Yes plug and play, or at least as close to it as possible is the goal. This board however is just basically the next step in what i have been working on all along.
While i had originally played with the idea of building some extra Mini-MS boards into a plug and play solution for anyone who wanted them, the response i got was greater then I had expected. I had thought originally that the people most intrested in this would be the experimenters but the idea seemed to have a more widespread apeal, and while i would not have minded delivering what i was running in my own car to a small number of people for various i did not want to do it on a large scale. As there seemed to be a desire/need for a product of this sort though I set my sights on solving the problems i saw with delivering on a larger scale the greatest one being the complexity and time involved with the build followed closely by questions of durability specifically of the soldered connections to the main ECU connector.
The problem i see with adapting existing systems into a plug and play solution on a larger scale is all the custom work that needs to go into it. Every extra wire i have to cut and solder just adds that much more time. Having to figure out which wire jumpers which 2 pins really slows you down, especally when you have to do it 10-20 different times per build. I also saw every custom wire as a pontential source of failure and was not happy with that. This board is my solution to that, it takes the custom setup i have been running with and integrates it all into one board that solders directly to the d-jet ecu connector.
As for the details and your comments...
Yes, it does use the existing 914 FI harness, relay board, injectors and temp sensors. I have done away with the relays on the MS board itself and use all the stock ones. Controling the stock fuel pump relay is important because the stock AAR is also powerd by it.
Yes, the stock MPS and trigger points are eliminated but both may remain in place for appearance purposes. Also, i have been thinking about adding jumpers to the board to allow an easier way to take the MAP sensor off the main board and relocate it using the stock MPS wiring in case someone wants to be really sneaky and put it inside a gutted MPS.
2. My idea with fuel maps is to get as many as possible for common engine configurations, and possibly if this thing takes off, start a library of maps for common mods and cam setups. I have both a stock d-jet 2.0 and 1.7 here so those will definatly be first to be done. The 1.8 being a non d-jet motor complicates things a little bit as it was not a stock d-jet car so a decision needs to be made as to which intake parts to use when building the maps. Hopefully i will be able to build maps for a 1911 and some of Jakes setups as well. I spoke with him about Megasquirt a couple weeks ago and will probably be sending him some hardware when it is ready, so if we are lucky we may even get base maps that he tuned himself.
3. Yes, these wires are going to be left unused and can be removed however i do plan on adding extra jumpers in the ECU should anyone come up with their own uses for them such as relocating the MAP sensor or perhaps a custom triggering solution in the base of the dizzy. I would only recomend this with a new or rebuilt harness though due to the issues with the age of the harnesses that you mentioned. A custom harness could be very usefull in running these pins out to other locations in the engine bay as well. Depending on if you are going to run a TPS or not there are 11 wires from the ECU that are unused as well as 2 more unused locations where wires could be added, these could all be setup for custom purposes. So far the stock gorunds have proved to be addiquate however if you dont mind modifying the stock apearance there is always room for improvement. The only time so far i my system as failed was duing an autocross when i managed to lose my ground wires during a hard righthander. Funny that the only failure i have been able to produce so far is one that was a result of the stock systems design.
4. Very true - The 2.0 injectors are HUGE for the motor they came in. With an MS1 chip and standard code variants you will never get a good idle as the pulse width resolution is only .1ms. There are however hi-res code variants for the MS1 that give a resolution of .035ms at the cost of losing the pulse width modulation feature. This is a win-win as far as i am concerned as PWM seems to be where a lot of peoples problems with MS come from in the first place. The MS2 also has increased injector resolution as well increased resolution for everywhere else.
5. EMI - This is one area where i would like to get more testing done. I have yet to encounter it on any of the cars i have converted so i have not been able to personally investigate it. I did originally run a shielded wire for my tach signal but i have since removed the shielding and have still not encountered any problems. As of right now i am not sure if what people have seen is a result of the way they installed the system or possibly another varaible in their car, possibly a bad or nonstock alternator, regulator, coil or any number of things. Also i am not sure if what they saw was even EMI and not some other quirk. There was an older code version that had a bug that produced tach spikes that apeared to be very much like EMI. I encountered this during my first megasquirt install many years ago and tore my hair out trying to find the source of what i thought was EMI.
