Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   MEGAsquirt (https://www.miataturbo.net/megasquirt-18/)
-   -   Tach signal with standalone MSI (https://www.miataturbo.net/megasquirt-18/tach-signal-standalone-msi-17138/)

paul 02-16-2008 09:23 PM

Tach signal with standalone MSI
 
Just installed an MSI standalone in my 94. Everything is running great but I get no reading on my dash tach. What needs to be done to send the rpm signal to the tach?

Joe Perez 02-16-2008 10:19 PM

I thought that in the '94 the tach signal came from the coils? Black/white wire that hits both coils in parallel, then feeds the ECU (2I), the tach (1H), and the diagnostic connector. Your coils have four pin connectors or three pin?

paul 02-16-2008 10:35 PM

they are 4 wire.

with my stock ecu in the car my tach works

with my pnp in the car my tach works

with my MSI installed parallel the tach works

with the MSI installed standalone, no tach

Braineack 02-16-2008 10:40 PM

ever see the pull up resistor on the 1.6L diagram for cops?

the tach signal needed a 1v power source. When standalone, you'd get no tach signal since you removed the ecu and it was providing that signal....maybe it's the same concept here?

paul 02-16-2008 10:43 PM

yeah did see that when building my COPs. has nobody done a standalone MSI on a 94-95 on this board?

Braineack 02-16-2008 10:52 PM

not that i can recall, other than the PNP guys.

reddroptop 02-16-2008 11:42 PM


Originally Posted by paul (Post 215472)
yeah did see that when building my COPs. has nobody done a standalone MSI on a 94-95 on this board?

I have.

You need to create a tach output circut. Takes up one of the outputs. I was researching a way to get around this, I had some leads, but I stopped when I pulled the MS out in september.

I can't recall if it is that the tach is either output straight from the ecu, or if there was a specific resistor that is on the ecu that makes the tach output work.

I don't think I saved anything besides some emails. I remember something about a resistor in the diagnostic terminal (10k ohms?) between 2 pins that was supposed to work, but it didn't work for my standalone.

I was and will be running a custom V2.2 pcb.

paul 02-16-2008 11:44 PM

well that info woulda come in handy before i bought it instead of another PNP. ~$200 in savings wasn't really worth it.

paul 02-16-2008 11:46 PM

I wonder if Jerry or Matt could help...

*cough*

reddroptop 02-17-2008 12:44 AM


Originally Posted by paul (Post 215503)
well that info woulda come in handy before i bought it instead of another PNP. ~$200 in savings wasn't really worth it.

I didn't say it couldn't be done. The MSPNP is basically the same thing as an MS1, just with all of the R&D done. Obviously they have a fix for it, I am betting they are using an output to drive this circut

http://www.msextra.com/manuals/MS_Ex...l.htm#tachoout

What I don't like about megasquirt personally, is that there are too few outputs to do everything. Then again my total investment is far less then even a V3 kit.

So I can't complain.

If I had the sort of money some people here have invested in their setups, I would go AEM EMS.

elesjuan 02-17-2008 05:41 AM


Originally Posted by paul (Post 215472)
yeah did see that when building my COPs. has nobody done a standalone MSI on a 94-95 on this board?

*raises hand*

1995.5 with no tach output from the coils factory.

http://megasquirt.sourceforge.net/extra/pix/tacho.jpg

Built that. Simple. Doesn't work yet because I've yet to have any time to locate the exact tach wire in the harness to send the signal to. Shouldn't be that big of a deal, just use a DVM.. One wire on the IG- position in on the Datalink connector under the hood, then one by one test the harness plugs until you find your wire.


Originally Posted by reddroptop (Post 215520)
I didn't say it couldn't be done. The MSPNP is basically the same thing as an MS1, just with all of the R&D done. Obviously they have a fix for it, I am betting they are using an output to drive this circut

http://www.msextra.com/manuals/MS_Ex...l.htm#tachoout

What I don't like about megasquirt personally, is that there are too few outputs to do everything. Then again my total investment is far less then even a V3 kit.

So I can't complain.

If I had the sort of money some people here have invested in their setups, I would go AEM EMS.

I disagree honestly. Including my extras I likely have less than $400.00 invested in the ENTIRE ECU project (including the laptop!) and are more than happy with the results... Plus I built it entirely myself.

