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

 

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

 

:bump:

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



-cmc-

 

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.

 

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

 

 

So you do want to run 7 next to 8?

 

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.

 

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

 

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.

 

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?