Hello, I have a 2002 Dodge Durango Sport with a 4.7 Magnum engine. I have gotten the dreaded P0300 code along with P0301 and P0308 as well. The truck runs beautiful for the first 10-20 minutes of operation but once it gets to operating temperature it starts misfiring and runs rough. I have checked and replaced all vacuum lines, tested and/or replaced MAP sensor, Crankshaft Position Sensor and Camshaft Position Sensor. When I changed the Camshaft Position Sensor it seemed to fix the issue but I was mistaken. After about 30 minutes of driving it started misfiring again. I am at a loss as to what to do next. Can you help me?
Many things cause misfire, so you need more information to help narrow it down (rather than showering it with parts). See our misfire topic in the FAQ.
along with P0301 and P0308 as well
So these codes indicate that you have bad misfiring on cylinders #1 and #8. It would also be useful to get misfire counts for all cylinders using a good scan tool, as well as readout of the freeze frame data for the P0300 code.
Have you inspected your spark plugs and wires, or tried swapping them around? Swapping the fuel injectors?
@imperator Thank you for the response. I was using a OBD2 scanner and those were the only codes that came up, the P0300, P0301 and P0308. I Just replaced the spark plugs less than 2 months ago. I checked spark plugs and they still look brand new, wires, coil packs and made sure there was spark, all are good. The truck runs beautiful, like it did when I first purchased it, at start up so everything works properly. It changes when the vehicle reaches operating temperature. Should I still swap the injectors around? The truck does have roughly 230K miles on it but has been taken better care of than my wife.
@imperator Thank you for your assistance. I did as you suggested and purchased a OBD2 with the Freeze Frame Data capability. I got a new code Po208 "Open circuit malfunction in number 8 fuel injector" The 8 cylinder Fuel injector quit functioning. Before I removed the fuel rail I tested all the injectors. Most of the injectors had a resistance of 14 or above but number 8, was at 2. I replaced number 8 injector and it runs beautiful again.
nice work. Thanks for reporting back.
those were the only codes that came up
misfire count isn't a DTC (diagnostic trouble code). It would be found in the live data of your scan tool, if it supports it. However, freeze frame data is usually found with DTC's. The freeze frama data provides information about the state of the engine the moment the code was triggered, and it would really help you with your troubleshooting
It changes when the vehicle reaches operating temperature
That sounds like it might be a fuel problem then. When the engine is cold, it operates on what's called "open loop" fuel metering. The fuel system blindly injects pre-programmed amounts of fuel, and ignores most sensor feedback. It guesses. Once the engine reaches operating temp, it switches to "closed-loop" mode. Now the engine starts computing all the sensor data that comes in (engine temp, air temp, exhaust O2 data, etc), and uses it to tweak the fuel mixture, adding and subtracting little by little, hundreds of times per second, to keep the engine running at peak efficiency. If any of the sensor data isn't accurate, the engine won't be able to run properly. The freeze frame data will tell you the fuel metering mode as well as the sensor values, which can give you a direction where to look for the cause of the problem.
You can also check your basic engine vitals like system voltage and fuel pressure. Again more details are in the FAQ section on this site.