My Megasquirt adventures over the years

Fast forward a few years and I was looking for the next project and things to put on a Christmas/birthday wish list, so I had the idea to upgrade my MS2 setup to an MS3X so I could run the ignition and get all of my tuning in one place vs having to tune the fuel and ignition separately. I got the parts for Christmas and the big redo started a couple of winters ago. I pull the whole harness out of the engine bay and started fresh as I was going to be adding quite a few new things and I had a nice fuse/relay panel I got from work to make things look a little better. I also had a scrap harness from work I could salvage wires from. The biggest challenge was figuring out what all the OEM connectors were as I did not want to do pigtails and splices for everything, but real crimped connections. I managed to track them all down and made a big spreadsheet with all my circuits and the part numbers for the connectors, terminals, seals, etc. for future reference (happy to share if anyone is looking for any particular connector). I also took this opportunity to drill some new holes in my firewall to run bulkhead connectors for all of the new engine wiring instead of passing it through a hole with a grommet like I did before. One connector is dedicated to power (so things like injectors, coils, etc.) and the other is for sensors and signals. I also had to grab a set of spark modules as the MS can't run the Hemi coils directly. I made my ignition table by copying what was in the MSD at the time and got it all back on the road and running again. It seemed to run a little better with the sequential injection now, and having a real spark table was nice compared to the old MSD setup of an rpm curve and a vacuum curve. The MSD was basically a 2D + 2D setup, which isn't quite the same as a real 3D table. While it did seem smoother for fueling, I felt like I lost some get up and go in the conversion as well. The main issue I had initially is that the car couldn't even drive in 6th gear on the highway. It just had no power, but it would do okay if you dropped down to 4th or 5th. This started my quest for timing tables as I tried several. I found some OEM ones, but I had a hard time understanding the best way to use them and there was all sorts of confusion about the numbers on them throughout the internet since they were so low compared to typical engines. It also doesn't help that there are multiple tables (like MBT and WOT varieties). I tried doing a blend of the two originally, pulling WOT table values for anything above 80% load or so, but the car just really didn't like that much. I don't recall exactly what I settled on at the time, but I think I basically just ran the MBT table and pulled some timing from the top as a safety blanket.

I was also starting to look more fully into closed loop idle control as my electric fans put a noticeable strain on the engine at idle and I wanted to be able to adjust for that. That was basically a lot of guessing and checking, and I eventually got it working "good enough" for the time. It would settle okay and bump up the idle a tad when the fans came on so at least the car didn't want to die. I had some spare inputs on the new computer as well, so I decided it would be fun to a add a front wheel speed sensor so I could have traction control. Since I was going through that trouble, I also figured I might as well have launch control, so I looked at ways to get an input from the clutch for it. The main thing I wanted was some tunability in the switch point as the old MSD setup was just a button for the rev limiter, and if you let go of the button before the clutch started biting, the revs would climb too quick and shock the tires like a regular clutch drop. I was originally trying to figure out how to get a pressure switch in the clutch line so I could set a trigger based off of pressure, but I couldn't find a nice way to do it that didn't take something silly like three different fittings to adapt things, so I ended up putting a potentiometer under the dash with a string to the pedal. It actually seems to work pretty nicely and gives me the tunability I was looking for. So now I had everything working pretty nicely again, but my O2 sensor was getting really weird with me. It was an older Innovate LC-1 unit and I had found the software to adjust settings on it and flashed it to a newer firmware and changed some response rates on it looking for better performance, but I think my sensor might have been going south. It was probably 15 years old at this point, so maybe not that surprising. Since I had been messing with adding CAN bus functionality to my car, I ended up getting a 14Point7 Spartan 3 v2 to replace it. It can run either via CAN or traditional 5v output, so I was covered either way. I liked the idea of CAN as it would reduce the chance of any kind of signal interference on an analog line.

Somewhere along the line I also finally managed to track down a knock module to add to my install so I could have knock control. I had been waiting for DIYAutoTune to start selling them again, but they had been out of stock for years and there was no word on them coming back. I found the chip they were using on the board and debated trying to reverse engineer the module myself, but luckily someone had already done that and was selling them on Ebay for the same reason (they were fed up with them being out of stock). I still had the OEM knock sensors on the engine so they got wired up and the switch flipped in the software. I didn't really tune anything at the time because it sort of seemed to "just work" with the default settings, though there was no really easy way to tell without trying to trigger them, which I was hesitant to do given the fragility of the ring lands on the pistons. The knock sensor output numbers on the software seemed to be reasonable though, so I just kind of left them there.