Constant #6 Misfire
04-05-2017, 11:35 AM
#11
Mark
iTrader: (1)
Well, if the compression in #6 checks good then you need to trace #6 COP wires back to the ECM.
04-05-2017, 12:06 PM
#12
04-05-2017, 03:01 PM
#15
Moderator
04-05-2017, 10:50 PM
#17
05 5.4l 3v s.crew lariat
how long ago did you change boot on no 6
If it gets damaged and breaks down at 30 kv it doesn't matter if its fairly new. Move that boot and coil to another cyl one at a time . See if trouble moves .
Make sure plugs are torqued to 25-28 foot pounds and no anti seize near the tips. Did you clean carbon out of sparktip hole with carb cleaner?'
You may have to try a new injector on no 6.
Make sure plugs are torqued to 25-28 foot pounds and no anti seize near the tips. Did you clean carbon out of sparktip hole with carb cleaner?'
You may have to try a new injector on no 6.
04-05-2017, 11:12 PM
#18
If it gets damaged and breaks down at 30 kv it doesn't matter if its fairly new. Move that boot and coil to another cyl one at a time . See if trouble moves .
Make sure plugs are torqued to 25-28 foot pounds and no anti seize near the tips. Did you clean carbon out of sparktip hole with carb cleaner?'
You may have to try a new injector on no 6.
Make sure plugs are torqued to 25-28 foot pounds and no anti seize near the tips. Did you clean carbon out of sparktip hole with carb cleaner?'
You may have to try a new injector on no 6.
04-06-2017, 09:08 AM
#19
05 5.4l 3v s.crew lariat
I believe that your signal on number 6 will be off if its not firing correctly .
Being that you have done all that changing ,injectors ,boots, plugs then It is either a failing pcm output or a valve problem .
Pcm outputs can be damaged by overloads or shorts . The coil has standing 12volts on one side and the pcm pulses the ground side so a sold ground on this wire or poor insulation to grd is going to mess it up . You could also monitor the 12v side to see if you are losing it , it basically jumpers from one coil plug to the next, you could run a new jumper on number 6 without any cutting .
I would run another wire in the loom back to the pcm and temporarily cut the norm wire free both ends . That will eliminate that wire problem . There have been some reports of a short to a bracket in the area of number 5 and 6 . Rodent chewing damage on top of the engine also has been plaguing all brands of engines .
You can get your pcm repaired if you suspect number 6 output damaged , probably cheaper than a new one . You have had one indication of a pcm failure .
You may put a new plug on number six coil and injector in case there is a connection problem .
The next possibility is a valve problem ,some valve sticking has shown up on these engines from a build up behind intake valve stems .
The next valve problem could be cam rollers , my engine threw one to the side on number 8 intake . I replaced all lash adjusters and rollers when I tore it down and did timing job .
Removing the drivers side valve cover is not difficult compared to the passenger side to inspect for worn rollers or worse .
From what you say I would lean to pcm signal failure .
Pcm outputs can be damaged by overloads or shorts . The coil has standing 12volts on one side and the pcm pulses the ground side so a sold ground on this wire or poor insulation to grd is going to mess it up . You could also monitor the 12v side to see if you are losing it , it basically jumpers from one coil plug to the next, you could run a new jumper on number 6 without any cutting .
I would run another wire in the loom back to the pcm and temporarily cut the norm wire free both ends . That will eliminate that wire problem . There have been some reports of a short to a bracket in the area of number 5 and 6 . Rodent chewing damage on top of the engine also has been plaguing all brands of engines .
You can get your pcm repaired if you suspect number 6 output damaged , probably cheaper than a new one . You have had one indication of a pcm failure .
You may put a new plug on number six coil and injector in case there is a connection problem .
The next possibility is a valve problem ,some valve sticking has shown up on these engines from a build up behind intake valve stems .
The next valve problem could be cam rollers , my engine threw one to the side on number 8 intake . I replaced all lash adjusters and rollers when I tore it down and did timing job .
Removing the drivers side valve cover is not difficult compared to the passenger side to inspect for worn rollers or worse .
From what you say I would lean to pcm signal failure .
04-06-2017, 10:50 AM
#20
Being that you have done all that changing ,injectors ,boots, plugs then It is either a failing pcm output or a valve problem .
Pcm outputs can be damaged by overloads or shorts . The coil has standing 12volts on one side and the pcm pulses the ground side so a sold ground on this wire or poor insulation to grd is going to mess it up . You could also monitor the 12v side to see if you are losing it , it basically jumpers from one coil plug to the next, you could run a new jumper on number 6 without any cutting .
I would run another wire in the loom back to the pcm and temporarily cut the norm wire free both ends . That will eliminate that wire problem . There have been some reports of a short to a bracket in the area of number 5 and 6 . Rodent chewing damage on top of the engine also has been plaguing all brands of engines .
You can get your pcm repaired if you suspect number 6 output damaged , probably cheaper than a new one . You have had one indication of a pcm failure .
You may put a new plug on number six coil and injector in case there is a connection problem .
The next possibility is a valve problem ,some valve sticking has shown up on these engines from a build up behind intake valve stems .
The next valve problem could be cam rollers , my engine threw one to the side on number 8 intake . I replaced all lash adjusters and rollers when I tore it down and did timing job .
Removing the drivers side valve cover is not difficult compared to the passenger side to inspect for worn rollers or worse .
From what you say I would lean to pcm signal failure .
Pcm outputs can be damaged by overloads or shorts . The coil has standing 12volts on one side and the pcm pulses the ground side so a sold ground on this wire or poor insulation to grd is going to mess it up . You could also monitor the 12v side to see if you are losing it , it basically jumpers from one coil plug to the next, you could run a new jumper on number 6 without any cutting .
I would run another wire in the loom back to the pcm and temporarily cut the norm wire free both ends . That will eliminate that wire problem . There have been some reports of a short to a bracket in the area of number 5 and 6 . Rodent chewing damage on top of the engine also has been plaguing all brands of engines .
You can get your pcm repaired if you suspect number 6 output damaged , probably cheaper than a new one . You have had one indication of a pcm failure .
You may put a new plug on number six coil and injector in case there is a connection problem .
The next possibility is a valve problem ,some valve sticking has shown up on these engines from a build up behind intake valve stems .
The next valve problem could be cam rollers , my engine threw one to the side on number 8 intake . I replaced all lash adjusters and rollers when I tore it down and did timing job .
Removing the drivers side valve cover is not difficult compared to the passenger side to inspect for worn rollers or worse .
From what you say I would lean to pcm signal failure .
I found a company online that sells reman pcm's with programmed keys and lifetime warranty for about $350.....so I might be ordering one up in the next few days.