Configuring Jimstim 1.5 for hall sensor (solved)

Building and using the Stimulator to test your Megasquirt

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sanger440
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Configuring Jimstim 1.5 for hall sensor (solved)

Post by 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.
Last edited by sanger440 on Fri Mar 30, 2012 6:44 pm, edited 1 time in total.
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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
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sanger440
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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.
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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
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Matt Cramer
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
sanger440
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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.
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Re: Configuring Jimstim 1.5 for hall sensor

Post by jsmcortina »

sanger440 wrote: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
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sanger440
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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:
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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
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sanger440
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Re: Configuring Jimstim 1.5 for hall sensor

Post by 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:

Image

Attached logs and files for latest settings.

Thanks for taking the time to help me here.

Charlie.
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sanger440
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Re: Configuring Jimstim 1.5 for hall sensor

Post by sanger440 »

Problem solved- I am an idiot. :yeah!:

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.
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