So I've done some testing.
Plug # 1 definitely dead as it reads open circuit on the meter, and plugs are definitely rated at 4.4 volts.
I tested the glow voltage on plug 4. Turn key on and it's reading full voltage (pegs out on 2.5 volt scale on analog meter) for about a second, then it drops to a constant 0.5 volts for as long as I had the key on. This seems a very low glow period, maybe a dodgy GP module?
I pulled a plug to test glow. The plug definitely got hot. Not red hot, but hot enough to leave a burn on my finger like I'd grabbed a soldering iron tip!
Now, here's the curious part - oily residue on the plug before the first glow attempt. Haven't run the Jeep today but it had a good 30 km run yesterday. This residue all but burnt off while glowing. Pic of this attached. Would this be leaking injectors? After it sits cold overnight she takes ages to fire, and sometimes several cranking events. When she finally fires there's a plume of white smoke out back. Never a problem starting in the arvo if it's driven in the morning and then started again in the evening, but the cold morning starts are always difficult. Never a problem in warm weather either, last year's winter FNQ trip vindicated this.
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