OK i keep reading about megasquirt and i keep not finding a definate anwser about ignition. What do i need to control ignition on my 7. Its a s4TII. Can i use stock coils? The modified CAS? Trailing spark? Im lost and need direction. Thanks in advance.

 

Have you read the FAQ?

To control ignition you need:

1. Mod the board to add a 2nd VR input (assuming a V3) or build two VR circuits (assuming V2). Wire DB37 to circuit (I use spare pins).

2. Add pullup resistors to the three LEDs and wire them to the DB37 (I use IAC wires).

3. Set it up in Megatune.

That's basically it.

 

OK so I can order the MSII v3 and the pullup resistors. Are the parts to add the 2nd VR circuit in the MS kit?(Or seperate?) The second VR circuit takes care of trailing ignition The faq also states that you have to use the v1 chip to control the stock ignition. Is that still true? It also mentions a wheel decoder that cannot be configured for a rotary yet? I take it that the MS kit you assemble does not come with any type of wiring harness right? Thanks, l the info is confusing to me. I have read the faq and it confused me thats why I asked for clarification.

 

Don't worry the FAQ is just old.

I have had plenty of sucess with MS2extra1.0.2 code.

What you need to do.

Buy any complete MS2 kit from diyautotune or elsewhere.

Now these parts are extra and you will need to find them yourself.

4x 4.7k ohm resistors
1x LM1815N
1x 0.33uF tantalum capacitor
2x 10nF green capacitors
1x 18k resistor
1x 1M resistor
1x 1k resistor
1x 47k resistor
1x TIP122


OK

You need to do the 3 pullups on the LEDs, then you set them to FC trailing mode, and also enable rotary mode.

You need to build the 2nd vr circuit.

You need to change R4/R7 whichever is for the air temp sensor, to suit your FC intake air temp sensor.

You need to build the modified Fidle circuit to use the standard BAC valve.

Some hookup wire. And don't forget a quality tuning cable.

And people can help you with a tune to start off. I have some on my other PC.

 

OK.

You'll need to purchase these from an electronic store. Either somewhere local, or an online source like DigiKey. Parts list in post above.

No. The second VR circuit supplies the Megasquirt with the 2nd trigger from the CAS. The stock VR circuit on the V3 board reads the 24 tooth wheel, the 2nd VR circuit you build reads the two tooth wheel. The alternative is to not build the 2nd VR and simply chop two teeth out of the 24 tooth wheel. I don't like this approach as it means swapping/replacing a CAS is a real pain.

The FAQ is a bit out of date. Any of the MS-extra code will run rotary at this point. Either on the MSI or MSII.

Depends. DIYAutoTune (my favourite MS vendor) gives you a lot of choices. You can buy a kit, you can get it assembled, or you can buy just the board (don't do this!). I buy kits when I feel like putting 10 hours into assembly, and assembled when I'm lazy.

They also have some very nice wiring harnesses. These are flying lead harnesses so you will need to add your connectors as well as the extra wires for the CAS. I use the IAC wires to run the coils.

 

If you want to avoid the details of the VR circuit, see http://jbperf.com/dual_VR/index.html#Buy - Jean makes an awesome board that works very well and is designed to fit in the MS case itself much as the main board does. I'm just a satisfied customer of this guy, no personal or business connection. You still have to solder the components onto his PCB but the hard part for most people (reading and translating the schematic to real life) is done. $30 gets you the board and all components. He may even sell assembled boards, I don't recall.
-Mike

 

So if I cut out the 2 opposing CAS teeth then I dont need to worry about the 2nd vr circuit and I can still controll leading and trailing timing with no problems? Mycar is not running now and not any time soon due to everything I want to do. IS The 2nd VR circuit better than the 2 teeth being cut out? Advantages?

 

Yes, basically. But cutting two teeth from the CAS now means it's difficult to swap CAS's if the need arises.

This is the reason I consider second trigger "better" then modifying the CAS.

 

Cool I appreciate it everyone. Ill get back with more questions when i get the MS and start assembly and install. Ill keep yall posted.

 

also, cutting two teeth out of the CAS wheel is less reliable due to being more succeptable to noise. Its "harder" for the ECU to detect a missing tooth (and distinguish it from noise) than it is to detect the tooth from the 2nd VR wheel.

I built the 2nd VR circuit, attached the harness, and was able to get an RPM signal and run almost immediately because it was less prone to interferance. I had none of the RPM spike or noise issues that accompany the missing tooth method. These may be due to how the tooth was ground off, the code and detecting the absence of a tooth, or any other reason, but the 2nd VR circuit and stock CAS combination seem to be more robust.

 

Can you go into a little more detail on building the modified Fidle circuit, or direct me to a site that would help.

And Jobro, you said that you had some maps to start a tune with i was wondering if you could upload them.

Any suggestions to newb trying out megasquirt feel free to throw them at me

Any and all help is greatly appreciated!!!

Thank you,
Ian

 

DIYAutoTune has a writeup on how to set up the BAC circuit on their site. Go to the IAC Mod Kit page.

 

Got my kit today. Glens garage ms2 3.0 w/4bar map tuning cable and stim for $340 or close to it shipped yeah need 2nd vr circuit, pullup resistors, parts and time. Anyone looked on ebay I saw 2nd VR circuit boards for 25$ shipped i think it was. Any way im getting coming and I will ask questions as I make progress.

 

As far as the parts list post further up in this thread what resistors 1/4watt? 5% 3 watt 20% or does it matter, but im sure it does. DIYautotune has some mod kits with pullup resistors 470ohm 1/4 watt, and 1k 1/4 watt what % do I look for?

 

For the ignition LEDs, you need 4.7K 1/4W resistors. Tolerance is non-critical.

 

There are other reasons for sticking with the stock CAS setup as well..

The stock CAS setup is a little less noise prone, and the code for running it is more simple.

Ken

 

4x 4.7k ohm resistors
1x LM1815N
1x 0.33uF tantalum capacitor
2x 10nF green capacitors
1x 18k resistor
1x 1M resistor
1x 1k resistor
1x 47k resistor
1x TIP122
SO all of these resistors are 1/4 watt
Anything special about the other parts?
Thanks guys this is my first MS and 100% learning curve. Ill be back for more questions later

 

Well built the power circuit and no power on pin 31 to pin on the 40 pin tower? In step 22 im not using iac so do I ignore the step or follow the ignition jumper and what to? little confused

 

Ignore step 22.

If you get no power, start tracing backwards in the power supply circuit until you find power. If you have absolutely no 5V at all out of the regulator but have 12V before the regulator, the regulator is the issue.

 

SO pin 31 goes to the regulator that i installed on the heat sink? Think im following . Regulator was u5? Cool ill look for schematic to follow it back

 

The regulator has 9v 0v and 5v i have it hooked up to a 9v battery. Does this sound right?

 

OK, if you have 5V at F1?

 

Ok got it working. I missed l2 and c23 opps. Moving on mow ill keep updated. Thanks

 

OK well so far so good but i f*#@d up step 63 the cap 399-4329-nd with a 104 marking and broke the thing. I found a 104m at radio shack. Anyone know if it will work ? In fo on the bag is as follows
272-0135 radioshack number i think
0.uf
ceramic-disk capacitor
50WVDC max
high k dielectric
104M marking on the cap itself

Or could i use another cap in the ms kit i have a spare of?0.001uf 103?

 

104 is 0.1uF. The 50V rating is correct. You should be good to go.