Making the original cluster Tacho work with Megasquirt

[Turbo_tracker]

Hello to all and thanks for creating this forum and fixkick info!!! its been a ton of help on my Geo tracker

Well my question is as follows:

I've owned a 91 yellow geo tracker since '05, kept it stock til last year when I went full on on modifying it with dual transfer cases (kicker3), 10" lift long arm suspension, 85 toyota axles and 33" mud tires after all that the little engine wasnt able to go at highway speeds (max 60 mph to the floor) so I decided a little radical mod and installed a K03 turbo on it, As I read it on different sites the stock ecu and fuel injection components werent up to the task so I had to buy and assemble a standalone ECU from Mega squirt (MS) and modified the engine intake manifold to be MPI instead of TBI (made a 2" adapter out of aluminum and machined ports on it to install 1 inj per cyl)

Ok, so now Im running the spark and fuel from the MS, the stock dash has the speedo, fuel gauge, charging lamp, high beam, 4wd and turn signals working also installed an AFR gauge, a mechanical oil pressure gauge, boost vacuum gauge and engine temp gauge, but the Tacho on the stock cluster is not working...

On the MS site it expalins 3 different ways to wire for the tacho signal: Does anyone can reccomend me wich way to try and wire the tacho?

here's a link to those instructions

http://www.msextra.com/doc/ms1extra/MS_E...m#tachoout

Also I removed all the stock wiring regarding engine sensors, ECU, radio, etc that were not needed anymore to make the new wiring look easier...

its been quite a mess for the last 13 months but at least its coming along

Here's a pic of my Tracker

Thanks for your time and help!!

[fixkick]

Hello to all and thanks for creating this forum and fixkick info!!! its been a ton of help on my Geo tracker

Well my question is as follows:

I've owned a 91 yellow geo tracker since '05, kept it stock til last year when I went full on on modifying it with dual transfer cases (kicker3), 10" lift long arm suspension, 85 toyota axles and 33" mud tires after all that the little engine wasnt able to go at highway speeds (max 60 mph to the floor) so I decided a little radical mod and installed a K03 turbo on it, As I read it on different sites the stock ecu and fuel injection components werent up to the task so I had to buy and assemble a standalone ECU from Mega squirt (MS) and modified the engine intake manifold to be MPI instead of TBI (made a 2" adapter out of aluminum and machined ports on it to install 1 inj per cyl)
Wow , and MPI 8v, cool. ! I did a 8v TBI with megasquirt.

Ok, so now Im running the spark and fuel from the MS, the stock dash has the speedo, fuel gauge, charging lamp, high beam, 4wd and turn signals working also installed an AFR gauge, a mechanical oil pressure gauge, boost vacuum gauge and engine temp gauge, but the Tacho on the stock cluster is not working...
it needs only and input from the minus side of the coil. but in your case, you have custom ignition right.
show me the schematic of you custom ignition,
on my web site i have the stock scope readings.
here.
http://www.fixkick.com/look/ECU-secrets/tacho.jpg
we can mimic that easy.
are you running CDI or MSD , it will blow the tacho up, if driven from 500vdc CDI systems, ask how to cur that.
if running MSD, they have and adaptor that allows that, on mine, the MSD has a tacho drive. (ask how to make it work with suz.)





On the MS site it explains 3 different ways to wire for the tacho signal: Does anyone can recommend me which way to try and wire the tacho?
there are like 10 ignitions systems you can run,
but, coil points, stock, MDS, CDI, or simple transistor drive (same as suz) or coil packs, cops, dual coil packs, , wasted spark, GM spare, ford, Chrysler. etc.

here's a link to those instructions

http://www.msextra.com/doc/ms1extra/MS_E...m#tachoout
the mS option that matches best is the coil option, they are just using any relay 12v only , to mimic a Induction primary to get the
50vdc EMF back kick as seen in my Jpg above.

Also I removed all the stock wiring regarding engine sensors, ECU, radio, etc that were not needed anymore to make the new wiring look easier...

its been quite a mess for the last 13 months but at least its coming along

Here's a pic of my Tracker

Thanks for your time and help!!

first off, thanks for sharing ! nice project, sounds like fun.

I have never reversed engineered the tacho.(i should have..) but It has 3 wires (gnd,12v and sig) and does trigger off the back EMF signal of the stock coil.
im not sure of the stock tacho is sensitive to duty cycle of the pulse. (many are) i suspect it is.

in a good tach its digital and only measures rep, rates but that is not common, in factory cheap tacho's.

what Ignition system are you running, that dictates solution.

cheers !

[gorkyb]

Turbo_tracker, just stopping by to complement your project. Love the rims, I was looking at these last night since mine are completely busted. American Racing polished aluminum right?

[Turbo_tracker]

first off, thanks for sharing ! nice project, sounds like fun.

I have never reversed engineered the tacho.(i should have..) but It has 3 wires (gnd,12v and sig) and does trigger off the back EMF signal of the stock coil.
im not sure of the stock tacho is sensitive to duty cycle of the pulse. (many are) i suspect it is.

in a good tach its digital and only measures rep, rates but that is not common, in factory cheap tacho's.

what Ignition system are you running, that dictates solution.

cheers !
[/quote]

Thanks fixkick!!!

