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Discussion Starter #1
My first engine was replaced at 109k miles with this new factory engine. At 176k miles the check engine light came on for a #2 cylinder misfire. The light goes on and off. With fuel additives (b12 Chemtool, Seafoam, upper cylinder lubricant) and 93 octane gas, the light will turn off.

My cel for #2 cylinder misfire usually kicks on at idle, but occasionally while driving. The engine starts to run rough and then I know its only a few minutes before the cel goes on. In a dry climate it idles smooth--California 75 degrees. It appears to be related to high humidity. It first came on in New Jersey during dripping humidity, fog and drizzle, and went off two days later when it got to 85 degrees and low humidity.

It came on last week at 71 degrees and intense humidity here in Dallas. The idle also gets worse with the a/c running, but when the cel came on last week, the a/c was not on.

I can get the cel to turn off. This week with 20 gallons of 87 octane in the tank from Pilot, the cel was on. I added two cans of B12 Chemtool fuel additives and one small bottle of STP upper cylinder lubricant. Then I added 2.5 gallons of Valero 93 octane gas. When I started up right after refueling, the light was off. The light is off for now, but the engine still has a slight hiccup. I'm expecting the cel when the humidity goes back up.

The cel goes on and turns off. It's like a little engine grimlin is in there making it happen. The dealers in Dallas are all backed up with engine related repairs so I'd have to leave my truck a week before its looked at.

Possible causes (im not a mechanic so I can only describe some causes). PLEASE MAKE SUGGESTIONS

1. Clogged fuel injector.
2. Malfunctioning fuel injector.
3. Loose or defective sensor that determines fuel injection amount.
4. Loose or defective wire that controls amount of fuel/air into cylinder.
5. Fouled spark plug.
6. A crack somewhere that is letting in moisture to the combustion chamber.

If you have experience troubleshooting or repairing this engine, please offer suggestions. The Chrysler technicians couldn't identify the #5misfire cause on the last engine, but this is different because the cel doesn't stay on.
 

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Bad spark plug, bad cylinder coil will both be worse during high humidity. Change them first as both are cheap. Are you saying the complete engine, heads, and injection system was changed out about 65 K miles ago? The fuel injector can be pulled and tested fairly easily on most engines. I don't know the Pentastar engine specifically.
 

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My first engine was replaced at 109k miles with this new factory engine. At 176k miles the check engine light came on for a #2 cylinder misfire.
PLEASE MAKE SUGGESTION
My suggestion is to sell and go with the 3.0L diesel. Good luck.

I'm researching a Pro as a van conversion. I've followed your engine difficulty history. Your use may be difficult for the car based 3.6L to handle. It has an aluminum block, a cast iron crankshaft and all the same dimension bearings and standard rods. The 3.0L diesel has an iron block, forged steel crankshaft and rods with the necessary selected individual bearings those forged parts require. Forged engine parts and a cast iron block will provide the added strength for true commercial duty and longevity. Incidentally, the Transit 3.0L diesel is being supplied with a cast iron crank by Ford. Forging after machining slightly changes the dimensions and each bearing must be individually fitted by a skilled technician at a higher cost to the manufacturer.
But those parts are why Subaru and Honda high revving 4 cylinder engines last for 250k miles compared to 100k for a US version.
 

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Discussion Starter #4
Engine has not thrown a cel in over a month. It can't be a block or cylinder issue, so i suspect electrical (harness, connector) or the injector.
 

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Plug and/or coil would be my first thought. Then injector....
 
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