3.4l DOHC misfire - DTC p1640
04-13-2013, 07:53 PM
#11
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Disconnecting the battery and touching the cables together is not just to reset the codes, it may reset the computer and correct the problem.
Most misfires are due to a bad plug or plug wire. If you are convinced the plugs and wires are good I would try switching the #6 injector with one of the other positions and see if the misfire follows the injector. Also, try switching coils around and see if the misfire follows the coil from #6. If it is not a bad plug, bad plug wire, bad injector or bad coil, I would do a compression test to see if #6 is low, which would indicate an internal engine mechanical issue.
Even if the plug wires are new, you might want to check the resistance on the #6 wire. It wouldn't be the first time an issue is related to a new part.
Most misfires are due to a bad plug or plug wire. If you are convinced the plugs and wires are good I would try switching the #6 injector with one of the other positions and see if the misfire follows the injector. Also, try switching coils around and see if the misfire follows the coil from #6. If it is not a bad plug, bad plug wire, bad injector or bad coil, I would do a compression test to see if #6 is low, which would indicate an internal engine mechanical issue.
Even if the plug wires are new, you might want to check the resistance on the #6 wire. It wouldn't be the first time an issue is related to a new part.
The other suggestions ill have to try but the injectors and coils are in the most ingorant spots. So it'll be an all day adventure to ge to them.
I also need to get a compression test done. Who knows I might have a few burnt exhaust valves?
04-13-2013, 08:10 PM
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04-13-2013, 08:26 PM
#13
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Not necessarily the ICM, but a bad coil would show up on both cylinders. If the PCM is detecting a misfire on a particular cylinder, start with the spark plug wire/sparkplug. Swap them BOTH to another cylinder(like #4) and see if the error code follows the parts. If the misfire is still on #6, move the injector to #4 and check for the code again.
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04-20-2013, 02:14 AM
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I swapped #6'* plug and plug wire with #4'* plug and plug wire. Misfire stayed at #6. Doing a compression test either today or sunday, and if its not this, Im doing coils and and ICM next. Will follow up with my results..
04-20-2013, 05:13 AM
#16
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Swap the coil also.
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04-20-2013, 10:29 AM
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Not so sure about switching the coils, but it is easy to do and will rule out one possibility. I would definitely try switching injectors though. I still think that is a very likely candidate for what is causing your misfire.
04-20-2013, 11:40 PM
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Got a coil and put it in. Miss is still there, but it seems more smooth then before (I think). I'm hoping to run a compression check tomorrow. If it'* not that then I'm onto replacing the icm.
04-21-2013, 09:27 PM
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Ran a compression check on cylinders 2,4,6. #2 was 125psi, #4 was 145psi , and #6 was 145 psi. So they were in spec. Newly replaced coil, and its still misfiring. Later on in the week when Iget time I will try swapping the fuel injectors and or replace it.
04-22-2013, 07:41 AM
#20
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Is it missing when sitting in the driveway and idling, or just at WOT? If it is missing at idle you can use a wooden dowel to listen to each injector. You should hear a rhythmic mechanical click from each one. If it is missing, and you do get the clicking sound on the #6 injector, the injector is firing but could be plugged. If you don't get the clicking sound, disconnect the electrical connection from the injector and probe the two terminals on the wire side of the connector with a volt meter, start the car and see if you get 12 volts. If you get 12 volts but the injector is not clicking, replace the injector.
If it is not missing at idle, the best way to check is by switching injectors around to see if the misfire follows the suspect injector.
If it is not missing at idle, the best way to check is by switching injectors around to see if the misfire follows the suspect injector.