Here's schematic that came with the Mega Squirt controller,

http://www.msextra.com/doc/general/ms1external.html

This is almost the way I have it wired, just need to solve some bugs than came out last night..

I didnt installed any custom ignition system: the MS has an option called "Distributor Based Single coil Setup (MSnS)" that gives you the option of using all of your stock components (at least in my case...)

So Im running the stock efi distributor, stock coil, stock tps, stock idle valve at TB, stock fuel pump...
(from that everything is mixed and matched: Evo afr gauge, custom fuel rail with a honda fuel pressure regulator, old junkyard 5.9 liter v8 dodge magnum injectors and some junkyard GM coolant and air temp sensors, etc)

Im using the hall sensor inside the distributor to generate the spark and is controlled by the MS board (it has the option of running a coil with a small internal mod still, I burned some components the first time for not wiring it right hehehe)

The MS board generates the signal for the stock coil to make the spark at the right moment...

Could it be that if I fit again the condenser and the noise filter back again my Tach would come back to life again? like the stock diagram attached?

And to your fist comment: yes it's been tons of fun just to be monkeying around to make solid axle swap, the dual t cases and now to make it perform, had learned a ton of stuff the good and bad way, But I would definetly do it again (now than I almost know how it would take me less time hahaha)

Anyways thanks a lot for the great info and support!!

---

Turbo_tracker, just stopping by to complement your project. Love the rims, I was looking at these last night since mine are completely busted. American Racing polished aluminum right?

Thanks and Yep!!!

Found 3 of them at a junkyard and bought the 4th at ebay... And yes the three out of the junkyard took a couple of hours of polishing to match the new one...

[fixkick]

that is correct.
if running the stock 91 dizzy and stock 91 coil and stock 91 ignitor module, via the MS, (like mine) do not forget to invert spark proper or the coil burns up. (one BIT data param., in software wrong and BOOM)
or the driver burns up or BOTH. scope the coil minus wire, before wiring in a real coil.

this is easy, just use any coil of wire on any relay. as a dummy load.
use and old VSV valve for an ignition coil. or a 100 ohm resistor, or the like. (think, enough resistance to flow current and not blow up parts)
test 1:
see that the spark COIL MINUS LUG ! stays at 12v key on, and only pulses low , when firing, if not? BOOM, lots of smoke.
running near infinite dwell is BOOM on MPI it's $400 burned up cops on a 2 +liter. a big FU.
Be glad you motor dont have 4 cops to burn up, and they are 10x more easy to do that.

Answer. wow , so easy , as , its stock spark.
then you left out 2 more stock parts.
the condenser. missing only causes radio noise. (auto systems , or ? other devices)
and the suppressor.<<< bingo.
the suppressor is the signal source from the coil.

if missing SUPRESSOR ,the brown wire dies, if it dies on a stock car , fueling is cut.
on a non stock ECU {MS-old}, (crash and burn feature skipped, and bad idea, I warned them but they , blew me off,,,,, never again MS for me.)
then the tach only dies , if the brown wire is dead. in your case.

put back the suppressor. I ran the stock harness too, using a very fancy adapter i designed. (so if MS blows up. the stock ECU just plugs in in 5min)
TBI all the way.

condensor not showning is simple drawing, below.
http://www.fixkick.com/ECU/8v-tbi-schematic91to95.jpg

[Turbo_tracker]

Sound very good to hear that, I'll be doing those connections later today to have a working instrument cluster again!!!

By any means Fixkick do you have pictures of the condenser and the noise supressor?


Thanks!!

[fixkick]

Sound very good to hear that, I'll be doing those connections later today to have a working instrument cluster again!!!

By any means Fixkick do you have pictures of the condenser and the noise supressor?


Thanks!!

a blob, with NS on side.

i have suz, pn. if need be

the tacho needs this. or the brown tach wire will be dead city.

[Turbo_tracker]

Great picture!!!

Thanks

[Turbo_tracker]

Well, got it wired back again last night and the temp gauge also: so now I have a fully functional dashboard again

Only one problem: the Ms box "reseted" randomly about 6 times last night while ajusting idle and hot start parameters, but ran great otherwise accelerating and everything, but today in the morning it started ok, but got extremely rich after 5 minutes of driving and when I shut it off I wasnt able to start it back again ( raw fuel was coming out of the turbo downpipe, as im not using an exhaust yet)

Could it be the Noise supressor is affecting the MS? and wiring back the condenser could help cure that failure?

I know this is not an MS forum, But you have lots of knowledge and wanted to take a chance asking you that...

Thanks Fixkick!!!

[Turbo_tracker]

Well just got the chance to go back for the car and tow it to work to dive further in the problem, and just found out then CLT plug was off the sensor, just pluged it back and the car fired right up...

Well false alarm, and Im just begining to learn the new tricks this now modified tracker has stored for me,

I guess it will be more fun that just wrenching in it all the time: and by the way, Im just at 5 psi boost now, and my intentions are to go up to 10 psi boost!!!

The turbo made a huge diference in driving, as now I can rip the rear end loose very easy from standing still and cruise at the highway at 75 mph without breaking a sweat

definetly better than going with a larger engine, from my point of view...

Let me get some more seat time and will upload some vids to youtube and post the links.

And then again: Thanks for all the amazing information shared here!!!

TT