only half the motor firing? wtf?

[Chuckman]

got my explorer motor running in the stang, and im having problems. its missing something fierce, putting a timing light on every wire shows that cylinders 3,4,5, and 7 arent getting spark. ive moved the plugs and wires around to the working cylinders, and the miss does NOT follow the plugs, nor are they soaked in fuel/oil/etc, when i pulled them out they looked brand spanking new, no heat discoloration at all. i just pulled my 24# setup and threw in my stock 19#ers on the off chance that the injectors were stuck open and drowning the spark (cars been sitting since august, and only ran for a couple months then after being down a year). no change. however, i can pull a plug, keep it on the wire, and it'll spark on the upper intake no problem.

any one have any ideas? things to test/check/change?

 

[jrichker]

What is the cam you are running?

What computer are you running?

This doesn’t prove that the block is a HO block. Some trucks evidently use a HO firing order
with a low lift cam. However, it will definitely prove that a block can’t be HO because the firing order is wrong.

Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

 

[Chuckman]

cam is a tfs stage 1, and the comp. is the stock '89 5.0 auto unit. basically, my old motor self-destructed, and i grabbed a gt40p motor, changed the cam, and put my tfs street intake on it.

im going to double check the firing order, i could swear the ford shop manual gave me the 1-5-4 one.......


EDIT: AH-HA!!! the manual does give the 1-5-4 order, but if you look at drawing over it, its the 1-3-7. thats one hell of a typo.