PiMPxs Non H.O. 5.0 Questions

[86mgm]

Hello,
I am the owner of a 1986 Mercury Grand Marquis that I am slowly working towards modifying. My eventual goal is to make something kinda like an 80’s version of a Marauder, but while retaining most of the 80’s “luxury” vibe that I like so much.

My plans are eventually to swap in a different engine, probably an Explorer 5.0 with the H.O. firing order. However. I am currently rocking the original LoPo 5.0 and have been struggling with the symptoms of capacitor failure in the factory ECU. Now while I could replace the capacitors, and I probably will in the meantime due to money being tight, I have been looking for a suitable replacement. And while a remanufactured ECU might fit the bill, it would have to be changed again in the future when I install the other engine.

Plus all of the factory ECUs, whether for my car’s current engine or an H.O., are 30+ years old at this point and, while I am a lover of vintage electronics, I would prefer to replace a part this critical to my car’s function with new, quality hardware.

This brings me to my questions:

• Can the PiMPxs run a LoPo 5.0?
• If it can, would this allow me to make some small, bolt-on, modifications to the current engine? Things that could be transferred to an H.O. based engine in the future, such as headers or and Explorer intake.
• Would anyone be able to offer turning advice since it seems that no one has run the PiMPxs, or any MegaSquirt based ECU, on a LoPo before?

The main reason I am even asking is because I see no reason to spend money on a factory ECU, only to replace it again down the road, if the PiMPxs can run my engine in its current state; and then with a different tune, handle the engine I intend to build in the future. Plus I admit, I am kinda curious to see if it can be done, and if a custom tuned LoPo is in any way better than a stock one, be it in power or economy.

Thank you,
Scott Williams

[Stinger]

-Yes, because it's batch fire EFI anyway so firing order doesn't matter for the injectors (it's going to fire 4 injectors at a time regardless).
-Yes, it will allow all mods, now and later. Stock or 1500hp or anything in between.
-Tuning is no different regardless of whether it's LoPo or HO. With that said, we have hundreds of "LoPo" truck customers here as well so it's certainly nothing new.

[86mgm]

Thank you, good to know.

I admit I was under the impression the Panther chassis cars were sequential like the H.O.s, as there are no wiring modifications needed to install an H.O. engine, just the H.O. computer, but I am very likely to be wrong. I would prefer to have it be sequential injection. A big goal is to keep or improve upon the factory fuel economy numbers. In any case, thank you for the confirmation that such a thing would be possible. I didn't even think about the similarities between the truck and the LoPo, probably due to the differences in the injection systems and intakes. Now to save up for the ECU.

Scott

[Stinger]

Searching around it appears they are sequential. Most of the other non-Mustang LoPo applications are batch fire in that era so I assumed that was the case with these as well.

This is from the PiMPxs FAQ:

Sequential V8's needs to use the HO firing order of 1-3-7-2-6-5-4-8 which connects like this (which coincides with the A9L/Fox Body pinout):
Inj 1 = Pin 58 = A
Inj 2 = Pin 59 = D
Inj 3 = Pin 12 = B
Inj 4 = Pin 13 = G
Inj 5 = Pin 14 = F
Inj 6 = Pin 15 = E
Inj 7 = Pin 42 = C
Inj 8 = Pin 52 = H

The ECU is configured for the "HO" firing order so if your engine uses a non-HO firing order then this needs to be accounted for. This only applies to sequential applications, batch fire is fine regardless of firing order (as previously mentioned). Firing order is set by hardware. The firing order parameter in the ECU only determines which trim table applies to which injector driver. The injectors fire A-B-C-D-E-F-G-H in order. Since our ECU's are always pinned out for 302HO/351w firing order, non-HO firing order actually requires moving pins around in the harness to account for this

Which would be the same pin changes as what would be required to install a Mustang HO computer like you mentioned above. Pin changes don't require cutting any wires, it's a non-destructive and reversible process.