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Old 05-02-2009, 10:07 AM   #1
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Default no rpm reading with Jimstim

I've nearly completed the build of my MS2E for a '00 with stock sensors.
All is working fine except that I can't get an rpm reading with the jimstim.
I'm using Abe's input circuits (on pin 24 and 25)

On the Jimstim, everything looks ok:
- dips are set for miata: 2,3,6 are on, others are off
- connected a jumper from 2nd trigger to pin 25 (IAC1A)
- primary tach jumper is in the bottom location, no other jumpers next to it

Basically like this:




On the MS I wired the 2nd trigger input to be fed from the IAC1A terminal (pin 25 of the DB37). I have continuity between Jimstim 2nd trigger pin and the input of Abe's circuit.

I can only assume this must be a software setting ?
I selected miata 99-00, falling edge, spark output going low, wasted spark, D14.
Anything else I need to set?
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Old 05-03-2009, 12:07 PM   #2
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When I select EDIS, I do get a reading so I assume that my primary input is ok (CKP) but that my 2nd input (CMP) must has a problem.

I still haven't figured out if I need to do the CMP and CKP input mods on diy as these instructions are for a 90-97. I'm using Abe's input circuits.

Anyone?

Last edited by WestfieldMX5; 05-03-2009 at 12:35 PM.
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Old 05-03-2009, 01:16 PM   #3
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Abe's circuit is a substitute for the DIY circuit. One or the other, not both.

It does sound like a hardware problem. Possibly something trivial like a pullup. Eyeball the circuit, dude. That's all we can tell you.
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Old 05-03-2009, 02:25 PM   #4
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I thought only dips 2 & 3 should be on. or is that 90-97 only.
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Old 05-03-2009, 02:30 PM   #5
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I checked the circuits and I really think they are ok. I measure the same values on every point of both inputs circuits.
I didn't build the diy circuits, just Abe's.
With dip 6 off, I get some rpm reading. I can set the rpm with the pot and I get a corresponding rpm value in megaview, but the reading constantly drops to zero and back. Doesn't seem right.
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Old 05-03-2009, 05:33 PM   #6
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Might wanna check the PROM rev on your JimStim. Switches 2,3,6 on is the correct setting for '99-'05 Miata, but this was only added in the latest (2.0 firmware.

Last edited by Joe Perez; 05-04-2009 at 09:17 AM. Reason: '99, not '90.
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Old 05-04-2009, 08:19 AM   #7
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I have 2 white dots, so this should be the correct firmware. Starting to think this is a JimStim problem, not a MS problem.
I'll try using the 2nd input circuit in edis mode, to make sure it's functional.
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Old 05-04-2009, 11:14 AM   #8
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Hi Frank,

Jimstim settings are just like mine - I also run Abe's circuit.
It should be working this way.

So maybe it really is a hardware problem...
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Old 05-04-2009, 04:24 PM   #9
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I found that the 2nd trigger output from the JimStim isn't working as it should.
Contacted Matt about this and apparently, some early JimStims had a problem with the Miata mode. I think I have one of them. Waiting for more info on this.

Edit:
Matt confirmed that the wheel pattern for the '99-up Miata was changed between the two-dot and three-dot versions of the JimStim. The two-dot processor had the wrong pattern. He's sending me an updated chip.

Last edited by WestfieldMX5; 05-08-2009 at 06:51 PM.
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