Hi again JRV,
Very good to
Hi again JRV,
Very good topic here.
Regarding my issue - Mr. Foley has been a godsend here, has been helping me out immensely. To refresh, 328 spontaneously developed "popping" in idle and irregular surge in RPMs. No overall change in performance.
Parts changed to date include: plug wires/extenders/plugs/O-2 sensor/protection relay/fuel injectors/thermo-time switch/exhaust gaskets/this weekend all intake gaskets.
Items checked include: wiring harnesses & grounds, TDC&RPM sensors, fuel pressure, AAV, coolant tank thermostatic switch, alternator, CSI, intake & vacuum hose integrity. With the help of Mr. Foley have exchanged Jetronic & Microplex ECUs, coil units, and protection relays into his car...which ran like a top. We see (at my baseline mixture setting) similar values of 68% cold 72% warm and 74-76% hot. Swinging needle on my V/O O-2 sensor (plugged in) when running. O-2 sensor voltage at that point (baseline setting) 0.886mV. Except my car is symptomatic.
Don't think I'm forgetting anything above? Have striven not be thorough (smile). Next step I am thinking is to check that camshafts have not jumped a tooth - rear intake about 2-3mm from centerline of timing belt cover pointer.
My gastester CO mixture checker is not that impressive - does give a reading, but not sure it's trustworthy. So not much help here. Still have no access to exhaust gas analyzer.
Now interestingly when I twist mixture screw 1/4 turn rich duty cycle goes up (to 80-odd%) which seems strange. And improves, but does not eliminate popping sound & irregular idle. Disconnecting O-2 sensor (running open loop) makes my eyes water and again almost, but not quite, resolves syptoms. I have in my notes disconnected DC was 60%.
Very strange. If cams in alignment then will change caps/rotors (already cleaned x2). Suggestions from here? (smile)