Unable to get tach sync - MS3 - Jimstim
 

I am waiting for my stuff to arrive to build my jumper harness to go parallel with my stock ECU on a 2001.

I configured the MS3 thus: (only listing ignition related stuff)
Tachselect to VRIN
TSEL to VROUT
VRIN to 1K ohm to 5v in prototype area

R52 full counter clockwise
R56 clockwise 6 turns from fully CCW.

When I meter from pin 3 of U7 to R54, I get .03v, but from R54 to pin 2 of U7 I can get to about 3v if I bring r56 back a turn or two. Something about this doesn't make sense. I should be reading 3v or so to pin 3 of U7 according to everything I have read. Is the Pullup my problem?

What I am trying to do is get some indicated RPM so I can start testing my spark and fuel (LEDs on MS3x card).

When I do the jumper test on the JIMSTIM itself I get a flashing LED that tracks with the RPM C potentiometer - so I believe the JimStim is working properly.

Can you all help troubleshoot me and get me straightened out?

Thanks!

You'll get no RPM indication until you have both the cam and crank sensor connected.

When taking voltage measurements, always measure between one point in the system and ground, not between two points in the system. IOW, measure between R54 and GND, adjusting R56 to achieve ~ 2.5v.

Since you are running parallel, you probably don't need the pullup resistors on the inputs. The stock ECU is providing a pullup.

edit: You'll still need a pullup so long as you're on the stim, but you can set a pullup jumper on that.

Also, moving this to the MS forum.

Thank you sir, I meant to post it on the MS forum I just got sidetracked.

I set R56 (at R54 to ground) to 2.6V.

I re-installed the MS3x expansion board.

Set R11 on the expansion board (R17 to ground) to 2.3v where it topped out. Is this a problem? (I am so used to problems...)
Going off of some stuff on http://westfieldmx5.devocht.com/?page_id=995

Thanks again Joe.

What next?

2.3v is fine, this isn't a highly precise setting. The absolute minimum for capture is somewhere around 0.7 - 1v, to compensate for the forward drop across the output of the sensor. I like to set it in the midrange of the actual signal sweep (which is appx 1 - 5v) just to give it some headroom and noise immunity.



With both the crank and cam signals connected, the pots set, and the software configured for '99 Miata inputs and MS3X, you should be able to see an RPM indication.

Ok... we are getting somewhere.

JimstimX connected.
Jumper to 5V on Jimstimx.
Jumper from Secondary trigger to cam header on StimX.


I am getting some tach signal now, but its jumping from zero to whatever I set my pot at.

Very unstable. Its cool that my "spark" LEDs on the JimstimX are finally lighting though. That is a first for me.

Tooth Logger still doesn't seem to give me any useful data. What can I log that can help you guys in troubleshooting me?

Try a different mode on the Jimstim and in Tunerstudio.
I have a plain Jimstim, but I have never been able to get a tach signal on in 99-00 mode. Like you, I only get the flashing signal. When I set the Jimstim to CAS4/1 (and Tunerstudio as well), I do get an rpm reading.
When installing in the car, obviously I set it back to 99-00.
FWIW, $0.02, YMMV etc ;).

with frank's circuit, I get perfect sync with the jimstim in 99-00 and on the car.

Chiburbian, make use of the diagnostics tab and take some composite logs.

that's odd, ive never had the issue.

Input edge capture could be set backwards.

When I get home from work I will do a composite log and post. Thx all.

Here is a composite log at an unstable 2800rpm.

(this is with Miata 99-00 settings on ecu and jimstim)

Switched to CAS 4/1 for testing purposes on stim and ECU. Got stable RPM.

Do I just test everything with 4/1 then switch back to 99-00 when I plug it into my car?