Misfire code after replacing coil packs?
08-17-2018, 05:19 PM
#1
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Misfire code after replacing coil packs?
2001 4.2 was bucking on acceleration at low speeds. No codes showing so just replaced coil packs because car is at 96k. Car is running better but now I'm getting misfire codes in all 8 cylinders. Now sure what to make of this?
08-17-2018, 06:38 PM
#3
Crappy coils? The coils on the 4.2 rarely fail. I'd put some new plugs in, swap the old coils back, clear codes, drive and check codes...in both engine and trans.
08-17-2018, 07:04 PM
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Your probably right, got packs off Amazon for $100. I wasn't getting any misfire codes or any codes at all prior to putting in the crappy new coils so I think I'll take your advise and switch back and see what happens. I did put new NGK BKR6EKUB plugs so I'll keep those in.
I regret cheeping out on the coils but it seems odd to me that immediately after putting them in I got misfires on all 8 even though it seems to run better and the low RPM bucking is reduced. Is there a possibility that the ECU is adjusting to the new coils and plugs and that the misfire CELs might go away on their own, or am I grasping a straws?
I regret cheeping out on the coils but it seems odd to me that immediately after putting them in I got misfires on all 8 even though it seems to run better and the low RPM bucking is reduced. Is there a possibility that the ECU is adjusting to the new coils and plugs and that the misfire CELs might go away on their own, or am I grasping a straws?
08-17-2018, 07:12 PM
#5
Your probably right, got packs off Amazon for $100. I wasn't getting any misfire codes or any codes at all prior to putting in the crappy new coils so I think I'll take your advise and switch back and see what happens. I did put new NGK BKR6EKUB plugs so I'll keep those in.
I regret cheeping out on the coils but it seems odd to me that immediately after putting them in I got misfires on all 8 even though it seems to run better and the low RPM bucking is reduced. Is there a possibility that the ECU is adjusting to the new coils and plugs and that the misfire CELs might go away on their own, or am I grasping a straws?
I regret cheeping out on the coils but it seems odd to me that immediately after putting them in I got misfires on all 8 even though it seems to run better and the low RPM bucking is reduced. Is there a possibility that the ECU is adjusting to the new coils and plugs and that the misfire CELs might go away on their own, or am I grasping a straws?
The 4.2 uses good (read: expensive) coils.
08-17-2018, 07:36 PM
#6
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Car only has 96k on it so you're probably right, it's not the coils and that's why I wasn't getting any codes. I'll try swapping in the original coils and keeping the new plugs. I'm just hoping the low RPM bucking is not a transmission issue. Hopefully it's not because changing the coils/plugs made it about 75% better. I'll post back.
I did notice OEM 4.2 coils are expensive, that's why I cheeped out on the new ones. Any idea how long original 4.2 coils can last?
I did notice OEM 4.2 coils are expensive, that's why I cheeped out on the new ones. Any idea how long original 4.2 coils can last?
08-17-2018, 09:08 PM
#7
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I just realized the original plugs are platinum (4 prong) and I replaced them with standard (single prong). I wonder if that be the reason for the misfire codes on all 8 cylinders?
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08-18-2018, 07:17 AM
#8
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I would go with the 4 prong plugs. A couple of years ago I changed mine just because I wasn't sure about previous maintenance and the plugs looked like they had been in a long time. No misfires or anything just paranoia. According to the trip computer on the car my mpg increased immediately. First tank of fuel after the change it went up by approx. 2 mpg. Bear in mind there is a big difference with these cars between saving a few bucks on parts versus buying cheap parts. Your best bet is shopping sales at the major aftermarket vendors. Sometimes you can find what you are looking for on Ebay, but be careful. I doubt the misfires are due to the plugs although that is a possibility. My money says it's the cheap coils. Chinese knock-offs, maybe?
08-18-2018, 01:10 PM
#9
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Defiantly was the cheap coils. I just swapped back in the original coils and left in the new plugs and all codes went away with the exception of 1 misfire code in cylinder #7. I swapped out the coils and the plugs but the code still persists in #7 only. The engine light is not coming on anymore but when I pull the codes, #7 misfire is still there. I'm stumped? Perhaps I'll just drive it a bit and see if the ECU adjusts.
The new plugs I have in there now are 2 prong copper, not 1. I read somewhere that the 2 prong copper NGK where a good choice for the 4.2 but I'll probably take your advise and go back to 4 prong platinum NGK plugs that where originally in there a soon as I can figure the remaining #7 misfire issue.
The new plugs I have in there now are 2 prong copper, not 1. I read somewhere that the 2 prong copper NGK where a good choice for the 4.2 but I'll probably take your advise and go back to 4 prong platinum NGK plugs that where originally in there a soon as I can figure the remaining #7 misfire issue.