6.Resistors, yes these are needed in the circuit. These will be in the ECU but as to weither or not they will be on the actual board or mounted to the case is still in debate. For ease of installation i would like to be able to mount them on the board but it depends on how much heat the resistors i am using generate. I have not gotten that far in my testing yet and at this point just have them mounted to a heatsink plate in the case.
7. AAR is used, it is triggered by the stock fuel pump relay which is switched by the ECU. CSV is not used as i prefer to use the megasquirt cold start options and eliminate 2 more d-jet components. Again these can be left in place to appear stock if desired.
8. Yup! I like the way you think. This is why i am putting in jumper pads to the unused pins on the harness. I currently run closed loop on my own car however this is via an extra wire i run out of the ECU. With a custom harness all it would take is a single jumper wire in the ECU and you could have a very clean setup. I think having a custom harness that adds all the extra features like crank trigger and O2 sensor but still hooks into an ECU that apears stock would be really cool. Sort of a stock only better sort of look to it.
Lots of great ideas here and probably a lot more to come. My favorite thing about megasquirt is how it unlocks potential. No longer are we stuck with stock cams and displacement(perfect cheater system). No more injection system with zero feedback when troubleshooting issues. Tons of options.
This post is already insanely long but i will touch on a couple more points here that we have not mentioned yet.
TPS-I am setting up a location for an optional jumper or fixed resistor in order to elimanate the TPS. Stock TPS will not work and its really hard to get any aftermarket TPS to look stock. This will enable leaving the stock TPS in place for appearance but resorting to MAPDOT accell enrichment in the ECU.
Injectors- We will now be able to swap injectors to whatever we can make fit. 1.7 or 2.0 injectors could be run on either engine (1.7 prefered obviously due to the 2.0s being huge) OR even better, 1.8 injectors which have the better connector on them and are still available NEW! I think all the injectors used on flat 4 VW's are pretty much a direct fit physically so anything up through the late vanagons should probably work. Which brings be to another point... the late 2.1 vangons used a throttle body that looks as though it would be easily adapted to the 1.7 or 1.8 style intake, i mention it because of its 50mm stock bore. I am thinking a 2056 with 1.8 plenum and runners and 50mm throttle body might be fun to try. Not being limited by injectors or intake configuration we are free to mix and match as we like.
QUOTE(Jeff Bowlsby @ Sep 29 2010, 05:36 PM)
James...Wow...this is intriguing. I have not followed the whole thread, but what I surmise is that you are developing a MS ECU board, for fuel-only control, that could be mounted into the D-Jet ECU case?
This would utilize the existing 914 FI harness, relay board, fuel injectors TS1 and TS2?
You would eliminate the standard D-Jet MPS and trigger points?
If so, a couple of thoughts/observations you may have considered. Not critical, trying to help your progress, just to be sure:
1. Your efforts are commendable and if it all works out, this could be a windfall for 914 owners. Plug N Play would be the goal.
2. The offering could include standard 1.7, 1.8, 2.0L fuel maps for standard set-ups (reprogrammable of course for those so-inclined), so its a bolt on for most owners.
3. Reusing the existing FI harness would mean the MPS, trigger point branches could simply be cut off. The 3 ground branches would remain - 2 for the injectors and the third for the ECU/TPS ground...is this acceptable? Would a supplemental engine-chassis ground cable be advised? This assumes the FI harness is still viable and functioning after all these years which may be a stretch for some harnesses. New FI harnesses could be fabricated without uneeded circuits or with modifications as you specify.
4. Wasn't it true that for 2.0L injectors/systems, the MS does not have sufficient pulse width resolution, pulses were too rich - has MS changed or is this resolved? Dave Hunt burned up motors because of this and switched to SDS. Would injector changes or PWM be needed?
5. EMI has been a huge issue for several of the 914world members who have tried this conversion, these low volt PEFI systems are notorious for this...does the existing harness accommodate this or is internal shielding needed on certain circuits?
6. D-Jet injectors require power resistors...are these on the new board?
7. Your circuitry suggests that the existing AAR and CSV are used correct? Is the CSV turn-off after the starter quits, ECU controlled?
8. Maybe the four MPS wires, now not needed, could be preassigned on the new board to accommodate an O2 sensor for closed loop? A connector could be mounted to these wires and a supplemental harness run back to the O2 sensor. :thinking:
Rock-on