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Old 06-25-2013, 11:10 AM
catamount catamount is offline
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Join Date: Feb 2012
Boat: 1987 ProStar 190
Location: Vermont
Posts: 502
Exclamation FYI: Spark plug wire routing... don't be too neat!

Last year as part of a general tuneup I put new wires on my 351W.

I thought that I was doing a neat job when I used zip-ties to separate and route the wires neatly parallel to each other.

However, I was then experiencing some random missing and noticing some funky off-timed flashes with my timing light. This was particularly noticeable when the engine got warmed up.

After some googling, I found this Ford TSB. Wires of sequential cylinders routed next to each other can trigger induction firing and touch off cylinders at as much as 90 degrees advanced. I am certain I was experiencing symptoms of this, even with my brand new Mallory 8mm wires.

On the 5.8 351W, cylinders 1 & 3 and 5 & 6 can be problematic. Please note that in the diagram below, they have #1 wire crossing at 90 degrees to #3 and #5 crossing below #6.

Since correcting my wires, my engine seems to run much better.

ISSUE: Engine miss, spark knock, buck/jerk, surge and other driveability concerns may be caused by induction crossfire. This occurs because of improperly routed spark plug wires.

ACTION: If spark plug replacement is performed, the correct firing order and spark plug wire routing is essential to prevent the possibility of induction crossfire between cylinders. Refer to the following procedures for inspection of the spark plug wire routing and firing order. Properly reroute the spark plug wires if required.

Whenever a high-tension ignition wire is removed from a spark plug, the distributor cap, or the coil to perform a maintenance operation, Silicone Dielectric Compound must be applied to the boot before reconnection. Using a small clean screwdriver, apply a thin layer of Silicone Dielectric Compound on the entire interior surface of the boot. Do not apply compound to metal terminals.


The firing order for 5.0Ls & all 5.8Ls is 1-3-7-2-6-5-4-8. On these vehicles the #1 and #3, or #5 and #6 spark plug wires must be separated to eliminate the possibility of an induction crossfire.
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Old 06-25-2013, 03:55 PM
CantRepeat's Avatar
CantRepeat CantRepeat is online now
Join Date: Jul 2008
Boat: Passively looking for a CSX 265
Location: Roll Tide!!
Posts: 14,571
Great find, fix and post!!!


"Heavy" beer is for wine drinkers that are too embarrassed to drink wine in front of their buddies. "Light" beer is a drinkin' man's beer!
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Old 06-25-2013, 07:27 PM
john jones john jones is offline
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Join Date: Feb 2011
Boat: 2002 Xstar
Location: Oregon
Posts: 345
I will be working on this tonight! Thanks for the info.
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Old 06-25-2013, 09:20 PM
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pbgbottle pbgbottle is offline
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Join Date: Oct 2011
Boat: 1988 tristar 190
Location: Cloverdale B.C. Canada
Posts: 414
nice will have to check mine out

1988 mastercraft tristar (open bow).
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Old 06-25-2013, 10:41 PM
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d2jp d2jp is online now
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Join Date: Jun 2011
Boat: 1992 PS 205-351w,285HO
Location: Smith Mountain Lake, VA
Posts: 899
Awesome find, and I copied your install last year. Will check it out on my boat. I have not noticed any issues with the engine missing - and I've never put a timing light on it.
1992 ProSport 205
(Former) 1989 ProStar 190 Power Slot
Smith Mountain Lake, VA
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