RB26 no RPM signal

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drew6
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Joined: Wed Mar 26, 2014 5:00 pm

RB26 no RPM signal

Post by drew6 »

MS3X on an RB26 using the stock CAS. CAS is wired as per instructions using 1k resistors from VREF. CAS has +12V on pin C and GND on pin D is good.

I'm getting no RPM signal what-so-ever. The tooth logger is showing nothing at all when cranking.

I'm running firmware 1.3.3 beta but have tried 1.3.2 without any success.
I have the ignition settings on RB25 and have tried changing the input capture and flip polarity without any success.
When I built the MS3 I had to TSEL to VRoutinv, however, I changed it to TSEL to VROUT but it didn't change anything.
I have adjusted the cam input potentiometers a full 5 turns clockwise without any change.

Any ideas? Where do I take this from here?
jsmcortina
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Re: RB26 no RPM signal

Post by jsmcortina »

It might be worth removing the CAS and spinning it with a drill. Measure the voltage the two signal wires and see if they are changing when spun at low speed.

As mentioned in another topic, I tested one of these CASes just a few days ago for a customer's MS3X.

James
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drew6
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Joined: Wed Mar 26, 2014 5:00 pm

Re: RB26 no RPM signal

Post by drew6 »

Hi James,

Thanks for the reply. On the low resolution wire I can clearly see the voltage go to ~5V to 0.xxV. On the high resolution wire the voltage goes from .1V to 1V when spun.

I tried turning up the cam input pots again but had no luck. I did however realize that the composite logger is now receiving a signal when I spun it on a drill. This may have happened after I switched to TSEL-VROUT. The tooth logger still sees nothing and there is no RPM signal.

Any ideas?

EDIT:

PROBLEM IS SOLVED. It appears one of the legs on one of my pull up resistor was cracked. Once that was remedied the engine showed strong and stable rpm signal and it fired up!
Vesku
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Posts: 38
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Location: Finland

Re: RB26 no RPM signal

Post by Vesku »

drew6 wrote:MS3X on an RB26 using the stock CAS. CAS is wired as per instructions using 1k resistors from VREF. CAS has +12V on pin C and GND on pin D is good.

I'm getting no RPM signal what-so-ever. The tooth logger is showing nothing at all when cranking.

I'm running firmware 1.3.3 beta but have tried 1.3.2 without any success.
I have the ignition settings on RB25 and have tried changing the input capture and flip polarity without any success.
When I built the MS3 I had to TSEL to VRoutinv, however, I changed it to TSEL to VROUT but it didn't change anything.
I have adjusted the cam input potentiometers a full 5 turns clockwise without any change.

Any ideas? Where do I take this from here?
Hi! Have been working with same problem few days and have no solution to this.
I´m running firmware 1.4 and have been tried 1.3.4 also without any success.
Same setup with CAS and have been spun it with drill with different speed but no signal.
When measured from low speed signal cable I have strong 4.93V-0.16V and same from high speed signal to msx. I don´t have scope.
TSEL is to VROUTINV, low speed signal to pin 24 to V3 board and high speed signal to PT4 pin 31 to ms3x board.
Just tried it with another ms3/ms3x board but still no signal.
I know that there must be some stupid mistake from me but I can´t see it... :oops:

My msq
Matt Cramer
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Re: RB26 no RPM signal

Post by Matt Cramer »

Please post a composite log as well.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Vesku
Helpful MS/Extra'er
Posts: 38
Joined: Thu May 20, 2004 8:54 pm
Location: Finland

Re: RB26 no RPM signal

Post by Vesku »

Here we go!

Edit. So I don´t have low speed signal?! At least it´s coming to V3 board connector. Need to study that...
Matt Cramer
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Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: RB26 no RPM signal

Post by Matt Cramer »

Looks like no low speed signal, all right. I'd check the VR trim pots.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Vesku
Helpful MS/Extra'er
Posts: 38
Joined: Thu May 20, 2004 8:54 pm
Location: Finland

Re: RB26 no RPM signal

Post by Vesku »

I tested them yesterday with different sets and no effect. Then I tested whole board with Jim Stim (36-1 signal, vr and square) so v3 board tach input should work. I have 1k input resistor in both tach inputs. Should I try 330ohm to low rpm input? Need to make more searching...
Matt Cramer
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Posts: 17499
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Re: RB26 no RPM signal

Post by Matt Cramer »

I'd check the CAS wiring.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Vesku
Helpful MS/Extra'er
Posts: 38
Joined: Thu May 20, 2004 8:54 pm
Location: Finland

Re: RB26 no RPM signal

Post by Vesku »

CAS wiring is tested from CAS to VR INput to V3 board. Fluke multimeter gave stable frequency signal there. With drill about 26Hz for low sig and nearly 1570Hz for high speed sig. Fast calculated my drill runs about 260rpm. :D For some reason signal don´t be seen on log. Is it safe to measure it from prosessor side? VROUT INV pin?

Edit: I also tested with 330ohm resistor for low speed sig but no effect.
Is someone running 1.3.4 or 1.4.0 code with Nissan CAS?
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