Q: Idle random misfire, very light but not passing smog

asked by on September 29, 2016

I had just done a head gasket job and started up great ran it for a bit and got misfire code and variable valve timing code and knock sensor #2 on snap on tool. tried to pass smog and it passed 25mph test but failed idle HC:263 , CO: .02% , Co2: 7.4% , O2: 10.0% , NO ppm: 32

i have smoke tested before those numbers and fixed all leaks but still cant find anything if someone could push me in the right direction because 3 other mechanics have taken my money and left me in the same spot. i have replaced o2 sensor, checked coil ohm readings, new spark plugs, new oil, valve seats are good, compression 180 across the board, pistons looked great with no wear during rebuild, camshaft position sensor, fuel filter, fuel pump pressure at 50psi on 3.5 bar system, only thing i could think of maybe injectors or coolant temp sensor but i have obd1 system so am having a hard time without a snap on scanner please help.... Robert

My car has 200000 miles.
My car has a manual transmission.

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