Hello All.
I don't have much fight left before going to the dealer. I am experiencing the dreaded P300 misfire code. Before finding so much information on the misfire being a common thing for this vehicle (5th Gen Ram 1500), I approached it as a typical misfire and replaced the spark plugs and coil packs. Immediately afterwards, the truck ran great but only for about 2 days. CEL(Check Engine Light) came back and turns off from time to time but never for good. I'm not sure my issue is a computer issue though because I can actually feel a "miss" when idling. Drives well at RPM's over idle speed. My idle RPM's seem low(very close to 500) and seems to trigger the CEL when I let it idle for too long.
Summary:
Nov - First time CEL came on while going into overdrive on the freeway (blinking check engine light). It stopped blinking after my RPM's lowered back to a normal level. Check engine light went away by itself later that day.
Dec - CEL resurfaced and would start blinking if I let it idle for too long (about 10min). Living in cold climate, this would happen when trying to warm the truck before getting in to drive. When the CEL would blink, the truck started to experience stutters when accelerating at any speed.
Jan - I performed spark plug and coil pack replacement on all 6 cylinders. I wiped out the interior of the upper intake in the process because I noticed the residue on the walls. Truck ran like new for about 2 days but CEL soon returned. I noticed the idle speed seemed low at this time. I reset the computer a couple of times by disconnecting the battery. Code would leave but come back. After that, I purchased a new code reader (Harbor Freight MR16) that has more bells and whistles than the 15 year old reader I'd been using to allow me to have more access to the vehicle systems. I just kept getting the misfire codes. Now, I can see some live data which is useful if you have a good understanding of things but this is my first time trying to diagnose a random misfire and I'm learning as I go.
Feb - I did a relearn of the Throttle Position but that didn't do anything for my low idle. I did an intake clean with the Seafoam spray can and straw setup. That process seemed to introduce new codes into the system because of the straw insertion procedure that leaves some room for a vac leak. I reset the computer again and that got rid of all the additional "U" codes I got from doing the intake cleaning. The P300 code remained. I started to dive deeper into the code reader and can see cylinder misfires in 2,4, & 6 cylinders. Cylinders 1,3, & 5 have zero misfires. Does this mean there could be an issue with the O2 sensor?
For what it's worth, I've also been running Seafoam in the gas tank to try and help clean out the system. After reading others' misfire troubles, I'm not sure if this can be a software issue or if it's a legitimate problem. The misfire seems real at idle when parked or stopped. I can't detect any abnormal behavior at any higher RPM's except in the instances stated above.
Any input/help is greatly appreciated!
I don't have much fight left before going to the dealer. I am experiencing the dreaded P300 misfire code. Before finding so much information on the misfire being a common thing for this vehicle (5th Gen Ram 1500), I approached it as a typical misfire and replaced the spark plugs and coil packs. Immediately afterwards, the truck ran great but only for about 2 days. CEL(Check Engine Light) came back and turns off from time to time but never for good. I'm not sure my issue is a computer issue though because I can actually feel a "miss" when idling. Drives well at RPM's over idle speed. My idle RPM's seem low(very close to 500) and seems to trigger the CEL when I let it idle for too long.
Summary:
Nov - First time CEL came on while going into overdrive on the freeway (blinking check engine light). It stopped blinking after my RPM's lowered back to a normal level. Check engine light went away by itself later that day.
Dec - CEL resurfaced and would start blinking if I let it idle for too long (about 10min). Living in cold climate, this would happen when trying to warm the truck before getting in to drive. When the CEL would blink, the truck started to experience stutters when accelerating at any speed.
Jan - I performed spark plug and coil pack replacement on all 6 cylinders. I wiped out the interior of the upper intake in the process because I noticed the residue on the walls. Truck ran like new for about 2 days but CEL soon returned. I noticed the idle speed seemed low at this time. I reset the computer a couple of times by disconnecting the battery. Code would leave but come back. After that, I purchased a new code reader (Harbor Freight MR16) that has more bells and whistles than the 15 year old reader I'd been using to allow me to have more access to the vehicle systems. I just kept getting the misfire codes. Now, I can see some live data which is useful if you have a good understanding of things but this is my first time trying to diagnose a random misfire and I'm learning as I go.
Feb - I did a relearn of the Throttle Position but that didn't do anything for my low idle. I did an intake clean with the Seafoam spray can and straw setup. That process seemed to introduce new codes into the system because of the straw insertion procedure that leaves some room for a vac leak. I reset the computer again and that got rid of all the additional "U" codes I got from doing the intake cleaning. The P300 code remained. I started to dive deeper into the code reader and can see cylinder misfires in 2,4, & 6 cylinders. Cylinders 1,3, & 5 have zero misfires. Does this mean there could be an issue with the O2 sensor?
For what it's worth, I've also been running Seafoam in the gas tank to try and help clean out the system. After reading others' misfire troubles, I'm not sure if this can be a software issue or if it's a legitimate problem. The misfire seems real at idle when parked or stopped. I can't detect any abnormal behavior at any higher RPM's except in the instances stated above.
Any input/help is greatly appreciated!
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