P0301 On 2003 Ford F150 4.6L
09-12-2016, 06:29 PM
#1
Junior Member
Thread Starter
P0301 On 2003 Ford F150 4.6L
I am at about my wits end with this P0301 (Misfire On Cylinder #1) code. I've replaced the coil pack on that cylinder, all the spark plugs, and replaced the fuel injector on that cylinder. We keep clearing the code and it keeps on coming back.
The weird thing is that it only misfires after the truck has set for a few hours and then it only misfires when I first put it in gear. Once I am out of the driveway and on the road it's fine for most of the day unless I let it sit for several hours and then it might misfire again.
We noticed that the connector to the fuel injector is wobbly and doesn't snap tight to the fuel injector (before and after it was replaced) due to the clips on the side not working well. We zip tied it together this afternoon to make it fit tightly to the fuel injector to see if that works.
Any ideas as to what could be causing this? Other than that misfire the engine sounds great and the trucks runs very well.
The weird thing is that it only misfires after the truck has set for a few hours and then it only misfires when I first put it in gear. Once I am out of the driveway and on the road it's fine for most of the day unless I let it sit for several hours and then it might misfire again.
We noticed that the connector to the fuel injector is wobbly and doesn't snap tight to the fuel injector (before and after it was replaced) due to the clips on the side not working well. We zip tied it together this afternoon to make it fit tightly to the fuel injector to see if that works.
Any ideas as to what could be causing this? Other than that misfire the engine sounds great and the trucks runs very well.
09-18-2016, 03:55 PM
#2
LightningRod
Mike
Freeze frame data might be helpful. If your code reader is capable of monitoring live data, that might provide new clues to help sort things out.
You have covered pretty much all the hard causes for a specific cyl misfire - except perhaps electrical flaky electrical connections that cop or injector at the PCM plug end. But my opinion, that is probably doubtful.
But I think you may be seeing the beginning of an unrelated problem. OBD II codes are like the old saying, "The weakest link breaks first". Perhaps a temp sensor (IAT) or (EOT), Trans Oil Temp, Ambient Air temp, barometric pressure or fuel rail pressure sensor (which is relative to manifold pressure) is giving the ECU a bumb reading. Then, based on that bumb reading it is trying to compensate and adjusts some parameter just near borderline conditions (say lean or perhaps rich fuel air/ratio) and Cyl 1 'barffs' first. Freeze frame data will give you a birds eye view into all kinds of other stuff going on at the time of the misfire.
JMO. Don't get bogged down in the thinking that a code is component specific.
Freeze frame data might be helpful. If your code reader is capable of monitoring live data, that might provide new clues to help sort things out.
You have covered pretty much all the hard causes for a specific cyl misfire - except perhaps electrical flaky electrical connections that cop or injector at the PCM plug end. But my opinion, that is probably doubtful.
But I think you may be seeing the beginning of an unrelated problem. OBD II codes are like the old saying, "The weakest link breaks first". Perhaps a temp sensor (IAT) or (EOT), Trans Oil Temp, Ambient Air temp, barometric pressure or fuel rail pressure sensor (which is relative to manifold pressure) is giving the ECU a bumb reading. Then, based on that bumb reading it is trying to compensate and adjusts some parameter just near borderline conditions (say lean or perhaps rich fuel air/ratio) and Cyl 1 'barffs' first. Freeze frame data will give you a birds eye view into all kinds of other stuff going on at the time of the misfire.
JMO. Don't get bogged down in the thinking that a code is component specific.
