First power up of my Megasquirt MS3-Pro

This weekend I wired up all the sensors and power for the ECU. I spent a bunch of time matching up the wire colors from the old Thruster ECU to the new Megasquirt.

The ECU powered up and all the sensors had valid readings. Now I need to finish the wiring for the fuel injectors and the HEI ignition.

Mounting my MS3-Pro ECU

I made a mounting plate for my MS3-Pro out of some scrap acrylic I had laying around the garage. I also mounted the relays and fuses for the ECU and fuel pump on the same mounting plate. I made a couple stand-offs so the fuse holders sit up above the relays making it easy to get access to the fuses if one needs to be changed.



Here is the ECU mounted inside the truck.

New mounting bracket for my remote HEI coil

After reading the manual for the Megasquirt MS3-Pro and some forum posts on msextra.com I realized the way I had my remote HEI coil mounted it was probably causing a lot of electrical noise (EMI). I did two things with my original coil installation that should be avoided. First I had a long coil wire that ran parallel near other power cables and second I had long power wires running to the coil. To clean this up I made a new mounting bracket that would allow me to mount the coil near the distributor and in turn reduce the lengths of the coil wiring plus move the coil wiring away from other wires that might be sensitive to EMI. I drew out a design on some 16 gauge flat steel and cut it out with a cutoff wheel on an angle grinder. I made a few bends and welded on a couple gussets to stiffen it up.


Next I made a small mounting plate and welded two bolts to it. The mounting plate will go on the inside of the cab and the thread will protrude through two holes drilled in the firewall. Then I spray painted it with some gloss black paint and let it dry overnight.


Finally I mounted the bracket on the firewall and shortened the coil wire.

Dumping my Accel Thruster EFI ECU - Part 2

In my last post I discussed why I decided to dump my Accel Thruster EFI ECU and switch to a Megasquirt MS3-Pro. As I began removing the Accel wiring harness I discovered some troubling things stuffed inside the tightly wrapped convoluted tubing. When I started peeling back the wrap from around the convoluted tubing I first found a damaged ground wire on the ECU power relay. Most of the strands in the wire are broken. If this wasn't causing some of the problems I was having with the system before it would certainly have been an issue once I was able to drive the truck. Once things started jiggling around as the truck went down the road this would have certainly broken off completely in a short amount of time. Half an inch more of heat shrink tubing would have helped avoid this wire from being bent right at the connection. Next I found a power wire with exposed bare wires which could cause a nice short circuit, especially with ground wires breaking off in the harness. Again an additional half inch of heat shrink would have prevented this. Shame on Accel for this. I suppose it is just cost cutting on their part but we are talking about pennies worth of heat shrink tubing.

Broken ground wire

Exposed power wire

As I got further down the harness I discovered another gem. The harness contains a connector that lets you interrupt the ECU from controlling ignition timing and lets the HEI module just uses static timing. This is useful for setting the initial timing but most of the time it should be connected so the computer can control the timing. The connector was wrapped up in plastic tape and when I unwrapped it I discovered one end of the connector was completely missing it's housing. Without its plastic housing the pin inside the connector could easily fall out. I'm sure that would be a real head scratcher if fell out and the engine suddenly had no power.

All of this is making me more confident about my decision to pull out this Accel Thruster ECU.

Dumping my Accel Thruster EFI ECU for Megasquirt

It's been while since I have written a decent post for this blog. The main reason for that is I have been fighting with my Accel Thruster fuel injection system for quite some time now. I got it to the point where the engine would start and run for a while but once it got up to temperature it would stall. So I began a quest to try and find some help. I searched all over the internet trying to find a forum with other DFI users and found none. I tried to find more documentation but Accel's website is absolutely horrendous. Just terrible. I almost can't express in words how awful it is. In contrast FAST and Edelbrock have fantastic sites. So it's not like an old school hotrod parts company can't put together a decent website. After giving up on Accel's website I attempted to try and contact Accel support but they have ZERO internal support for their fuel injection systems. They recommended I contact a third party who they consider a 'master installer' for support. I did contact this person but after exchanging a dozen e-mails I didn't feel like I was making any progress. The documentation I was able to find for this system was confusing at best and terrible at its worst. It seemed like the documentation was assuming more knowledge than I possessed which I guess is on me but when there is no where else to turn for help it is a really shitty situation for me. I also could not find any online forums with other Accel Thruster EFI users.

