Misfire
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Joined: Jul 2019
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From: acworth, NH
Misfire
I have a 2011 ranger 2.3. Misfires with code of random. Cyl 3 has most. Head has been redone timing was double checked injectors have good pattern compression is good. I found my ltft to be at 8 with just key on..also a fault in Kam power. not sure if this fault is causing my misfire or unrelated and why is my ltft at 8 I expect 0. Please any ideas
Welcome to the forum
LTFT(long term fuel trim) can NOT be set to 0 by OBD2 reader, computer uses LTFT for cold start(no O2 sensors) and to offset it's air/fuel calculations as engine system ages, i.e. small air leaks and lower fuel pressure.
+8 LTFT is OK, and its not a "running" number, it will change over time if STFT averages change and if rear O2 changes
KAM, keep alive memory, should be addressed, there is a fuse for that in engine bay fuse box, LTFT is held regardless of backup power, KAM, so won't go to 0 ever, Ford Dealer Scanners can make it 0 I believe, and maybe Forscan
But LTFT isn't the source of the misfires.
CAM sensor can effect misfires, and I assume these are REAL misfires, you can feel them when driving?
LTFT(long term fuel trim) can NOT be set to 0 by OBD2 reader, computer uses LTFT for cold start(no O2 sensors) and to offset it's air/fuel calculations as engine system ages, i.e. small air leaks and lower fuel pressure.
+8 LTFT is OK, and its not a "running" number, it will change over time if STFT averages change and if rear O2 changes
KAM, keep alive memory, should be addressed, there is a fuse for that in engine bay fuse box, LTFT is held regardless of backup power, KAM, so won't go to 0 ever, Ford Dealer Scanners can make it 0 I believe, and maybe Forscan
But LTFT isn't the source of the misfires.
CAM sensor can effect misfires, and I assume these are REAL misfires, you can feel them when driving?
Member
Joined: Dec 2018
Posts: 373
Likes: 23
From: Roswell New mex
Check and make sure your crank position sensor is good as mine actually shatterdled on the freeway last night and started to misfire, I had to run limp mode home and buy a new sensor, it is what controls your spark timing advance on these duratec motors, I tested with a timing light too, all the way up will retard, all the way down will advance, all the way down and the motor at 5k will be at 40 degrees advance and and all the way up will be at 34 degrees, your idle should sit between -2 and 5 degrees anything outside of that is no no
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