Hi all,
We have a 1991 manual Honda Civic DX hatchback (base model, no power steering, no A/C) that has been in the family for many years, its now done 320,000 miles, been stolen 3 times and recovered. It recently passed from my daughter to my son, he loves it because its economical and he can fit a double bass in it. It still runs as sweet as ever no smoke and idle seems good.
Sadly it just failed its California smog test, reputedly on high HC emissions at idle. My son has fitted new air cleaner, overhauled the ignition system (distributer cap and rotor were in poor shape - replaced) checked spark plug gaps etc. The spark plugs look fine all about the same color (approved brown, just like the pics).
My immediate reaction was EGR valve but we don't think it has one (only on automatics in California apparently), we are wondering where to look next, I have a compression tester on order and will be looking at that next week.
Assuming the compression test is OK where would be a good place to start? IACV valve? PCV valve? Catalytic converter? (its Pre-OBD2)

Any suggestions are most welcome,
Geoff