I have a 1998 Honda Civic LX, 1.6L SOHC engine. It has appox. 173,500 miles on it. For the past month cylinder 2 has been misfiring. I have changed the plugs, wires, rotor, and distributor cap. I also removed the fuel injectors and hand cleaned them, and removed the coil pack and had Auto Zone test it. the coil pack tested good, but was borderline on the primary. The cylinder only misfires after the car has warmed up, and shakes when stopped at a stoplight. I cleared the OBII codes and flushed the coolant system. While flushing the system, the car didn't misfire. Now the new coolant is back in and the car is misfiring again, when the engine is warm. I took a look at the exhaust manifold, and there is a crack in the middle that goes from the O2 sensor to the top of the manifold. Could this be the cause, or is there something that I'm missing? Any suggestions would help. And thanks in advance.

 

Don't rule out the distributor, itself or crankshaft position sensor.

 

Check valve adjustment. Or just loosen the valves on #2 some and see if that helps.

Swap #2 injector with one of the other ones and see if problem moves to that cylinder. I suggest swapping with #3 since it is 180 degrees away from #2 in the firing order.

 

I adjusted the valves and swapped the injectors, still misfiring. Another thing I missed was when the electrical plug is pulled from the injector on cylinder 2, the engine doesn't stumble. As where 1, 3, and 4 do. Checked the current going through wire on 2 and it matches up with all the other wires.

 

The cracked manifold isn't helping, but I don't think that would be so cylinder specific. I'd do a compression test next. Test all cylinders first with the engine cold and then with it warmed up. Be sure to unplug the power wire to the distributor during a compression test so the coil does not fire into open circuit.

 

Did a compression test and 1,3,4 tested between 120-125 cylinder 2 tested at 95. Do you think it might be a bad exhaust valve? Also, when adjusting cylinders the adjusting screw on cylinder 1 is stuck (can't tighten or loosen)...tried some PB Buster but didn't help. Any suggestions for that? I appreciate the help!

 

I cylinder 1 in spec? May never be an issue...unless you brake it trying to fix what isn't broken. How are the clearances on cylinder 2?

 

Do another compression test for all cylinders. Then squirt a little engine oil into #2 cylinder and do compression check. If the number improves #2 has an issue with piston rings and/or barrel.

 

Re-tested and #2 was at 60psi. Put a squirt of oil in and still came out to be 60psi . My dad thinks it might be a bad valve? Does that sound correct or is there something else? Thanks for all the help guys.

 

If the pressure on #2 stayed the same after putting oil, it is more than likely valve issue. There is a Honda service bulletin in regards to valve issue. The number I have for the bulletin is 85-007. There might be newer number on this subject.

This is what I would do if it was my car. Make sure valve clearances are within spec first and do the bulletin. See if you can improve on compression numbers.

If the car is drivable, I would also try using valve lube additive in the oil. I do not have personal experience using the stuff but if it works,,,,,.