my D. Like in the 200 psi range. pulled the ecu fuse and then at WOT cranked it over 8 times. Are you supposed to crank it over 8 seperate times individually or let it crank over 8 times in a row (not letting off the ignition.) thanks

 

heheheheheheh, long night sorry guys anyways...uh.....yeah.... CHEERS!


[Modified by GRCuadros, 2:31 AM 3/1/2003]

 

The way I understand it you crank it 8 times with out stopping. You can audibly tell that it has cranked so counting is easy. When I put my hood up I can set the gauge in the valve cover and watch it through the crack between the hood and the body. I usually experience full compression after 7 cranks (it doesn't get any higher) but do 8 for good measure. I believe all spark plugs should be out and pull the fuel injection fuse so you don't get tons of raw fuel in the cylinder. I have done it with and without WOT and the numbers were exactly the same. Leaving the fuel injection fuse in didn't change anything either, just got lots of gas in there. I was getting 160 psi on my b18c and buring oil like crazy so I just replaced my rings today. What a job. Hopefully all will be well now

 

Yah it is.

Although you're probably not going to notice more than a 5 psi difference when holding the peddle down.

 

exactly. It's no big deal but a good habit to get into.

 

Stop cranking when the needle pegs out at its highest reading. WOT helps.

 

do a running compression test. remove only one spark plug at a time and place compression tester in spark plug hole. start the car and let it run. keep pushing the shrader valve to reset the readings and do it several times until you see a good average. this method indicates how the motor runs in conjunction with one another.

 

that is not the normal procedure! so you run the car on 3cyl !! that can't be good. What do you do with the one ingition wire?? what about the fuel washing the walls in the one cyl you are testing? unplug the injector? I think i'll stick to the procedure in the manuels. intersing idea though

 

You shouldn't do that.

 

cyl2 looks low
get a leakdown test done.

 

Just a couple thoughts...

Why aren't you worried about gas washing the cylinder walls with the 'normal' method? You should unplug injectors anyway, or pull your fuel pump fuse.

If your engine runs at different rpm with each plug out, then your compression pressures can't be compared against each other. The whole idea of using the starter is that no matter which one you are measuring, the engine's spinning the same speed. The only advantage I can think of for a running compression test is that its spinning faster.