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2000 Civic LX automatic 196K miles, D16Y7 engine
Have been trouble shooting a CEL that gives misfire codes, sometimes one or two cylnders usually multiple or all. Recently did a compression test, with loaner tester from Auto Zone
Here are results #1 150, #2 160, #3 162, #4 165
According to the Shop Manual, in the specs section This is what I see
for D16Y5, D16Y6 and D16Y8
kPa (kgf/cm2, psi)
Minimum 930 (9.5, 135)
Maximum variation 200 (2.0, 28)
I'm going by the last number = psi
So according to the shop manual I am above the min and within the variation, my variation is 15

My question is this cyl 2-4 are within 3% but 1 is 10% less, is that significant for general purposes?
I'm thinking if the misfire was related to the compression difference it would only show as clyn 1 misfire and not the others. when the engine is running and I remove the ingn wires one by one, the engine changes as each one is removed and replaced

I just want to make sure if I should further investigate the within tolerances difference of cyln 1 or consider it normal and move on to other misfire trouble shooting?

for the rest of the trouble shooting Engine has 196K, I have replaced spark plugs, distributor, including the single coil within it (also rotor and cap) inspected IGN the wires (not the original) look OK, sprayed water over them in the dark, insulation seems OK, tested them for resistance seemed OK. Timing chain was replaced once by prev owner. Also under the heat shield a while ago did find crack in the exhaust manifold but does not seem to have spread open and no sign of exhaust noise

Next plan to look into valves, maybe sensors like O2, transmission (one of the codes generated was related to some type of transmission sensor) maybe fuel ignition.
Previously there was a idle fluctuation issue that seemed to have been fixed by cleaning the idler control valve in throttle body

Thanks for your attention
Bob

 
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Hey Bob,
For what it is worth, I also have a 1.6 Vtec SOHC (1999) and I did pull the head and found a blown head gasket. (I should have checked the compression before jumping into it.) I also found that it took almost 2 thousands off the head surface to level the head. Now I had almost 300K on my engine. I'm new to Honda so I don't think my inputs warrant much validity, but the variance between your cylinders could be slightly worn valves or worn rings or a combination of both. With only 196K on it your compression might be just ok. How's your power?

As far as misfires, I'm still learning. But in other makes of cars, replace the plugs, check the wires, check the cap and rotor and I hear that sometimes the distributor needs attention. Can you feel the misfire when driving or is it just the code showing up?

 
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Strick, thanks for the reply, excuse the late reply. As for your question about feeling the misfire, I don't so much notice anything driving, but sometimes it does idle rough.

Here we are several months later, so the CEL was still on, to update the situation I did a valve lash adjustment, just before that it had codes for multiple cylinder misfires. After the lash adjustment it did improve to only Cylinder 1 misfire. Eventually I did take it into a shop for Dx, actually two places. At first my regular place was closed so tried another place first. They both told me I had a Head Gasket problem. So now at this point I have the head off and the deck of the head and block have no indication of warpage. used a straight edge and .002 feeler gauge. Did a test for valve leakage, head turned upside down filled with water in cavity then blow air into exhaust and intake ports. here is the video of Cylnd 1 https://drive.google.com/file/d/17NV...ew?usp=sharing
I'm wondering if that leak is enough to cause a misfire

My question is I put the engine on TDC Cylnd 1 before disassembly. Now the head is off, and to test the other valves I will need to turn the Cam to close the valves. I assume as long as I return the cam gear to it's original position when I am done, things will be lined up again when I eventually put the head back on. From what I understand the bottom of the engine makes two turns for one turn of the cam.
Any comments or assistance is appreciated

Bob