VVT observations - current vs. advance
#103
mkturbo.com
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/admin.png)
iTrader: (24)
Join Date: May 2006
Location: Charleston SC
Posts: 15,189
Total Cats: 1,685
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Ok I will gladly be first in line to give him my money in exchange for the controller.
kcbhiw
What type of program are you using to set up the timing table and everything? Also how easy is this going to be to integrate with my megasquirt. Will I have to switch between the 2 programs to tune spark and fuel?
Also any chance that it is ready by May?
kcbhiw
What type of program are you using to set up the timing table and everything? Also how easy is this going to be to integrate with my megasquirt. Will I have to switch between the 2 programs to tune spark and fuel?
Also any chance that it is ready by May?
#104
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
For the time being, you will have to switch between my application and whatever you use to tune your MS. That will hopefully change down the road, however.
Integration with your MS is straight forward. You will have the ability to use it either strictly as a standalone module or pass-through where NA CAS or NB2 trigger outputs are emulated and sent to the EMS. I'm currently using the CAS emulation in my car. There is no other interaction with any EMS aside from that.
My goal is to have it out soon. I know I keep saying that, but I want it more or less perfect before it goes anywhere.
#106
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I would need more than simply RPM from an EMS as I need to caluclate actualy camshaft advance in relation the crank. Timing IS critical here.
#109
mkturbo.com
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/admin.png)
iTrader: (24)
Join Date: May 2006
Location: Charleston SC
Posts: 15,189
Total Cats: 1,685
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Yah let me know about the Beta run. I am looking at the beginning of May to have my new motor built and installed. Will be looking for some way to control VVT after that until MS3 gets built in support.
#111
mkturbo.com
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/admin.png)
iTrader: (24)
Join Date: May 2006
Location: Charleston SC
Posts: 15,189
Total Cats: 1,685
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I plan on putting on the VVT and either running an rpm switch or leaving it disabled until the VVT controller is done. My pistons just came in yesterday, so next week I hopefully take stuff to the machine shop.
#113
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I'd likely be a good tester, but, I'm whiny. :-) You certainly have more convincing to tell me that the accuracy of the spark timing has more error in it than cam timing. MS-II has a (rudimentary) cam phase as a reported value. And I'd rather be 1* off in cam timing than spark. How do you know that time it takes to get the signal out is conserved?
#114
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
If you have an NB2 I expect that Kevin's circuit will simply share the crank and cam signals with the ECU. If you have an NB1 I think the factory ECU can accept the VVT cam signal as is. (the crank signals are the same)
If you have an ECU that expects NA style cam and crank signals, his controller will output NA style signals derived from the NB signals. This should be more accurate than an actual CAS because he derives the signals from the crank, in a similar manner to how ECU's interpolate crank position between pulses. CAS signals have more jitter and inaccuracy due to belt whip.
If you have an ECU that expects NA style cam and crank signals, his controller will output NA style signals derived from the NB signals. This should be more accurate than an actual CAS because he derives the signals from the crank, in a similar manner to how ECU's interpolate crank position between pulses. CAS signals have more jitter and inaccuracy due to belt whip.
#115
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Oh, absolutely. That would be a help.
Is that true, then, that your controller actually passes through the signals directly (or, buffered but without an interrupt) to the ECU, on non-CAS cars?
If so, I'd be very interested - if not, I might put something upstream of your box to sniff the signals and then share them with both. Any fixed signal delay won't hurt your box (up to maybe 500 ms. :-P - but a variable delay would hurt the ignition timing of a crank tooth wheel.
I'd really like to clarify this. And then buy one. :-)
Is that true, then, that your controller actually passes through the signals directly (or, buffered but without an interrupt) to the ECU, on non-CAS cars?
If so, I'd be very interested - if not, I might put something upstream of your box to sniff the signals and then share them with both. Any fixed signal delay won't hurt your box (up to maybe 500 ms. :-P - but a variable delay would hurt the ignition timing of a crank tooth wheel.
I'd really like to clarify this. And then buy one. :-)
#118
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
If you have an NB2 I expect that Kevin's circuit will simply share the crank and cam signals with the ECU. If you have an NB1 I think the factory ECU can accept the VVT cam signal as is. (the crank signals are the same)
If you have an ECU that expects NA style cam and crank signals, his controller will output NA style signals derived from the NB signals. This should be more accurate than an actual CAS because he derives the signals from the crank, in a similar manner to how ECU's interpolate crank position between pulses. CAS signals have more jitter and inaccuracy due to belt whip.
If you have an ECU that expects NA style cam and crank signals, his controller will output NA style signals derived from the NB signals. This should be more accurate than an actual CAS because he derives the signals from the crank, in a similar manner to how ECU's interpolate crank position between pulses. CAS signals have more jitter and inaccuracy due to belt whip.
Regarding the timing signals, this is correct. Through simple observation with a timing light on the crank pulley, the timing is significantly more stable than that of a car that is running from the OE CAS at a steady RPM.
Oh, absolutely. That would be a help.
Is that true, then, that your controller actually passes through the signals directly (or, buffered but without an interrupt) to the ECU, on non-CAS cars?
If so, I'd be very interested - if not, I might put something upstream of your box to sniff the signals and then share them with both. Any fixed signal delay won't hurt your box (up to maybe 500 ms. :-P - but a variable delay would hurt the ignition timing of a crank tooth wheel.
I'd really like to clarify this. And then buy one. :-)
Is that true, then, that your controller actually passes through the signals directly (or, buffered but without an interrupt) to the ECU, on non-CAS cars?
If so, I'd be very interested - if not, I might put something upstream of your box to sniff the signals and then share them with both. Any fixed signal delay won't hurt your box (up to maybe 500 ms. :-P - but a variable delay would hurt the ignition timing of a crank tooth wheel.
I'd really like to clarify this. And then buy one. :-)
Whether the user selects an NA CAS or NB timing output, the condition of the output is simply derived through a manipulation of the input within the interrupt routine.
![](https://www.miataturbo.net/images/smilies/smile.gif)