I have a 1999 Civic Ex with a D16Y8 V-Tec and a 5 speed manual. It just lacks a bit of power (ALL the time) and has a slight and irregular miss under heavy load and at mid engine RPM. It has new plugs (NGK platinum), new NGK high tension wires, new distributor cap and rotor, new PCV valve, new air filter. I have cleaned the idle air control valve (it WAS pretty clean), cleaned the throttle body (with the special cleaner) set the valves, set the timing (it was right on) tried swapping in a known good MAP sensor. It is NOT a disabling condition. The car always starts and has never stalled or let me down (YET anyway). The timing belt has under 30,000 kilometers on it. Temperature guage is always the same (doesn't overheat), and does operate at 'normal' temperature. The tachometer is 'stable' and isn't jumping around - ever. Fuel supply seems adequate (car will go 160 km/h or about 100 miles per hour) easily. So - interesting, eh?? (that is just so Canadian). Thanks to anyone for any help.

 

Any CEL codes?

Have you checked the ignition timing with a timing gun?

Has the fuel filter been replaced?

Does the problem only happen after the engine is hot or does a cold engine also do it?

Have you tried a Seafoam treatment?

 

Check your compression if you checked everything like you said in your post i would deff do that. its possibly bad rings......How many miles on the motor?

 

I replaced the ignition coil (it was outside specs), and the ICM while I was in there, and reset the timing. Seems a bit better. It has NO codes, and compression is about 135 to 140. I am thinking about going back to regular NGK plugs instead of the platinum plugs I installed just a few thousand kilometers ago.