MegaSquirt 2 setup

Andrew7DG · 02-19-2008, 11:50 PM

I am hoping someone that has already done the Megasquirt 2 modifications will chime in.

I took the plunge and bought the Megasquirt 2 system (msII and V3.0) and have been assembling it.

Everything is working out and testing out great. It has been a wonderful winter project to keep me busy since I can't work on my car just yet.

however

I am having problems with the cas 2 trigger input

MS2-Extra Miata 4g63 Manual

I bought the 4n25 pin from DIYautotune and I bought the rest of the parts from radio shack.

after I assembled it, the ECU wasn't seeing the 2nd trigger input still

For a while I thought megatune version was wrong and msextra was wrong, also thought for a while that the JimStim wasn't outputting the correct signal

However after lots of testing I found out that the 4n25 pin wasn't sending the signal over like it should. I tested this using one of the LED lights on the JimStim and a jumper.

The 4n25 pin is seeing a signal on pin 1, 2 - a solid signal on 4 but no signal transfer onto 5 like it should be doing. (on the other 4n25 pin, 4 is solid and 5 is outputting the signal)

So now I am trying to figure out what in this setup I am doing wrong. This is kind of my first attempt at electronics and I am learning a lot but something isn't working at this stage...

So what can I look to that might be malfunctioning? Assembly? faulty 4n25 (but it is brand new so I don't really think that should be the problem)?
I am kind of looking toward the .01 uF Cap I bought from radio shack. it is kind of bulky compaired to C11 which has the same rating. I know the setup should work because there is another 4n25 pin setup built into the board that is reading the 4 slot sensor.

Does pin 3 or 6 on the 4n25 need to be hooked up to anything?

TurboTiger · 03-24-2008, 05:25 PM

Did you ever get this resolved?
I had a similar issue until I realized after looking at the pinouts closely, I had it wired to the wrong pins. I had assumed were numbered one way, when they were numbered the other way.

Andrew7DG · 04-08-2008, 11:20 PM

Yeah, My pin was bad I believe. I just jumpered and bypassed the 4n25. It reads RPM perfectly!

Now to get it installed into the car....

turboglenn · 04-09-2008, 12:09 AM

Glad you got it resolved. I tuned on a MS today for the first time in a few years and the newer stuff is really impressive IMO. I'm really lookking forward to getting one for our neon SOHC turbo 420a project. I"m not sure if i want the stress of building it as i'm more of a tuner than anything, i can wire complex electronics, but due to some spinal injuries from a motorcycle accident, myu hands aren't very steady anymore, so prolonged soldering periods really take a toll on me, but i'm too impatient to let it rest because my badgered body is acting up, so i'd probably end up with an accidental short in the board due to shaky hands with a nice soldering iron

Gotta say the newer MS firmware has really got me re-thinking the MSnS for future projects, it's good to see people willing to take on such a project and learn the ins and outs of EFI and some fairly complex electronics inthe common man's eye ( and mine too)!

TurboTiger · 04-09-2008, 12:26 AM

You probably shouldn't bypass the 4n25, as it provides some buffering from electrical noise which may cause a loss of sync. It will also protect the ms2 chip itself if you plug something else into it by accident. Just make sure you've got it wired to the correct pins according to the pin diagram here
http://www.ortodoxism.ro/datasheets/motorola/4N26.pdf

XtremeRS2gnt · 04-09-2008, 08:11 AM

You dont *have* to use the 425n opto isolator for the 2nd trigger input. It's only there for maximum input protection for the processor. If you know what you are doing, and dont wire it up to any high voltage, you really dont need to use it. All i used for my second trigger is a simple 5 volt pullup 480 ohm resistor, and it works just fine. You will not run the risk of lost wheel syncs using this method..BUT you MUST install and solder a .1 uf cap on the MS2 card itself, on the 2nd trigger input circuit. This cap basically goes right before the processor input pin, and R9 on the card. I was getting some lost wheel syncs before this mod, and after i did it, its perfect. You can even have this issue when using the opto on the 2nd trigger input, so keep that in mind if you ever get this odd stumble while steady state cruising. It will feel just like doing a data burn while driving. You get that short hiccup for a split second.

TurboTiger · 04-09-2008, 12:27 PM

Did you have to replace the .01uf cap as listed in the diagram here?
MS2-Extra Miata 4g63 Manual
Or did you add the .1uf cap in addition to the .01uf cap?

I'm curious since I haven't received a loss of wheel sync yet, and I've wired up the 2nd input according to the diagram above.

XtremeRS2gnt · 04-09-2008, 03:04 PM

Quote:

Originally Posted by TurboTiger

Did you have to replace the .01uf cap as listed in the diagram here?
MS2-Extra Miata 4g63 Manual
Or did you add the .1uf cap in addition to the .01uf cap?

I'm curious since I haven't received a loss of wheel sync yet, and I've wired up the 2nd input according to the diagram above.