Too few outputs?? What the hell are you trying to do? I've run out of things to control with it for the love of god!

http://megasquirt.sourceforge.net/ex...PCB_Pinout.JPG
That isn't enough for you???

shuiend 02-17-2008 10:21 AM

Wow this is great to see this thread. I am getting ready to go full standalone and not having a tach could be itneresting. Hopefully we figure something out soon.

Joe Perez 02-17-2008 10:37 AM

Paul, I just can't see why the coils wouldn't be providing this signal. Locate the black/white wire that used to go to pin 2I of the ECU. It isn't being grounded out, is it?

paul 02-17-2008 10:49 AM

Pin 2I is blank on the MS connector, just a bare pin, its not grounded out anywhere

paul 02-17-2008 11:01 AM

just to double check i swapped the stock ecu back in and tach is working.

Braineack 02-17-2008 11:35 AM


Originally Posted by Joe Perez (Post 215603)
Paul, I just can't see why the coils wouldn't be providing this signal. Locate the black/white wire that used to go to pin 2I of the ECU. It isn't being grounded out, is it?


I'm almost positive it's the same deal with the 1.6Ls and standalone. The b/w tach signal from the coils should have 1V provided to it, else the signal cant power the tach on the dash....

when you remove the ecu from the picture, we dont provide anything through 2I. The easiest way to do this may just be a resistor jumping power and the tach signal in the diagnostic connector box.

shuiend 02-17-2008 11:43 AM

So Scott When are we going to try on my car?

paul 02-17-2008 11:52 AM


Originally Posted by Braineack (Post 215620)
I'm almost positive it's the same deal with the 1.6Ls and standalone. The b/w tach signal from the coils should have 1V provided to it, else the signal cant power the tach on the dash....

when you remove the ecu from the picture, we dont provide anything through 2I. The easiest way to do this may just be a resistor jumping power and the tach signal in the diagnostic connector box.

1k? can i just jump it at the harness instead?

j_man 02-17-2008 01:07 PM


Originally Posted by Braineack (Post 215470)
ever see the pull up resistor on the 1.6L diagram for cops?

the tach signal needed a 1v power source. When standalone, you'd get no tach signal since you removed the ecu and it was providing that signal....maybe it's the same concept here?

Yes :) the '94-'95 is the exact same thing as the '90-'93. The stock ECU does the pull-up. Some wonder why didn't Mazda do the pull-up at the coil packs or at the tach, but IIRC the reason is - along with the pull-up the stock ECU has some primitive misfire detection and lights up the check engine light if it doesn't like the the square wave.

On a '94 with a standalone, if your current coils have the provision to ground a tach wire at every spark fire then all you need is the pull-up resistor. If one has changed the coils with ones without tach support, then he has to do the scheme elesjuan showed above

magnamx-5 02-17-2008 02:30 PM

I wonder if i will have an issue using my recently aquired millenia coils with built in ignitors and not being able to get a tach signal?

cjernigan 02-17-2008 03:02 PM


Originally Posted by magnamx-5 (Post 215668)
I wonder if i will have an issue using my recently aquired millenia coils with built in ignitors and not being able to get a tach signal?

You have the FSM diagram right? Post it up or something and we'll look at it. Maybe they have four pins (1 for tach) just like the miata and toyota coils.

magnamx-5 02-17-2008 05:27 PM

1 Attachment(s)
Attachment 214494
pic
manual from another forum
http://members.cox.net/sciberpunkt/images/cop-2.jpg

Joe Perez 02-17-2008 05:31 PM


Originally Posted by Braineack
I'm almost positive it's the same deal with the 1.6Ls and standalone. The b/w tach signal from the coils should have 1V provided to it, else the signal cant power the tach on the dash....


Originally Posted by j_man
Yes https://www.miataturbo.net/forum/../...lies/smile.gif the '94-'95 is the exact same thing as the '90-'93. The stock ECU does the pull-up.

