Again, I'm not the first to do this. There is a guy in Florida who has done this on several of these cars. Go on youtube and search SC300 Megasquirt and you'll find a bunch of southern florida guys using it. His name is Jordan, and he calls his product "powersquirt" so you'll see that in the videos a lot.
The 2JZ uses VR sensors within the distributor. Both cam and crank. I am using the cam signal. I think I'm actually bringing both in, but I have USE CAM SIGNAL IF AVAILABLE checked in the program. Look at post 228 for how I wired it. The NE signal is supposidly the CRANK signal, and I'm using G2 for the CAM signal. I am tapping it so both MS and the stock ECU still see it. I tapped the signal on the wire that goes to the ECU (about 1ft prior to the ECU). The MS wire is shielded. I do not have the end where I tapped grounded though. I pulled back and heatshrunk the shielding on that end. The other end is the MS connector, and I'm assuming that end is grounded internally or something. I believe that's how it calls out to hook it up. Don't ground the shield on the "sensor" end, but ground it on the connector end.
Again I don't know much about MS yet, but here's my initial thoughts on why it also affects the cars tach. It is losing sync. Not the TS program, but actual MS is losing sync correct? Well MS is controlling the fuel and ignition. So if it loses sync, the fuel/ignition being output from MS for that split second is "bad", so the car is actually missing for that split second. You can feel it, you can even hear it in the video. It's not just the tach signal, the car is really actually missing when the sync loss happens.
Like I said, next week when I have time I'm going to pull the carpet back and resolder that connection, and ensure no conductors are exposed. Maybe throw some more tape on there. Also I may hook up the stock ignition again. So the stock ECU will still be controlling Ignition, and MS is only controlling fuel. See if that improves anything. I kind of wish I would have done that in the beginning. Just 1 at a time changes, makes troubleshooting so much easier
So as for MAPs. I've sent Jordan my MSQ file and he adjusted it and sent it back with a very "base" tune. That's the plan is he's going to help me get it running decent, but then I'll be taking it to Shane to get a real tune done, just want it running fairly decent as I don't want to give Shane an untuned mess that he has to start from scratch on.
Yes I know I can switch to COP with MS3x. But like I said, I'm trying to do 1 at a time here. I plan on keeping the stock dizzy for now. In the future I may look into changing that, but for now, 1 thing at a time...
What system are you running? MS2, 3, etc? I'm working on making myself a custom dashboard in TunerStudio. You got any cool dashboards I could see or use? I like that default Green one that you see in the video that came with TS, but I'm going to make something with histographs so I can watch actual logged AFR vs. Target AFR and what not. And only throw gauges on there that I care about.