Glenn Humbert
New Member
Greetings. I am trying to chase down a persistent P0354 and I have a few questions for anyone who would like to chime in.
Basics:
03 Liberty with > 170K. Changed the clutch last year and due to a stubborn pilot bearing I pulled the whole motor, and did some basic cleanup of the wiring etc. Was running great. New vlave cover gaskets, so the valve train got a basic visual inspection with no obvious looking issues (I know this is far from perfect, but just indicating things looked good and I didn't feel compelled to do more).
On the road about a week ago the CEL comes on - then starts flashing - and it stumbles badly - letting off the throttle recovers and taking it very easy gets me home. There was however, and unnoticed crack in the coolant overflow air bleed line that was dripping some coolant in the area of Cylinder 4.
Cleaned up coolant, replaced line, used original parts after cleaning them up as well (including the spark plug hole and FI connector) - still throwing same codes
Replaced Coil - no change - except the CEL does not come on immediately. Replaced Spark plug, same.
Swapped with another cylinder - persists at cylinder 4.
Cleaned engine to chassis grounds, same.
Checked all wiring for continuity to PCM and PDC (Coils and Injectors), all good. Swapped with yet another cylinder, still throwing codes on 4.
I have not done a leak down test because I have to get the proper equipment (money is a bit tight)
Another curious thing - with the scan tool connected while driving, when the issue becomes severe enough for the stumble to occur, the scan tool loses connection.
Also, the last check I notice the STFT B1 at 99% - in this instance it did not throw the misfire.
I am concerned the P0304 (misfire) is the result of the response to the initial code for the ignition circuit, and that the whole issue could be the PCM.
Just throwing this up there to see what others think, its going to be a couple of days until I can leak down test it anyway. It was running great before this.
Basics:
03 Liberty with > 170K. Changed the clutch last year and due to a stubborn pilot bearing I pulled the whole motor, and did some basic cleanup of the wiring etc. Was running great. New vlave cover gaskets, so the valve train got a basic visual inspection with no obvious looking issues (I know this is far from perfect, but just indicating things looked good and I didn't feel compelled to do more).
On the road about a week ago the CEL comes on - then starts flashing - and it stumbles badly - letting off the throttle recovers and taking it very easy gets me home. There was however, and unnoticed crack in the coolant overflow air bleed line that was dripping some coolant in the area of Cylinder 4.
Cleaned up coolant, replaced line, used original parts after cleaning them up as well (including the spark plug hole and FI connector) - still throwing same codes
Replaced Coil - no change - except the CEL does not come on immediately. Replaced Spark plug, same.
Swapped with another cylinder - persists at cylinder 4.
Cleaned engine to chassis grounds, same.
Checked all wiring for continuity to PCM and PDC (Coils and Injectors), all good. Swapped with yet another cylinder, still throwing codes on 4.
I have not done a leak down test because I have to get the proper equipment (money is a bit tight)
Another curious thing - with the scan tool connected while driving, when the issue becomes severe enough for the stumble to occur, the scan tool loses connection.
Also, the last check I notice the STFT B1 at 99% - in this instance it did not throw the misfire.
I am concerned the P0304 (misfire) is the result of the response to the initial code for the ignition circuit, and that the whole issue could be the PCM.
Just throwing this up there to see what others think, its going to be a couple of days until I can leak down test it anyway. It was running great before this.
