Misfire at idle, not so much under load.
04-07-2013, 09:00 PM
#1
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Misfire at idle, not so much under load. I have a misfire at idle that seems to go away when the throttle is applied.
With a professional scanner hooked up I see about 1-6 counts on 1-2 cylinders at a time. Open loop sees less misses than closed loop.
I have switched coils around, it doesn't seem to be coils.
My plug wires are new though I will probably ohm them out this week.
My plugs are new- AC Delco Iridium.
I tried putting a few different plugs in and the misfire was still in those cylinders.
My o2's are new and functioning properly.
My injectors as far as I know are functioning properly, though my new plugs that I pulled out seemed very very clean...
It is a small misfire that is hard to notice, but it still seems to be there..
Could it possibly be a Crank Position Sensor, Cam Position Sensor, or PCM going bad? The PCM doesn't set off a light for this miss.
With a professional scanner hooked up I see about 1-6 counts on 1-2 cylinders at a time. Open loop sees less misses than closed loop.
I have switched coils around, it doesn't seem to be coils.
My plug wires are new though I will probably ohm them out this week.
My plugs are new- AC Delco Iridium.
I tried putting a few different plugs in and the misfire was still in those cylinders.
My o2's are new and functioning properly.
My injectors as far as I know are functioning properly, though my new plugs that I pulled out seemed very very clean...
It is a small misfire that is hard to notice, but it still seems to be there..
Could it possibly be a Crank Position Sensor, Cam Position Sensor, or PCM going bad? The PCM doesn't set off a light for this miss.
Last edited by SteveWs6; 04-07-2013 at 09:10 PM.
04-09-2013, 09:32 AM
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Launching!
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Please explain to me what readings to get and i'll gladly get them. Does this mean air to fuel ratio? I have gone into that category of the scanner but I can never seem to find any substantial information. Thanks for the feedback btw
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04-09-2013, 11:00 AM
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My belief is that his is from how the PCM swings the
fueling to get its "cross counts" (proportional fueling).
If the sensors get slow or the tube before them gets
longer, the prop fueling overtravels more into the
mixture weeds and at the endpoints you will get to
misfiring.
But mine did it a little, even stock. Same thing applies,
the fueling is forced away from stoich and a hiccup
is the likely outcome.
Means nothing, as described. Just a behavior.
fueling to get its "cross counts" (proportional fueling).
If the sensors get slow or the tube before them gets
longer, the prop fueling overtravels more into the
mixture weeds and at the endpoints you will get to
misfiring.
But mine did it a little, even stock. Same thing applies,
the fueling is forced away from stoich and a hiccup
is the likely outcome.
Means nothing, as described. Just a behavior.
04-09-2013, 12:29 PM
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My belief is that his is from how the PCM swings the
fueling to get its "cross counts" (proportional fueling).
If the sensors get slow or the tube before them gets
longer, the prop fueling overtravels more into the
mixture weeds and at the endpoints you will get to
misfiring.
But mine did it a little, even stock. Same thing applies,
the fueling is forced away from stoich and a hiccup
is the likely outcome.
Means nothing, as described. Just a behavior.
fueling to get its "cross counts" (proportional fueling).
If the sensors get slow or the tube before them gets
longer, the prop fueling overtravels more into the
mixture weeds and at the endpoints you will get to
misfiring.
But mine did it a little, even stock. Same thing applies,
the fueling is forced away from stoich and a hiccup
is the likely outcome.
Means nothing, as described. Just a behavior.
It is a very minor stumble but I just wanted to be sure that everything is okay. I could barely notice it but once I saw on the scanner that it is missing a little bit, it's just been eating away at my mind..
Thanks Jimmy please let me know if you have any other thoughts!