No, this cap goes directly on the MS2 card itself. Check out this thread at the MS Extra forum where this fix came about: (im md95 on there BTW)

MSx/Extra EFI :: View topic - Strange problem..

I posted a pic of how i added the cap to the MS2 card a little ways down.

It's been 100% fine ever since i added the cap. I would say if you used the opto on the 2nd trigger input, you may not ever experience this issue..Even then, i only ever noticed this when doing steady state cruise on the highway for extended periods. It never happened at WOT, or even just driving around town. It was very strange. I just didn't see the need for the "added protection" of the opto isolator, which it's main function in design is to isolate potential high voltage kickbacks from a distributor coil setup. The CAS sensor is just a simple 0-5v signal, exactly what the MS2 chip runs off of. That, and i think i was the very first to test the MS2 Extra code for the 4g63, and i needed a quick way to wire it up to see if it worked.

At that first testing phase too, all i used for BOTH crank and cam inputs, were simple 5v pullup resistors, and no on board opto circuits. Worked fine.
Now i use the main "crank input" with the main on board opto circuit modded like "neon" input, and just a simple 480 ohm 5 volt pullup for the 2nd trigger input, and then for a low pass noise filter, that .1 uf cap on the MS2 card. Much easier and cheaper than using a second opto isolater, finding room to put it, ect.

TurboTiger · 04-09-2008, 05:26 PM

Aah, I see, you also had a v2.2 board, so it makes it a bit harder to add stuff without the prototype area.

Andrew7DG · 04-09-2008, 10:13 PM

Wow

I just looked at the pin diagram...

I may have wired it up wrong...

I also read that whole forum on strange problem... very interesting! However the picture is missing from that thread where you did the modification. You should post it up so I can see how you did the mod. I am kind of nervous about soddering anything onto the MSII but this would be very helpful if I ever experience the loss of sync (it may be already happening and I just don't see it because it isn't installed into the car yet.)

I am going to try to use the pin again and see if it still works. I still have the socket inplace and it won't be that hard to change it out.

Good info on this!!!!!

I wish I found that post a while ago when I was fustrated at this problem.

on a related note:

What I would like to do is make a tech thread of how to install MSII in the car. However I haven't completed the installation of the system into the car yet. I am still learning myself. Do you think it would be helpful to create a thread on here and post up how to installation outline and info? So many people (including myself) have questions about the system and if a how to article going over the complete installation was made, it would clear up lots of questions. If so I would need the help of all the experienced MSII people to help me along with this so I don't post any wrong info.

This is kind of a complex system for a newbie of electronics and I would like to make it as simple (educational as well) for people who are installing it into their car. Plus it would help me with the installation into the car.

TurboTiger · 04-10-2008, 02:06 AM

You need to be registerd on the msextra forum to see attachments, including images.

XtremeRS2gnt · 04-10-2008, 08:09 AM

Opps, yeah you have to be logged in to view the pics..

IF you use the second opto isolator, you prob wont need the cap on the MS2 Card. It would always be best to use the opto, just in case you do inadvertently connect that input to higher voltage, but if you know what you are doing, it shouldnt be a concern. IF all you use on the 2nd input is a simple 5v pullup resistor, then you WILL need the cap on the MS2 card. It's a delicate soldering process, as the holes in the MS2 PCB are small. Here is the pic of the cap mod:

I too was a bit confused on the pin outs of the opto isolator, but if you just sort of follow the main on board opto circuit, and trace the circuit, you can see what needs to connect to what pin on the opto(just reference the tiny dot on the opto).

Yeah, putting a nice install how to would be a good idea. It would be slightly different from 1G's to 2G's as far as some wiring goes, but it shouldn't be too hard to get something put out for installation. I was going to do this, but never got around to it... I mean, there really isn't going to be much of a how to i guess, mostly which wires need to be connected and their colors..

Andrew7DG · 04-10-2008, 08:31 AM

Well tried using the opto 4n25 wired correctly but it still wasn't reading input.

So onto plan B on the pull up resistor

Andrew7DG · 04-10-2008, 08:58 AM

This is kind of interesting about the board having a resistor on it.

I found two diagrams on how to wire up the input signal to the MS2

one found

MS2-Extra Miata 4g63 Manual

and the other found here

http://www.msextra.com/ms2extra/Igni...nputwitcc7.jpg

The difference is that one has a 1K resistor and the other one doesn't

I was trying to figure out why there was a difference between the two. Do you think the second one takes into account the 1K resistor on the board then?

XtremeRS2gnt · 04-10-2008, 10:39 AM

Quote:

Originally Posted by Andrew7DG

This is kind of interesting about the board having a resistor on it.

I found two diagrams on how to wire up the input signal to the MS2

one found

MS2-Extra Miata 4g63 Manual

and the other found here

http://www.msextra.com/ms2extra/Igni...nputwitcc7.jpg

The difference is that one has a 1K resistor and the other one doesn't

I was trying to figure out why there was a difference between the two. Do you think the second one takes into account the 1K resistor on the board then?

