Okay guys, after five years I'm thinking of going to full engine control instead of just running fuel-only.
The reason why I never went to ignition control is that I have always had a jumpy RPM signal. I never really cared all that much because it didn't affect fuel too much, and being a rotary, it really doesn't care inside a remarkably wide window.
But if it needs that signal accurate to control timing, suddenly I care about it. Here's a second gear pull for demonstration. (AFRs go pig rich when the injectors stick open at the top end, it happens)
Could this just be because I'm using a 1.01 board and they weren't that stellar? Ignition control will be on a 3.0 board.
1.01 boards did need some mods for a smooth tach input, if you look at the differences between that and the 2.2 they're apparent.
I have never had a problem on a v3 that I couldnt fix on the input side.
I know nothing about magic spinning triangles, how do you pick up the rpm signal? I've never used a v1 but all of the version 2+ I've been around were fine
If you need a reliable rpm signal why not use a crank trigger to measure rpm?
Paul_VR6 wrote:
1.01 boards did need some mods for a smooth tach input, if you look at the differences between that and the 2.2 they're apparent.
I have never had a problem on a v3 that I couldnt fix on the input side.
That's good to hear. IIRC, I bought this box from you five-six years ago.
This is reading from the distributor but the signal is coming from the MSD's tach output, which is supposed to be a really good square wave. If/when I go with ignition control/3.0 board, it'd be with a 30-1 wheel.
Knurled wrote:
This is reading from the distributor but the signal is coming from the MSD's tach output, which is supposed to be a really good square wave. If/when I go with ignition control/3.0 board, it'd be with a 30-1 wheel.
In that case, the RPM signal will be coming from a totally different source, so the variation in the signal you see now should be a non-issue.
Could be, I have sold some older units here. john and/or Wing diodes might help.
Agreed w Matt if you ho crank trigger/v3 its all different.
I'm not concerned with making this one happy. Once it is done being fuel-only on this car, it will be rotated to being fuel-only on something else. Why reinvent the wheel? 
Knowing that the RPM fluctuations are an issue with the particular board and not the system in general is a large confidence boost.
I had been thinking of MS3X for a third car, but gosh, I can get a FAST XFI for a tiny bit more, once you get all the bells and whistles.
Knurled wrote:
I had been thinking of MS3X for a third car, but gosh, I can get a FAST XFI for a tiny bit more, once you get all the bells and whistles.
Was there any feature the XFI has that you needed that an MS3 doesn't have? (Yes, I'm not exactly neutral, and could very well see if I can get them into the MS3 feature set...)
MadScientistMatt wrote:
Knurled wrote:
I had been thinking of MS3X for a third car, but gosh, I can get a FAST XFI for a tiny bit more, once you get all the bells and whistles.
Was there any feature the XFI has that you needed that an MS3 doesn't have? (Yes, I'm not exactly neutral, and could very well see if I can get them into the MS3 feature set...)
We're a FAST dealer. That helps
I need 5 coils and injectors, boost control, and rock-solid knock sensing. I'd like to be able to have three or four different maps available to me, with at least one "dead" map for theft deterrence.
If you're interested in MS3-Pro, contact us at websales@diyautotune.com and we can get you a dealer account for that too. 
The features you listed are all straightforward enough in MS3.
MS3's knock sensing is a bit more sophisticated than XFI's (according to the documentation I was able to find, at least - correct me if they've improved it). The XFI appears to only use a GM ESC module, which is tuned for a specific engine and I believe just puts out a signal when the intensity on its target frequency goes over a preset level.
MS3 can use a GM ESC module, but it also lets you wire a knock sensor up to the MS3 directly and use several features not available on FAST:
- You can tune the knock frequency in the software.
- Threshold levels can be set separately for each cylinder, for engines where not all cylinders are equally loud.
- You can set it to listen for knock only during a specified crank angle, letting the MS3 ignore noise coming in at any other time.
- The intensity level can be adjusted as a function of RPM, to compensate for RPM dependent changes in the background noise level.
