Why would i3 extended not be on that list? Marginal electric range (especially when cold). Limp mode while on gas engine. Ridiculously short range on gas. When someone asks about PHEV done poorly, that one is near the top of my list.
The misfire could annoy the O2 sensor. I would use the car in gas mode for a bit to give it a run and get some fuel through it. If you still have problems after a few tanks proceed with further diagnostic work (assuming the misfire is occasional and not under load, you don't want to burn up your cat).
What about the O2 sensor? It's doesn't often register as failed unless it's failed, and it would cause the misfires.
I thought about this a bit and I remembered this same issue with my buddy's Mini and my neighbour's Audi.
After ruling out plugs and coils it was actually carboned-up intake valves.
Im not sure if the Volt is susceptible to that but something to check.
I once got a lean bank/ misfiring code after an oil change and air filter swap. After much head scratching I realized the "tech had put the MAF in backwards, the airflow arrow was pointing the wrong direction. Flipped it around and it ran fine.O2 sensor has been replaced. That fault code is now gone.
So it ran fine absolutely perfect when I had the AIH removed from on top of the motor and it was pulling air right into the TB. I let it run for a good 20-30 mins and not a single hiccup.
Bolted the AIH, snorkels and airbox back on, and the miss came back.
Disconnected the upper airbox from the lower (bypass the air filter) no change.
Disconnected the intake snorkel from the upper airbox (bypass the MAF sensor) and the idle smoothed our right away.
Switched between these setups and the consistent result was that when intake air is being pulled past the MAF sensor there is a miss.
Tried cleaning the MAF sensor but saw no change. I know that a faulty or dirty MAF sensor can cause idle issues. Process of elimination makes me think the MAF sensor is faulty but I’m not getting any codes directly related to it.
I once got a lean bank/ misfiring code after an oil change and air filter swap. After much head scratching I realized the "tech had put the MAF in backwards, the airflow arrow was pointing the wrong direction. Flipped it around and it ran fine.
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