Yeah i dont know why those diagrams are like that..there is no need for that 1k resistor in the one diagram, as R9 on the MS2 card is a 1k resistor. If you decide to only use the simple 5v pullup instead, make SURE you mod the main tach input to what the 4/2 CAS mods are for tach input.. Then for 2nd trigger, add in that .1uf cap on the MS2 Card. If you look at the pic and your MS2 card, you will see R9 right in the corner there, and follow the tiny trace to the left of R9, and you will see a small hole at the end of the trace. This is where you put one leg of the cap. I had to use a small piece of a wire strand to fit in the hole, as the hole is too small for the cap lead to fit. Then i put the other end of the cap on the ground pin at the 6 pin jumper leads on the left side of the card. I want to say the ground pin is pin 2..I'd have to double check the schematics on that, or check mine out, but it looks like the bottom lefthand pin looking at the picture i posted. Also, i did insulate that cap and leads there after i took that picture..you dont want that shorting out on anything.

Andrew7DG · 04-10-2008, 11:50 AM

I did do the main tach mods for the main tach input. So that will run on the 4N25 that is on the board. The 2nd trigger will look almost (well exacly) like the one posted in your other post

http://www.diyautotune.com/images/fo.../fix_schem.gif

That should be the correct way of doing the 5v pullup from my understanding

Where the R 470 resistor has to be put in but the 1K resistor should be R9 from my understanding

Let me know if I have any of this wrong but i am pretty sure thats correct

Andrew7DG · 04-10-2008, 01:04 PM

well I have some good news and some bad news

Good news is that the 4-2 pull up works! Thanks XtremeRS2gnt

I cleaned up the proto area and there is a lot less stuff there then there was. I am just going to have to be extra careful when hooking it to the CAS. However like everyone else said is that the opto was there for added protection. But in theory there shouldn't be any power surge. For other people working on this system, I would try the 4n25 pin first but since it seems like there was a fault in mine, this solution will work for me. Plus I have extra room on my proto board for other stuff now. I also made sure that the wire from the cap to the MSII board was protected so no shorting out.

Bad news is that I was testing it out on the JimStim and for the fun of it I hooked up the spark to see what it was doing.

I am getting weird outputs on the D14 LED, D16 is doing fine but on lower RPM, D14 flashes almost drop to half the tempo (best way I can describe it) So it flashes once every time D16 flashes twice. But this is only on the lower RPM. I hope this didn't come from the modification, but everything is reading correctly, just output is kind of weird. Does anyone else have this happen? Am I just getting unlucky with this whole system?... I want to make sure everything is working properly before I install this system. Also I don't want to hurt the coil packs.

So one problem solved and another one to fix... Have to take a break first though

XtremeRS2gnt · 04-10-2008, 01:23 PM

How low of RPM are you talking? Is this in car testing, or are you just spinning a CAS by hand? If you are spinning the CAS by hand, you need to do it smoothly without any change in speed or sudden slow downs or stops. I'm not sure of the threshold for getting good rpm and spark, but i want to say it should be fine above 50 rpm. I would test more along the lines of cranking rpm, which should be anywhere from 170-250 rpm or so.

Does Megatune show consistant, steady rpm? Or do you notice it go to 0? Make sure you have the settings in Megatune set correctly too for all the ignition perameters. Oh i see you are using the jimstim..nevermind..

There were a few changes to the 4/2 cas code, and i'm not sure what the Jim stim is using..If you can use a normal 1G CAS and spin it with like a cordless drill, you can easily test it on the bench. Thats how i did all my testing. I just wired up a CAS to a 12 volt jump pack(to power the CAS), and just ran the 2 CAS signal wires to a "test" DB37 plug harness. Make sure to spin the cas's nub clockwise. I've never used the Jimstim, but i know you have to do some pullups on that as well, so be sure to follow the setup instructions properly and all jumpers are set right on it.

TurboTiger · 04-10-2008, 03:38 PM

I used the jimstim successfully on the bench for my setup. What does megatune say for rpm's? Are the rpm's consistent? Sometimes the led's don't light up fast enough or bright enough, so I wouldn't use it as anything more than a quick reference. At this point, you should be referencing everything via megatune.

Also, which firmware are you using?

Andrew7DG · 04-10-2008, 04:11 PM

Well I hooked up MegaTune to it to see where in the RPM it is doing this.

So far from what I could tell is it is around roughly 325rpm to 480rpm which isn't too bad because the car runs overs those RPM (exept maybe on startup for a little bit but still wondering whats going on...

It doesn't loose signal on megatune (RPM is not dropping to zero), everything is reading correctly.

*time passes*

Hooked the CAS up and spun the cas with the drill.

Does the same thing. But only in those RPM ranges and it only does it sometimes. I will probably be fine but still wondering what is causing that.

On top in megatune

MegaTune 2.25 p3 - MS2/Extra pre2.0 beta 2008015

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