Plug wires

FED 387 · 09-28-2018, 10:58 AM

Are the **new** plug wires following the same routing path that the **old** wires did---

have you installed or rerouted any sensitive wiring since the old wires were replaced???

are all wires the same length as the wires they replaced???

are the boots OK do they have carbon tracking inside them???

MSD suggests that 40-50 OHMS per wire foot COLD is their recommended number----

is it the same cylinder or does it move around???

have you thoroughly checked the distributor/cap rotor/wiring and coil ---how old is the coil do you have a **powerful** enough coil for the application

do you have a MSD box and has it been checked out-- did you try a different box

was the coil and or coil wire replaced??

have you checked for a cracked porcelain or other possible defect of each spark plug??

what else was changed??? If you have the **old stuff** put it back in see if the miss goes away

does it happen on humid days or dry days-- cool days or hot days or does it happen almost any time??? low RPM or High RPM ??

FED 387

nhramnl · 09-28-2018, 12:16 PM

[QUOTE=FED 387;573841]
If you have the **old stuff** put it back in see if the miss goes away

Best advice there is, right there. It ran fine, you changed some things, now it misses. Put all of the "old stuff" back on and if you lose the miss, starting replacing old pieces with new, one piece at a time. Obviously, the piece that brings back the miss is the culprit.

cad · 09-28-2018, 01:23 PM

Id replace the coil wire at a minimum, and possibly the coil.
Also, did you run the MSD ignition box positive and negative straight to battery?

Both of these issues (engine misses) happened this season on 2 different cars. Fixes were immediate when corrected.

We have a MSD tester and the ignition boxes tested fine on both cars during the issue.

09-28-2018, 10:58 AM	#1
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,421 Likes: 529 Liked 333 Times in 180 Posts	Re: Plug wires Are the new plug wires following the same routing path that the old wires did--- have you installed or rerouted any sensitive wiring since the old wires were replaced??? are all wires the same length as the wires they replaced??? are the boots OK do they have carbon tracking inside them??? MSD suggests that 40-50 OHMS per wire foot COLD is their recommended number---- is it the same cylinder or does it move around??? have you thoroughly checked the distributor/cap rotor/wiring and coil ---how old is the coil do you have a powerful enough coil for the application do you have a MSD box and has it been checked out-- did you try a different box was the coil and or coil wire replaced?? have you checked for a cracked porcelain or other possible defect of each spark plug?? what else was changed??? If you have the old stuff put it back in see if the miss goes away does it happen on humid days or dry days-- cool days or hot days or does it happen almost any time??? low RPM or High RPM ?? FED 387 Last edited by FED 387; 09-28-2018 at 11:01 AM. Reason: spelling

09-28-2018, 12:16 PM	#2
nhramnl Senior Member Join Date: Feb 2010 Posts: 507 Likes: 8 Liked 358 Times in 83 Posts	Re: Plug wires [QUOTE=FED 387;573841] If you have the old stuff put it back in see if the miss goes away Best advice there is, right there. It ran fine, you changed some things, now it misses. Put all of the "old stuff" back on and if you lose the miss, starting replacing old pieces with new, one piece at a time. Obviously, the piece that brings back the miss is the culprit.

09-28-2018, 01:23 PM	#3
cad Senior Member Join Date: Apr 2009 Location: Omaha, NE Posts: 702 Likes: 202 Liked 91 Times in 51 Posts	Re: Plug wires Id replace the coil wire at a minimum, and possibly the coil. Also, did you run the MSD ignition box positive and negative straight to battery? Both of these issues (engine misses) happened this season on 2 different cars. Fixes were immediate when corrected. We have a MSD tester and the ignition boxes tested fine on both cars during the issue.