I purchased my engine from a builder who was supposed to tune the fuel injection system on their dyno and give me a pretty much plug and play setup. I'll admit I am a novice when it comes to EFI systems. Maybe I was expecting too much from 'plug and play'. After fighting with this Accel Thuster system for months and getting advice from knowledgeable friends I slowly began to realize this Accel system was not a good fit for me. I wanted something that was initially ready to go but I could learn more about and tweak later on. After doing all this research trying to find support I now think that Accel EFI systems are marketed at engine builders and are not for hobbyists like me. The lack of support, lack of online communities and lack of decent documentation makes it very difficult for the average shade tree mechanic to work with this system. Their Thruster tuning software hasn't been updated since 2009 which is concerning because entire operating systems have come and gone in that amount.

A friend of mine recommended I read a book titled 'Performance Fuel Injection Systems' by Matt Cramer and Jerry Hoffmann. It was very informative and covered a wide variety of EFI systems from full aftermarket to piggy back units. My first realization from reading this book was that the narrow band O2 sensor that came with the Thruster was essentially useless. I purchased a PLX Wideband O2 sensor and attempted to use it with the Thruster system but it didn't help me narrow down any of the issues I was having.

After reading about the capabilities of various systems in the book I decided to learn more about Megasquirt ECUs. Megasquirt seemed to have the most features for the best price. I was especially interested in the CAN bus capabilities. I downloaded the manual for the MS3-Pro ECU from diyautotune.com to learn more about it. The manual was easy to understand and didn't seem to assume much if any prior knowledge about EFI. Looking around the internet for online support I found the Megasquirt forums to be very active. There are a bunch of helpful videos on Youtube too. ExtraEFI has a series of video tutorials that go through every single menu option of TunerStudio and explain what each setting does.

I felt now I could make an informed decision what I should do. I definitely wanted to stick with EFI. I wanted a system that could data log internally (Thruster EFI can't without an expensive add-on). I wanted to run dual O2 sensors and have each data logged (Thruster only supports one O2 sensor input). I wanted to be able to control three separate electric fans (Thruster only supports two). I wanted software that could run on Mac or Windows (Thruster is Windows only). I wanted a modern system that was under active development and has an online user community (Thruster seems like a forgotten, stagnant product). All of this was pointing me at a Megasquirt system. I decided to go with the MS3-Pro ECU.

The Megasquirt manual had some great advice on wiring ground connections and how to reduce EMI noise reaching the ECU which could cause erratic behavior. These things may well have been some of the issues with the Thruster system but their manual made no mention about this. I am working on relocating my HEI remote coil to reduce noise from that and I have to wire up all the sensors to the new ECU. I'm planning on writing up blog posts to document my experience of installing this Megasquirt system. Hopefully it will be much less painful than that damn Thruster system.

Removing the connector on a GM / Bosch style fuel injector

I could not figure how to remove the electrical connector just by looking at my fuel injectors. I didn't want to break the connector or injector so I went searching google. I found the answer buried in some random forum. That forum post also had some bad advice which if followed would lead to a broken connector. So I thought I would document the correct way to remove the connector with some detailed pictures. The most important advice is do not try to pry off or otherwise remove the metal clip. This will lead to a broken connector.

Here is how to correctly remove the electrical connector from a GM style fuel injector.

This metal wire is the retaining clip that holds the connector on the fuel injector. Pressing up on it releases it.

Place the tip of your finger on the metal clip.

Push up on the clip with your finger.

While continuing to press up on the metal clip, pull the connector away from the fuel injector. It may be easier to do this with two hands.

View of the removed connector.

Showing the metal clip being depressed on the connector.