I just did a compression test on my 03 Ap1 S2K and all cylinders seem low. The motor has 95,000 miles on it and as long as I have owned it, it has never had a check engine light and low oil pressure. I use a magnetic drain plug and comes out with very little material. Valves were adjusted less than 1,000 miles ago. VETC pulls great and the car has never skipped a beat on the track. I did buy a cheap compression tester from amazon and when I did the test I let the car turn over around 8-9 times. Is it maybe the cheap tester or somethings else?

Cylinder Test 1 Test 2
1 181 180
2 182 181
3 176 175
4 190 191

 

The key is to get consistent results across all cylinders which you have. All testers are going to read differently, if you are not observing any issues, I think those results are fine.

 

Common issue with cheap compression tester to read low. Rent one from someplace like autozone, see what results you get.

Make sure batteey well charged

Make sure crank until gaige stops increasing

Make sure gauge not leaking at plug threads

Make sure fuel pump fuse pulled

Make sure throttle wide open all plugs removed

Make sure engine warm

Who did the valve adjust? How do you know was done right?

 

I did the valve adjustment. I used a proper valve adjustment tool, set intake to .008 and exhaust to .010 then checked clearances after a few hundred miles. I did not however keep throttle wide open during cranking must of missed that step somehow. Everything else you mentioned I did.

 

Have to be within 10% so looks to be fine

 

According to the Page 2-2 of the Service Manual nominal (approximate) compression pressure is 228psi BUT minimum compression is 135psi with a maximum variation between cylinders of 28psi (not "10%").

Yours are fine. Average of nominal and minimum pressures are -- wait for it! -- 181psi. Right what yours average.

-- Chuck

 

Yep thats about 10%

 

In what universe is 28psi 10% of 135psi? I'd have thought if Honda stated a variation of 10% was the limit they'd have stated that rather than a specific psi?

-- Chuck

 

If 135 on 1 cylinder and 168 on another = a problem and investigation needed with this engine and any other.
Maybe yours is,but would look at the issues

 

Probably a problem and not something I'd want -- but that's not the case here. I think the tolerance is due to the inaccuracy of the measuring equipment available outside of the factory.

-- Chuck