I'm going to be getting the Megasquirt running on our car this week, but I need to know: What is required for the car to create a properly timed spark? I've heard lots of different things, but nothing concrete!

 

I dunno what you're asking for...?
The stock CAS triggers at TDC (approximately) with the two "home" teeth, and then runs a "sync" signal with the bottom 24 teeth.
This is typically called a "multi-tooth wheel with home" set-up.
There are a few people running MS on their FC's - you might want to change your subject to include "MEGASQUIRT" to catch their attention.


-Ted

 

Well, I need to know what sensors are required for the computer to give a signal to the coils for spark.

I know the CAS, and I'm assuming the pressure sensor is still nessessary as the car retards timing based on the boost reading from that sensor. But what else? Water temp? Air temp?

 

I ran MS in piggyback mode with the stock ECU in my old FC, with MS controlling fuel, and the stock ECU controlling ignition. I had a spare stock ECU to hack, so here's what I did:

1.) Open stock ECU, cut conductors coming from O2, MAT, and CT sensors.
2.) Similarly cut conductors from primary and secondary injectors.
3.) Solder a resistor in place on the stock ECU's board to simulate warm operating temp (look up resistance at 180degF or so)
4.) Solder leads to each of the cut conductors, and run them through a hole in the side of the sto ECU body.
5.) Add a full-span TPS to the throttle body.
5.) Attach a DB37 to these leads, wire up a ground and switched power for MS, and connect the new TPS.
6.) Drop in a run/tune.

Using this method, the stock ECU sees a fixed coolant temp, sees a non-existant (or floating) O2, and MAT signal.

This was done to a stock FC, so the AFM remained in place. I did run briefly with the AFM disconnected, and noticed no difference in operation, but my testing was limited. It's possible a 'limp-home' mode would be triggered if running this way for an extended period of time. Depending on the complexity of the stock ECU, a simple fixed voltage AFM signal may be all that's needed to trick it.

This was done on my daily driver, and was driven for 18 months or more.

Roger.

 

The CAS is the primary engine triggering / position sensor.

You need to ask MEGASQUIRT about everything else, since I am not familiar with their systems.
It depends on what the MS does and what affects ignition timing.


-Ted

 

N1XXR,

I interpretted your second reply to mean that you want the stock ecu to control spark. If you are trying to run MS in full standalone mode, then you'll be one of the first to try out the new FC ignition support. It is not even close to plug-n-play at this point, so plan on spending some time sorting out the details. Follow the posts by muythaibxr in detail, as he's the guy that's been spearheading the FC/FD ignition control stuff recently.

Roger.

 

nope. its fixed and there is a plig and play circuit thats out now.

lemme find the particular post

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/fc-millenia-s-lysholm-supercharger-437282/

there it goes. read upo on the whole post. the whole post itself has tons and tons of info in itself.

 

Umm..I'm quite aware of the mods required. I took a look at that thread, and lo and behold...those are pics of _my_ signal conditioning circuit and prototype board from the msefi forum!

As it is now, the information is there, but plug-n-play it is not. You must build the stock MS, modify the board for spark output signals, fabricate your own twin LM1815 circuit for signal conditioning purposes, re-flash the box with upgraded 'rotary-capable' code, and then fabricate a harness or adapter to interface to your vehicle.

I suspect there is a market for someone to supply plug-n-play rotary-configured MS boxes. An enterprising individual could provide those mods listed in the previous paragragh, perhaps even with connectors to plug directly into the stock harness plugs. Then you've got a plug-n-play installation!

Roger.

 

For the purpose of getting the car running, Megasquirt will be doing fuel-only with the stock computer controlling spark...at least for a few weeks.

I have 10 LM1815N chips on the way, and I will be assembling that part once I get the car to the point where its running. I want to control the amount of problems I have when first setting up a Megasquirt.

As for the future...
The company I work for manufactures video arcade games, video poker games and pinball machines, as well as several other electronic devices. We also repair all the boards and make wiring harnesses for the whole setup. I have made a prototype harness for use in my RX7, but it is NOT for a stock (no BAC or anything like that, just air temp, water temp, rpm signal, injectors and O2 sensor...which is a wideband). As soon as I get it running, I will switch over to my other TII which is a stock setup, find a TPS to use and make an adaptor, make the harness, make the LM1815 circuit and manufacture a few for the consumer market.

 

I wish you luck.
I think the market is ripe for such a product.
There's a seller on eBay who is selling premade MS units for like $500.
I'm still skeptical if there is much savings over a Microtech / Haltech / Autronic, but if you can make money it, by all means go for it.


-Ted

 

Pfft, $500 is a ripoff. There are a couple places that sell them for $300 fully assembled and tested, plus another $50 for a harness.

 

Is this packaged for an RX-7?
I thought the kits were $300?
If the kits are $300, how can they offer it fully-assembled for the same price?

Can you offer the MS fully assembled with a harness for $350 and make money?


-Ted

 

i sell mine for much much lower.

i provide literally everything needed except the harness mainly because thats whack.

 

Ted,

The basic Megasquirt kit is being sold for $140. That is the complete ecu in kit form with case. Firmware upgrades, programming software, etc, are all free and open source.

A stimulator ($40) is helpful for bench testing, but it's a one-time purchase used by installers and hacks. The average end user wouldn't need one.

A relay board ($65) is nice in that it includes relays for fuel pump, injector power, etc. This functionality is already built-in to the average FC, so the relay board can be done without quite easily.

This prices are found here: http://www.msefi.com/viewtopic.php?t=4588

There are a few hardware mods required to interface with the stock CAS, and to drive the FC coil packs. These mods require a small prototype board and about $15 in parts.

So a bare minimum MS box with the required hardware mods is around $155 in kit form. It'll take about 4 to 6 hrs work per box to assemble, mod, and test for the first few. Later units might come in at half that time. The real time killer as I see it is on the support side of things. Anybody prepping boxes for a specific application like this should be expected to offer tech support for their product. The msefi forum is already inundated with support requests from folks that haven't a clue what they just purchased...

Roger.

 

Awsome, thanks Roger! Thats exactly what I was looking for!

I believe that will take care of my dilemma!