Jump to content
HybridZ

No RPM indication with MS3 V3.0


seth1001

Recommended Posts

I've got my new MS3 hooked up to the standard stim...everything works fine but the RPM knob doesn't produce any indication in Tuner Studio. I'm fairly sure it's just my settings somewhere because everything else seems to work fine...but I've already set the ignition settings to "fuel only"...which is what I'm trying to set up for now. I don't have any idea what else I could do in the settings to make it work. Any suggestions?

Link to comment
Share on other sites

 

To get RPM with a standard Stim, you have to turn off the wheel decoder - user either Basic Trigger or Fuel Only for testing.

 

By the way, do you know if they're coming out with a megamanual for the MS3 any time soon? thanks.

 

Is this one close enough?

 

http://ms3efi.com/

Link to comment
Share on other sites

I've got a wire going from s12c to Js9...as per the instructions...I haven't set up any other jumpers or anything. I thought you didn't need anything else if you're just using the coil (-) as the trigger...but I'll check the ignition section and see if there's something else.

Link to comment
Share on other sites

Alright well it looks like I've got everything sorted out except for the diode. The instructions for using coil (-) tell you to put a 36v zener diode into D2 backwards..but the kit from diyautotune didn't come with an extra 36v zener. D2 is actually a GPP 50V or something...The D-extra...which is the closest extra diode provided is a 22V zener. Which one am I supposed to use?...Or do I have to go to the shack and pick up another one?

Link to comment
Share on other sites

The instructions from msefi.com are:

 

Note 3: Diode D2 is normally a 1N4001 installed to add an additional 0.7V forward series voltage drop (i.e. D1 + D2 + Vf_opto_diode = 0.7 + 0.7 + 1.2 = 2.6V). For Hall sensor use, install jumper in place of diode. To use in ignition coil primary flyback pulse detection trigger, replace with 24V Zener (connected in reverse, operate in avalanche mode), eliminate C30, and lower C12 value to 470 pF.

 

So it looks like they want a 24v zener. If DIY provides a 22v zener I would use it.

Link to comment
Share on other sites

I've done the jumper stuff but the directions I found read as follows:

 

V3.0 Opto-isolator (for coil negative fuel-only triggering):

a) Fit a 36V Zener Diode in reverse into position D2. Note, the Zener Diode must be fitted backwards, so the strip on the diode is the opposite end to the stripe on the main board! (This component is part of the kit from good suppliers)

 

 

You may be looking at the directions for MS2 V3.0...MS3 is different...here's the address where I found it:

 

http://www.msextra.com/doc/ms3/ignition.html#optov3

Link to comment
Share on other sites

I don't believe the instructions for this part should differ whether its MS2 or MS3. This is the same circuit on the mainboard in either case. It only controls the opto isolator input side. The opto output side interfaces with the MS2 or MS3 processor. I think either zener will work in either case.

Link to comment
Share on other sites

Well there's also some other stuff that's different too. I think whatever you put on the mainboard is going to affect the signals going to the megasquirt CPU...so I just went ahead and order some new zener diodes from digikey...it'll probably be another week before I can work on this but radioshack doesn't carry what I need and I can't get a response from diyautotune right now.

Link to comment
Share on other sites

Yes, use the 22v zener. I am not guessing about the post above when I said the main board is the same for either MS2 or MS3(for the opto circuit, maybe not for other circuits on the mainboard). I looked at the circuit and the zener diode has nothing to do with using an MS2 or MS3 processor.

Link to comment
Share on other sites

Well I finished all the work and I put the 22v diode in there but I still can't get any RPM indication. Also the left diode on the mainboard is staying on all the time now...it was doing that shortly before I finished setting up the board for coil (-), but not during initial testing of the board. To clarify...I finished the whole thing (or I thought I was finished)...then I hooked it up to the stim to check the inputs. Everything worked except for the RPM since I hadn't set up the board for that yet. After fiddling with some settings over a couple of days nothing really changed. Then one day that left diode lit up when I hooked up the sim and stayed on. I didn't think much of it...I just kept trying to get the rpm input to work. Now the board is all set up for coil (-) and tuner studio is set up for "fuel only"...but still no rpm indication and that left diode is stuck on. I can't find anything that will tell me what it means. Any idea what the problem is here?

Link to comment
Share on other sites

I assembled it myself...everything seemed fine during initial tests and that light seemed to come on randomly too....that is to say I don't think I changed any settings that would have caused it...but I don't know. None of the chips seem to be backwards either. Here's a link to a progressive series of pictures I took during the assembly. Maybe you can see if something looks messed up. http://www.mediafire.com/file/om7670o60u7brwd/MegaSquirt%203%20Build%20Pics.zip

 

Thanks.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...