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Hello! New to the forum. I’ve been reading all the posts on idle issues and can’t seem to figure out mine. 2002 Honda Civic Ex auto transmission. I got a check engine light for po303 cylinder 3 misfire. I replace all the spark plugs with NGK spark plugs and verified they were gapped correctly. Issue still persisted, so I started to pull ignition coils while the car was running. All coils cause rpm change when unplugged expect cylinder 3. So I replaced the ignition coils with OEM.

after changing spark plugs and coils, I don’t get a CEL but still feel a misfire, especially at idle and while stopped at lights. So I cleaned the Egr valve and intake manifold passageways as well as install a new intake manifold gasket. The car still feels like it’s missing at stops, idles around 500 and the car shakes.

also I don’t believe the head gasket is blown as the car never overheats, and I’m not losing any coolant, or seeing smoke from tailpipe.

any ideas and tips would be greatly appreciated!

 
Rep Power: 224

According to the service manual idle should be 720 +/- 50 RPM at warm idle with no electrical load. 500 is a bit low and could cause some vibration.

 
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Update!

i cleaned all the injectors today and the car seems to be running a lot better! If anything changes I’ll update.