Firing order change on the A9L

[gadget73]

You can do head and intake, as long as its not anything hugely extreme. Cam changes will usually screw up SD tho because of the change in vacuum. Most other things are OK tho. Slight cam changes are also acceptable provided the cam is designed to work with an SD setup. They exist but there aren't a ton of them. An SD setup can be re-programmed with new fuel maps to account for a hotter cam. Mass air also isn't the Allmighty Oz of the EFI world either. If you get too far beyond it's pre-programmed fuel map it will also run stupidly. It is somewhat more flexible but it still has limits.

[turbo2256b]

Speed desity will get you more power than a mass air set up. You need the ability to map it yourself such as an aftermarket system like Electromotive. mASS air is just easyier in some ways. Had an Alpha Romero with a home made injection set up with speed desity had over 200 dyno runs and had it mapped fairly well. That little 4 banger would hall ass and corner like a dream. It was set up for short track road race. A real blast to drive more than equal to a modded Mustang in aa straight line and would leave them in a corner no prob.

[88grandmarq]

Dude! I'm paying attention! I was the one with the question!

Ever since I joined here, I have been led to believe that SD had no flexibility whatsoever without tuning. Everything in stone and shit, right?

Now you come along and rock my panther boat with your talk of easy SD modding! I was thinking about it all day! I couldn't wait to get home and read the responses in this thread.

Fuck it...you don't get anymore questions. :yuck: I'm going MAF!

ok.... let me try this again.

I am not saying you should or should not convert to MAF. I want you to understand how each different system works and clear up some common misconceptions people have.
SD relys on manifold vaccum to calculate engine load. Stock ECM programing requires a minimum of 17inches of manifold vaccum at idle, any less and the ECM assumes the engine is under load and starts dumping in fuel. Provided you maintain a constant manifold vaccum, SD can adapt to some moderate air flow increases with out sacraficing driveablity, provided you stay with in the limits of the fuel system.

larger throttle body, better heads, intake and exhaust have little effect on SD. My stock lo-po engine is runningand explorer intake, lightning EGR spacer and 65mm throttle body with out any problems at all. Scott's (lincolnmania) town car is running an HO motor, LSC SD ECM, 1.7 rocker arms, ported E7 heads, ported lower EFI intake manifold and a 65mm throttle body with no problems and excellent fuel economy.
Justin (phyazer5) ran E7 heads on his CFI motor with no problems.

Cam swaps become a problem for SD, most cams increase duration which deacrease valve overlap and drops manifold vaccum. The FRPP E cam makes about 13inches of vaccum when installed. An SD system will run on that, but will not be able to correctly calculate engine load and/or fuel maps.


MAF systems have their limitaions too and require they be tuned, to work optimally, if you want to use any parts out side of the stock Mustang MAF stuff.

[89GrandMarquis]

[QUOTE=Roach III]Is it possible? I'm not saying that it's the best idea for performance, or the best idea for anything, but I'm just curious if you can reprogram the A9L/A9P to fire like a lo-pro.QUOTE]

I would not recommend this mod. Here's a quote straight from the Mustang 5.0 Technical Reference and Performance Handbook (page 275):

The change [firing order change] was made to reduce loading at the number 1 main journal that occurs when the front cylinder on each bank (numbers 1 and 5) fires in sequence.

I generally figure that Mother Ford doesn't make changes just "because", and this makes sense to me.

So, for engine longevity, change the firing order.

[89GrandMarquis]

Ever since I joined here, I have been led to believe that SD had no flexibility whatsoever without tuning. Everything in stone and shit, right?

Two more quotes from the Mustang 5.0 Technical Reference and Performance Handbook:

An OE or mildly modified 5-liter H.O. motor equipped with a speed density system will outperform a mass-airflow system (on a comparable motor) in a wide-open-throttle operation. This is due to the speed density system's slightly leaner calibration and the lack of a restrictive mass-air-flow meter in its tract.

Generally speaking, speed density works better with an OE cam in a street-type 5-liter V-8s making up to 290 horsepower. In 5-liter V-8s modified to make over 300 horsepower, a mass-airflow system performs better in all-around operation.

Does this mean that a SD system (comparing an HO SD with an HO MAF) may give you better GPM? I don't know.

P.S. I put raised whites on my car in response to your pics - thanks for the inspiration.

[Roach III]

Generally speaking, speed density works better with an OE cam in a street-type 5-liter V-8s making up to 290 horsepower. In 5-liter V-8s modified to make over 300 horsepower, a mass-airflow system performs better in all-around operation.

Can't you put a bigger MAF tube on there? How expensive is that?

P.S. I put raised whites on my car in response to your pics - thanks for the inspiration.

Sweet mang! Thanks! Nice Marq. I know that 88 and 89 are good years for the Panther line.

Oh, BTW:

88Grandmarq, and Tom, I'm still going MAF.

If anyone wants a 91 LSC Mark VII computer (it's a D9S with the J5 port), make me an offer.

[Roach III]

No dude, for real (89GrandMarquis), that car is Haawt! Never really liked anything but TCs, but that biatch is ready to "put-out".

[89GrandMarquis]

No dude, for real (89GrandMarquis), that car is Haawt! Never really liked anything but TCs, but that biatch is ready to "put-out".

Actually, I thought that you TC is the best looking I've ever seen.

Anyway, we'd better stop fawning over each other, or else someone will suggest we get a room . . . .

[turbo2256b]

If you want to run a lopo cam on a 5.0 Speed desity computer all you have to do is switch 3 and 7 ...... and 4 and 6 injector pins on the wiring harness that plugs into the ECM. On carb motors all you had to do was switch the same terminals on the distributor. As for unloading of the #1 main your not going to see problems with 300 or less HP unless you add NOS. For any high HP 302 I would recomend the pre 78 blocks. The mains in those blocks are stronger. Also the cylinder walls are thicker.