but they are aging. And with that age, the capacitors and other electronic components get more and more worn.
This is my gripe with all PNP systems, since they also rely on delicate factory sensors and modules to do their job. Fortunately you can get a drop on harness from Stinger that replaces the whole factory engine harness, so that is a plus (holley does this as well).
I'm more of a fan of the coil-per-plug ignition systems so I'm using LS coils on a SBF, which you can also do with both Megasquirt (Pimp and DIY variants), and Holley.
As far as comparing the two, I've tuned a few dozen megasquirted mustangs and am also tuning on a twin turbo dart 427 mustang with a holley dominator system (first time for me).
The tunerstudio software used for tuning megasquirt is better in my opinion. It's more intuitive, better sorted, and seems to provide better physical control of tables/variables within the software.
Holley's software hasn't been as intuitive and granular but the ecu itself has this pretty nice ability to just work
. It's a much easier system to tune for people with limited experience tuning. As long as the widebands are installed and the sensors are calibrated, the car pretty much always cranks right up and runs, even using a base tune from a car that isn't very close. It has some pretty gnarly correction features that keep it safe almost regardless of what's in your fuel table. The "auto-tune" (fuel table only) feature is pretty effective. We took this car (1400hp supposedly) to the track on low boost and a base tune from a different combination. I adjusted a few things before the first pass to make sure it was safe, then within 4 passes the fuel table was dang close and we were able to start throwing timing and boost at it. He also street drives this car over 50 miles at a time and hasn't had many issues with it whatsoever.
Having said that, I'm also tuning a single turbo LS mustang on methanol
with a mechanical fuel pump and standard port injection on MS3Pro. The freaking thing started right up after I created the base file and guesstimated some tables/enrichments. Everyone told us it'll never start on meth, blah blah but it does. Nothing like those old alky blower cars that have to have a shot of gas down the hat to fire up. We will be treating this car similarly to the twin turbo 427 holley car.,where we get it to the track and try to get it running well in one night, so this will be a great Head-to-Head comparison of how well both systems perform for the modern drag racer.
The megasquirt systems have more variables to look over before the car can start and drive. You have to be a more knowledgeable tuner to make a megasquirt system work really well (in my opinion) but that's also a plus in my book.
All this to say, as an engineer who is eager to learn as much as possible about calibrating and tuning, I prefer the megasquirt systems over holley BUT I am definitely impressed with how easy and effective the holley dominator ecu works for the person with limited knowledge or less time.