My illumination on Firing Order for 5.0 HO

[Fox Body]

Okay, on my new '92 GT, I just finished changing the cap and rotor, cause I checked it and decided it would be a good idea to change them. Now, I am always careful to take one plug wire at a time off the cap and transfer to new one till they are all changed then just switch out, instead of learning the firing order and starting from scratch each time.

SOMEHOW, this time, my mind strays for a second when I'm am putting on the last 2 or 3 and after I'm done, something hits me. "Oh, oh. Wait a minute, that doesn't feel or look quite right." To make a long story short, I find myself all screwed up. So I look up the firing order for 5.0 HO and find it is 13726548 and that the older 5.0s and a couple of newer ones are 15426378. Okay, mine's is clearly the first one and so I start to redo it and noticed that it still definitely didn't look like the order from which I removed them. I did a little retracing by hand and I'm not 100% sure, but I am at least 98% sure that it whoever messed with it b4 I had it wired it in the old order (15426378). The reason I am so sure that it was 15426378 is b/c take a look at the 2 orders:

#1 13726548
#2 15426378.

When I checked and then reordered them to 1376548, I notice that most of them were correct, but some (I remember it being 3 and 7) were not (can't remember how 5 and 4 were but it HAD to be in the #2 order.

Now I checked around and found this:

"Another thing to remember when doing an EFI conversion is that there is 2 different firing orders for small block Fords. Early 289's, 302's and some late model 302's run the 15426378 firing order. Late model 302 HO's and 351W run the 13726548 firing order. Installing EFI on the 15426378 firing order is possible, but does not yield the same results as the late model HO firing order. When you mix, match these firing orders you may encounter some driveability problems like poor idle quality....." http://www.ronmorrisperformance.com/06tech/

I have noticed that the car felt a little sluggish and even posted a thread about the car trying to die on first crank after sitting for a long while. But I would figure a mismatched firing order would be a LOT more noticeable than that. Even if it could work. Now I'm not 100% these problems are totally related, but it seems they certainly could be. I think the best way for me to test it would be to reorder the wires on the distributor and crank it up and if it idles fine, take it down the road and see how it runs, then reorder it back to 13726548 and compare the diff. I am kinda frustrated (but relieved I got it back right) and dont' really feel like messing with it now. Maybe I'll do that later this week. Can anyone confirm/compare driveablility b/t the 2 orders??? Maybe this will save me the task of finding out myself.

Okay, I took it out on the road and got down on it. Now I gotta be honest, you know how if you do a little mod on your car like Al driveshaft or cold air induction or whatever and intellectually you know it shouldn't make much of a diff hp-wise, but emotionally, b/c you want to believe that you've added hp, you will somehow think "Hmmm, I can feel a diff now" . Well, when I took it on a drive, it seem to have less sluggish acceleration and was running up the rpms more quickly. Cruise speed didn't seem any different but acceleration did --- a tad bit. Well, I figure I'll drive it around more and see if I can tell any more of a diff.

Like I said b4, I am always VERY careful when I change the cap so I don't have to waste time and retrace each plug wire, but I gotta thank God for allowing me to lose my train of thought this time. What I figure is if I had not lost my train of thought for a few seconds and screwed up the order, then I would have never found that it had been wrong in the first place and wouldn't have had to find the correct order and fix the problems. I am certain it was different b4 than it is now that I've corrected it, whether it was 15426378 or not. I am certain it was not 13726548. I'm still a little puzzled as to why more pronounced symptoms didn't show up earlier....

Thanks for listening.