MS Switchbox MS or Stock ECU (U PICK)
 

Built my switchbox which essentially replicates the same mods that Kingofl337 did but externally. Making it a relatively easily reversible mod vs. drilling and cutting the stock ECU internals. It does weigh more, it does take up more space, and it does take a bit of time, but i'm happy with it.
I have 3 switches, one for Fuel, one for Spark, and another for idle so I can tune idle later on for the 550s without having to get way under the dash again to hook that up. Ideally i'll be able to install MS and leave it in there though Im sure sometime i'll be taking it out for some kind of rev lights, launch control, WI, boost control, or w/e my heart desires and has thoroughly planned out. I'll post the wiring schematic for this unit with the stock wiring colors when i know they are correct.

Still have to loom it all up and get it routed in the car but this is the bare setup shown.

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PS. For those of you other '99 owners that have your stock ecu under the driverside dash. Man it sucks being us, those who have the ECU behind the passenger seat or in the passenger floor board are rollin fat and happy in comparison.
Also if this looks like alot to you, it is. If you see the 5 wires going to the MS, If you were to cut them off you would be tieing them into the stock harness alone. Everthing that's black and not connected to the MS directly, is the extra wiring for the switchbox.

Thats an awesome looking box. I need to get around to makeing one of those. My switches are flopping around in my dash were my airbag used to go. What switches did you use? The blue looking ones form radio shack?

Where did you end up mounting the Megasquirt case? I mounted mine vertically against the right V-shaped dash support just in front of the gas pedal. Not perfect but not bad and my foot doesn't hit it even when the serial cable is plugged in now.

What did you pay for those switches? I payed around $15 for the 4PDT switch through Digikey. Thats way too much money. If there's a cheaper option i'd like to know.

Smart including the idle control. I wasn't worried about it at the time but I'll need it eventually.

I used one blue DPDT switch from radioshack for the idle control, $3.99.
The others are 4pdt on-on switches.
I needed one 4pdt switch for fuel because you have the 4 single injector inputs becaue the 1.8 uses sequential injection i believe, i then jumpered the inputs from MS for the two banks of injectors for batch injection. For spark all you need is a DPDT switch though, the other two poles go unused.

I'm going to mount the MS right on top of the stock ECU hopefully otherwise I'm going to be extending alot of wiring if that isn't going to work for me.
Then the switch box will be installed against the driverside wall of the car, basically on the inside wall of where the door hinges are.

I paid around $3 or $4 for the switches a piece and they combined shipping as an ebay seller. They were cheapest on ebay and shipping was fast.

I'm hoping the Idle control was a good addition and I didn't forget anything else. If it doesn't work i'm gonna be bummed cause it'll be a pain to troubleshoot it.


I also just realized I have an autocross this weekend i wanted to attend. I already un-installed my voodoobox so the car is currently not in turbo friendly condition. Thinking i might reinstall the Vbox and just datalog with for a bit while i get my MS settings sorted out and see how well i can get the vbox tuned because i'm not super happy with the AFR's the box produces sometimes in comparison to what i've seen with the PC-Pro awesome flat AFRs. Might be good information to be able to give prospective Vbox buyers and for my own personal curiousity because no one really seems to know much about them at all.

why would you need such a thing?

So i can tune fuel while still running spark off the stock ecu. Then switch over to tune spark. Then once I have all that figured out and going well i can switch idle on so i can tune idle with the stock injectors so I know that's working. Then swap in my 550cc injectors and run with the new found ability to max out the efficiency of my turbo.

The box also helps if for some reason something is wrong with MS or something in your tune is wrong you can switch back to the stock ECU and limp home.

Just as a heads up, I was running MS controlled spark and ECU controlled fuel for a couple of weeks to debug a hard starting problem. Turns out that my MS was coming on-line several cranks cycles after the stock ECU was dumping fuel even with delay cycles turned down to 2. This was causing the hard starts. Turning over to MS controlled fuel+spark fixed it, although it does take more cranks to start up. This might be unique to my system, though.

Limp home mode kicks ass.

cj, I just finished building and modding my board tonight ... gonna try to get the harness adapter together tomorrow (boomslang'd). I wont have any switches though, just one ecu or the other, so my limp home mode will be plugging in the stock ecu. Will be hard to "limp" home with 550 cc injectors :) I got some too that have been sitting for months waiting to be in my car.

Hey, so how is your car doing now?

Nice. I ordered the boomslang connector today. Screw the switch box. Once i remove the MAF and put in the 550s my limp home idea will be worthless anyhow. Spent about 2 hours today repairing the stock harness that the previous owner had destroyed. I found out my problems were arising from wiring he had messed with at the ECu connector, 1 of the wires had fallen apart completely, so on and so forth. I got it fixed, and did it the best/strongest way I could. I'll never modify a stock harness again unless i have to.

eh sounds like no biggie. I tried a MS install without fully understanding it last fall, but I had issues that could not be resolved with my limited understanding. During the megasquirt install, I was so confident it would work that I cut the original harness off completely. After I couldnt get MS to work, I bought a TB and ECU wiring harness from an AT '90 and put those parts on. I am a bit more knowlegablele now, so i hope it works out this time around.

Anyway, im not gonna say anymore lest I jinx myself lolz
- ryan

Yeah i thought i knew alot more than I did. My balls have shrank a bit in the past few days from me kicking myself so often.
Turns out all I need is one transistor to replace the Q8 i removed, I have an extra one that was supposed to be installed in Q20 but i left it out. So I can install that in place of the removed Q6. Everything else is fine though.

What MSQ are you going to try and run first?

ill be using 029v

I'll be using 029v or later, by msq I was talking fuel/spark maps and whatnot not the actual firmware on the MS.

ill tune fuel myself and copy Als map for timing. I got a wideband so getting a decent tune should be rather easy.

Be sure to share those maps cause I don't have a WBo2 ;)

My problem right now is that I cant get the cas to trigger RPM, i cooked the processor on the stim with a walwart, but i get an rpm signal by flipping the stims rpm switch on and off. Tried hooking up power, grounds and the two CAS wires on the car last night and got no RPM while cranking, then I hooked up my Grandpas OLD Oscilloscope (for television repairs) and tested the two wires while spinning a spare cas by hand. For some reason, there was a definite 2 to 1 square wave coming out of the yel-blu? wire, but i got nothing from the white one ... oh well ill check it out more later today.