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I have a 2004 PT Cruiser with 261,500 miles. The engine and transmission are essentially original, with the exception of normal maintenance and an oil pressure switch and a belt tensioner.
I occasionally experience a misfire at idle, almost always when I come to a stop after running the engine at high RPM, such as having the car downshift while passing). The engine will misfire when stopped at a light, smooth out and run fine while driving, and then misfire again when I stop. Usually after shutting off the car and having it sit for a bit, everything runs fine when I start it up, and it idles smoothly. I normally get a P0302, P0303, or P0304 code if the CEL lights. If the CEL starts to flash, it goes out when I start moving again.
Last night, if was misfiring badly (after some higher speed driving). I checked the codes, and I had a P0300, with two codes pending (P0300 and P0304). The freeze frame data is:
Throttle Position: 14.5%, Engine RPM: 325, Load Value: 60.3%, MAP Sensor: 68 KPA, Coolant Temp: 176 degrees F, Intake Air Temp: 134 degrees F, Ignition Timing Advance: 10.0 degrees, Short Term Fuel Trim1: 0.0%, Long Term Fuel Trim1: -2.2%, Short Term Fuel Trim3: 50.0%, Long Term Fuel Trim3: 38.2%, Vehicle Speed: 0 MPH, Fuel System1: OPEN
I have changed the plugs and wires a couple of thousand miles ago. The car runs fine and accelerates fine. I'm leaning towards the fuel injectors since the are original, and I noticed that if I move them a bit, the problem seems to disappear for a while. In addition, the fact that the misfire location seems to occur in different cylinders at random times .makes me think that as well. I'm wondering if high speed operation causes the old injectors to have issues during normal operation.
Any thoughts, ideas, or anything indicated by the freeze frame data would be greatly appreciated.
Thanks,
Doug
I occasionally experience a misfire at idle, almost always when I come to a stop after running the engine at high RPM, such as having the car downshift while passing). The engine will misfire when stopped at a light, smooth out and run fine while driving, and then misfire again when I stop. Usually after shutting off the car and having it sit for a bit, everything runs fine when I start it up, and it idles smoothly. I normally get a P0302, P0303, or P0304 code if the CEL lights. If the CEL starts to flash, it goes out when I start moving again.
Last night, if was misfiring badly (after some higher speed driving). I checked the codes, and I had a P0300, with two codes pending (P0300 and P0304). The freeze frame data is:
Throttle Position: 14.5%, Engine RPM: 325, Load Value: 60.3%, MAP Sensor: 68 KPA, Coolant Temp: 176 degrees F, Intake Air Temp: 134 degrees F, Ignition Timing Advance: 10.0 degrees, Short Term Fuel Trim1: 0.0%, Long Term Fuel Trim1: -2.2%, Short Term Fuel Trim3: 50.0%, Long Term Fuel Trim3: 38.2%, Vehicle Speed: 0 MPH, Fuel System1: OPEN
I have changed the plugs and wires a couple of thousand miles ago. The car runs fine and accelerates fine. I'm leaning towards the fuel injectors since the are original, and I noticed that if I move them a bit, the problem seems to disappear for a while. In addition, the fact that the misfire location seems to occur in different cylinders at random times .makes me think that as well. I'm wondering if high speed operation causes the old injectors to have issues during normal operation.
Any thoughts, ideas, or anything indicated by the freeze frame data would be greatly appreciated.
Thanks,
Doug