I borrowed a compression tester from a friend for the heck of it so I could test my car. I pulled the fuel pump fuse, the plug wires, and the spark plugs. Hooked up the gauge and got the following results:

Cyl 1 - 225
Cyl 2 - 225
Cyl 3 - 225
Cyl 4 - 160, 70, 80, 90, 90

The car is a '00 civic si with 43k miles. Only mods at this point are i/h/e/ecu. The car is a daily driver that's been used for a few track days and it's been to the drag strip 10-15 times. I drive the car hard, but it's never abused. The car doesn't burn oil between changes, doesn't puff smoke, and has never felt down on power.

Any ideas on the low compression? I'm going to see if I can do a leak down test sometime this week. I'm getting ready to throw in some CTR cams ... looks like I might be doing a bottom end build-up sooner than expected.

 

fried the piston rings maybe i :dunno: buthtats pretty odd for a 00' Si though:thinking:

 

That was my first thought too, but since there's no blue smoke coming out of the exhaust, I didn't think it was the rings. :dunno:

All the plugs looked good too, so I'm really at a loss.

 

Test one of the "good" cylinders again to make sure that the schrader valve on your compression tester didn't get stuck open...

 

Thanks. Tested Cyl #1 two times. Got 225 and 220. I guess I could try another gauge and see what happens.

 

My point was that assuming you tested cylinder 4 last, you could have gotten good readings for cylinder 1-3 and a leaky gauge (or stuck check valve) on #4, that's why I'm saying to go back and test 1,2 or 3 again to see if you get the same numbers as before.

 

I guess I should have clarified. I got 225 on cyl 1, 2, and 3. Then I tested cyl 4 multiple times. After that I went back to cyl 1 to retest to make sure the gauge was working. I got 220 that time ... so I think that shows the gauge is working correctly.

 

Ok, you and I have the exact same thought pattern...oh well, too bad about cyl 4

 

So I did my original test with the engine cold ... which I've learned was incorrect. I did a re-test again tonight at normal operating temps. Results were as follows:

cyl #1 - 230
cyl #2 - 230
cyl #3 - 230
cyl #4 - 230

Looks like everything is normal. *shrug* Anyone who reads this, learn from my mistake ... do your compression test with a warm engine. Thanks to those of you that offered advice.

 

hahaha... man you were worried for nothing. That sucks.

Glad it worked out.