It definitely ain't the same as the 1.6s if that's the case. The 1.6 igniter has a black/white wire coming out of it that feeds back to the ECU, however the tach signal is a yellow/blue wire which goes from the igniter to the tachometer and the diagnostic connector. On my car (MS, full standalone) I left the yellow/blue wire alone (still goes from igniter to tachometer) however my black/white wire is completely disconnected.

cjernigan 02-17-2008 05:48 PM

So this should work right guys?
http://i28.tinypic.com/fk4ole.png

Braineack 02-17-2008 05:57 PM

yeah or just try it in the diagnostic box, -IG to the 12v source +B

neogenesis2004 02-17-2008 05:59 PM

I haven't hooked up my tach for over a year, the rev limit in MS will stop me if I've gone too far....I can go by sound to give me a rough ball park anyways.

j_man 02-17-2008 06:43 PM


Originally Posted by Joe Perez (Post 215729)
It definitely ain't the same as the 1.6s if that's the case. The 1.6 igniter has a black/white wire coming out of it that feeds back to the ECU, however the tach signal is a yellow/blue wire which goes from the igniter to the tachometer and the diagnostic connector. On my car (MS, full standalone) I left the yellow/blue wire alone (still goes from igniter to tachometer) however my black/white wire is completely disconnected.

Then is the external ignitor of the NA6 doing the pullup and not the ECU?



j_man 02-17-2008 06:47 PM


Originally Posted by magnamx-5 (Post 215728)
pic
manual from another forum

IGF is your tach signal. You'll need a pull-up

paul 02-17-2008 07:02 PM


Originally Posted by cjernigan (Post 215737)
So this should work right guys?
http://i28.tinypic.com/fk4ole.png

add that pic to the archives for standalone MSI in a 94-95 cuz it fucking worked. Thank you Chad and Scott, no matter what OG says about you 2 you're OK in my book. :bowdown:


WOOT!

cjernigan 02-17-2008 07:17 PM

I'm just glad there are some smart guys on here that can figure this stuff out. Good job guys.

magnamx-5 02-17-2008 07:49 PM


Originally Posted by j_man (Post 215752)
IGF is your tach signal. You'll need a pull-up

hmm i guess i got more reading to do then. Chad what is a pull-up?

cjernigan 02-17-2008 07:55 PM


Originally Posted by magnamx-5 (Post 215769)
hmm i guess i got more reading to do then. Chad what is a pull-up?

The idea of a pullup resistor is that it weakly "pulls" the voltage of the wire it's connected to towards 5V (or whatever voltage represents a logic "high"). However, the resistor is intentionally weak (high-resistance) enough that, if something else strongly pulls the wire toward 0V, the wire will go to 0V. An example of something that would strongly pull a wire to 0V would be the transistor in an open-collector output.

paul 02-17-2008 08:21 PM

thanks for clearing that up

elesjuan 02-17-2008 11:03 PM


Originally Posted by paul (Post 215756)
add that pic to the archives for standalone MSI in a 94-95 cuz it fucking worked. Thank you Chad and Scott, no matter what OG says about you 2 you're OK in my book. :bowdown:


WOOT!

Son of a bitch.. :fawk:

Anyone happen to locate the pin on the 1995.5 tach wire on the boomslang? :mad: Position 2I has no wire on my cars ECU harness. I'm guessing but haven't had ANY time to check it out, but I'm guessing that its position 1F because my documentation shows its not used but I think theres actually a wire there.

grippgoat 02-18-2008 04:35 AM

You already fixed your problem, but I just want to feel important. :)

https://www.miataturbo.net/forum/showthread.php?t=9723

https://www.miataturbo.net/forum/showthread.php?t=10921

-Mike

paul 02-18-2008 08:00 AM

yeah, thats what Chad was reading when he told me what to do. he was referring to you here:


Originally Posted by cjernigan (Post 215759)
I'm just glad there are some smart guys on here that can figure this stuff out. Good job guys.


Braineack 02-18-2008 10:21 AM

wow i was right for once. now i feel cool. im glad i can regurgitate things out and sound all-knowing.

olderguy 02-20-2008 06:40 AM


Originally Posted by paul (Post 215756)
. Thank you Chad and Scott, no matter what OG says about you 2 you're OK in my book. :bowdown:


WOOT!

Where the fuck did that come from?

paul 02-20-2008 07:26 AM


Originally Posted by olderguy (Post 216992)
Where the fuck did that come from?

Have I been hanging around Louis too much?

sabretooth 02-20-2008 08:22 AM

For the benefit of other owners, I just BLK/WHI to 12v via a 1000ohm resistor, and I now have a working tacho. That saved me from having to duplicate the circuit I used to provide a working tach for my Haltech.

Zabac 02-20-2008 11:26 AM

im a little late here on the band wagon, but i do wanna let you guys know that all your hard work is appreciated and it will hopefully save many fools out there...starting with me...


All times are GMT -4. The time now is 07:06 AM.


© 2024 MH Sub I, LLC dba Internet Brands