Our '05 Liberty has a whopping 36k miles on it. It's all stock except a K&N air filter element that's been in there for 4 years. Last year we started occasionally getting P0304 (misfire cylinder #4), usually only after driving 40 miles or more at a time. It never happened on shorter drives. It was a couple thousand miles overdue for spark plugs, so they were replaced with NGK ZFR6FGP. No difference. I swapped #4 coil with #2. No difference. Sometimes we thought we detected a slightly rough idle about the time the error occurred, sometimes not.
Now this poor Liberty had been sitting unused a lot, and the fuel in the tank wasn't very fresh. We started driving it more frequently and added a can of Berryman's B12 to each of the next 2 tanks of fuel. The codes occurred less frequently and eventually stopped for several months. Today, after driving 50 miles, P0304 and P0430(Catalyst System Efficiency Below Threshold (Bank 2)) showed up at the same time. Again, we thought we briefly noticed a rough idle.
Because P0304 stayed away after running fresh fuel + cleaner though it, I thought the problem might be a dirty #4 injector. I also wonder if the P0430 code could be related. Any thoughts?
Martin
Now this poor Liberty had been sitting unused a lot, and the fuel in the tank wasn't very fresh. We started driving it more frequently and added a can of Berryman's B12 to each of the next 2 tanks of fuel. The codes occurred less frequently and eventually stopped for several months. Today, after driving 50 miles, P0304 and P0430(Catalyst System Efficiency Below Threshold (Bank 2)) showed up at the same time. Again, we thought we briefly noticed a rough idle.
Because P0304 stayed away after running fresh fuel + cleaner though it, I thought the problem might be a dirty #4 injector. I also wonder if the P0430 code could be related. Any thoughts?
Martin
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