Configuring Jimstim 1.5 for hall sensor (solved)

[sanger440]

I have a MS1 pcb 2.2 running ms1extra 029Y4. I have made the modifications to the PCB for ground switching ignition (wasted spark) I am in the process of getting all the settings for running wasted spark for 8 cylinders with a hall sensor using a 36-1 wheel. Everything seems to be working good on the Jimstim with my settings. I have leds blinking for ignition outputs A,B,C and with a jumper on the Jimstim, Output D. I put the MS1 together from a kit and set the ignition inputs together for MSns settings.

I have the Jimstim set to 36-1, inverted output on the dip swithches. I have the jumpers set for hall sensor (square wave) and 5v pull up (already set and assembled from DIYautotune.)

I have not made the modifications to the MS2.2 PCP yet to run a 12 v hall sensor (last mod I need to do).

The rpm pots work good, and my rpm readings in tunerstudio seem steady except for intermittently ( say every 20 seconds) I will get a little blip in rpm. RPM will drop a little and then go right back to being steady. I am thinking that this could be caused by :

1. I still haven't modified the PCP yet for a hall sensor input (haven't remove and jumpered D5 and D8 and did not install 12v pull up from D9)
2. Something else?

Thanks for any input.

Charlie.

[racingmini_mtl]

This small change in RPM could be due to having the coarse RPM pot just so that it is almost between two values. So once in a while it will read a slightly lower value and jump RPM by 256 RPM. You can just turn the pot a little and it should stabilize.

Jean

[sanger440]

Double checked all my settings and the rpm was still jumping maybe every 6-7 seconds approx 1,000 rpm. So I plugged in my old original stimulator with a 9v battery and rpm was totally stable. So I do not think it is just a case of the course rpm pot between two values.

I am assuming the old stimulator does not give the 36-1 signal properly, but the rpm was stable and the ignition LED' were flashing.

I will have to complete the PCB hall sensor modification and see if the jimstim 1.5 rpm stabilizes.

Charlie.

[racingmini_mtl]

For this to happen, there has to be a mismatch between the settings on the JimStim and on your MS. That is not a hardware or firmware issue.

The 36-1 pattern has been tested thoroughly on all the MS platforms and firmware versions and a 1000 RPM jump would have been discovered and solved years ago.

Jean

[Matt Cramer]

I've seen a jumping RPM before - both on Stims and on real engines - when one of the wheel decoder teeth was off by one position or two.

[sanger440]

For this to happen, there has to be a mismatch between the settings on the JimStim and on your MS. That is not a hardware or firmware issue.

I have no doubt that the Jimstim hardware and firmware are good.

I've seen a jumping RPM before - both on Stims and on real engines - when one of the wheel decoder teeth was off by one position or two.

Are you saying on of the settings in the wheel decoder screen is wrong? I will double check these tonight.

Thanks.

[jsmcortina]

Are you saying one of the settings in the wheel decoder screen is wrong? I will double check these tonight.
Thanks.

Yes.
Say if your intended trigger teeth were 1 and 19 but you'd entered 1 and 20 by mistake then it would throw the rpms and spark off by one tooth.

James

[sanger440]

So I have rewired my v2.2 PCB for a Hall sensor with 12v pullup. No change on the jumping rpm. I have double checked my wheel decoder settings and I think they as per the spreadsheet and other places I have seen in the manual.

If I put the Jimstim in Distributor/Edis mode, the rpm is stable, but if in 36-1 mode, rpm is unstable. The tooth logger in 36-1 seems correct to me. So it must be something wrong in my settings.

Attached are files from my setup:

[jsmcortina]

As a hunch, I think it is something to do with "trigger D return" being on the last tooth.
Try changing to "timebased" cranking and set the "return" triggers all to zero.

James

[sanger440]

Try changing to "timebased" cranking and set the "return" triggers all to zero

Made the changes as suggested, no change in the jumping rpm.

I did notice this time a spike in the tooth log , not sure if I saw that before, here is a picture:



Attached logs and files for latest settings.

Thanks for taking the time to help me here.

Charlie.

[sanger440]

Problem solved- I am an idiot.

Turns out I had the wheel stimulator setting enabled. should be spark>stim for wheel>wheel stimulator>off

Luckily I found a thread that outlined this little issue.

When I initially tried this, no rpm signal, so I enable it and got rpm but slightly unstable.

So I disabled it again, no rpm, turned the pots up a bit, perfectly stable rpm. Seems to work perfectly.

On to bench testing some coils. Thanx.

Charlie.