Plug wire routing

Reply Subscribe

Thread Tools

Search this Thread

Jul 28, 2009 | 07:48 AM

#16

NeilBittong

New User

Joined: Jul 2009

Posts: 6

Likes: 0

Is the firing order the same for a 1990 F250 7.5 L? Thanks

Jul 28, 2009 | 03:54 PM

#17

EPNCSU2006

Lead Driver

Joined: Nov 2002

Posts: 9,557

Likes: 44

From: Concord, NC

The 7.5 should have the 1-5-4-2-6-3-7-8 firing order

Aug 26, 2009 | 09:02 PM

#18

cmcolfax

Mountain Pass

Joined: Jul 2009

Posts: 178

Likes: 1

From: Richmond, VA

Quote:

Originally Posted by Old_Paint

WHATEVER you do, make sure that you don't run 7 & 8 side by side. I speak from experience, the engine will run like poop if you don't keep those two separated as long as possible. EVEN with new wires, you will get crossfire on 7 and 8.

:bump:

Looks like I will be re-routing some wires on Friday too...

-cmc-

Jun 25, 2015 | 05:25 AM

#19

walperstyle

Junior User

Joined: May 2015

Posts: 57

Likes: 1

Thank you for this information. I'm using the search engine but there is a massive amount of information. Thank you admin for organizing some of it.

Dec 21, 2018 | 08:09 AM

#20

CamoF-250

Elder User

Joined: Oct 2009

Posts: 534

Likes: 3

From: Chesapeake

Are there any links like these for a 92 5.8? I have never considered running wires next to each other may cause issues.

Dec 21, 2018 | 08:21 AM

#21

rla2005

Fleet Owner

Joined: Oct 2005

Posts: 20,787

Likes: 1,751

From: Kentucky

Dec 21, 2018 | 08:34 AM

#22

CamoF-250

Elder User

Joined: Oct 2009

Posts: 534

Likes: 3

From: Chesapeake

So you do want to run 7 next to 8?

Dec 21, 2018 | 10:22 AM

#23

Mikulh

Laughing Gas

Joined: Dec 2005

Posts: 904

Likes: 115

From: Laurel, MS

The problem is induced spark. Since 7 and 8 fire sequentially a spark in number 7 wire can induce a spark on the number 8 wire, which is getting ready to fire (i.e. has fuel mixture and is starting to get compressed), causing predetonation. The fix is simple... keep number 7 wire away from number 8 wire as much as possible. If they must cross be sure they cross perpendicular to each other...never run them parallel and close to each other.

Note. This is also true cylinders 5 & 6 of the new 302 firing order since they fire sequentially.

In the plug wire diagrams posted above notice how 7 & 8 in the old firing order and 5 & 6 in the new firing order are wired on the opposite ends of the wire loom to keep them separated.

FTE Stories

Ford Trucks for Ford Truck Enthusiasts

Every 2026 Ford Engine Explained

Brett Foote

10 Ugly Ford Trucks That We Still Kinda Love

Joe Kucinski

10 Things Every Truck Owner NEEDS (2026 Edition)

Michael S. Palmer

Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Verdad Gallardo

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Joe Kucinski

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Brett Foote

Top 10 Ford Truck Tragedies

Joe Kucinski

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

Brett Foote

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Michael S. Palmer

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Verdad Gallardo

Dec 21, 2018 | 10:42 AM

#24

rla2005

Fleet Owner

Joined: Oct 2005

Posts: 20,787

Likes: 1,751

From: Kentucky

The 5.8L EFI engine has always used the 1-3-7-2-6-5-4-8 firing order. There is no reason to separate 7 & 8 since they do not fire sequentially. Use the wiring diagram as illustrated, which is the official Ford method.

More information as to the reasoning behind it here: Spark Plug Wire Routing for '94-up 5.0L & all 5.8L

Jul 18, 2021 | 01:13 PM

#25

bountycrook88

New User

Joined: Jul 2021

Posts: 3

Likes: 0

For some reason my firing order is different on my 1991 f150 5.0

Jul 18, 2021 | 04:32 PM

#26

torq'ta 5 8

Lead Driver

Joined: Jan 2019

Posts: 5,080

Likes: 865

From: N.W. Alabama

Quote:

Originally Posted by bountycrook88

For some reason my firing order is different on my 1991 f150 5.0

Because yours is not a 5.0L H.O. it is 20hp less 5.0L engine, and different firing order.

Aug 18, 2021 | 11:37 PM

#27

TobyB

Laughing Gas

Joined: Oct 2014

Posts: 946

Likes: 186

From: Carnation, Wah

The cheat sheet:

do not run wires that are on sequential towers on the distributor next to each other.

t
can never find the right drawing when he needs it.

Aug 19, 2021 | 04:02 AM

#28

My4Fordtrucks

Hotshot

Joined: Jun 2015

Posts: 12,867

Likes: 2,440

Quote:

Originally Posted by TobyB

The cheat sheet:

do not run wires that are on sequential towers on the distributor next to each other.

t
can never find the right drawing when he needs it.

Save the picture from post #21 to your phone. Problem solved?

May 8, 2026 | 10:21 PM

#29

dremtofford

More Turbo

Joined: Apr 2018

Posts: 742

Likes: 59

From: pine city washington

how about the wires for an 85 f250 woth a 460 in it. the previouse mech had the timing 180 out and i am not sure of rthe firing order or wire routing.

May 8, 2026 | 11:59 PM

#30

AuroraGirl

Lead Driver

Joined: Jun 2021

Posts: 5,221

Likes: 805

Quote:

Originally Posted by dremtofford

how about the wires for an 85 f250 woth a 460 in it. the previouse mech had the timing 180 out and i am not sure of rthe firing order or wire routing.

Reply Share

First
Prev
2 / 3
Next
Last

Forum Jump