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Old 07-18-2015, 01:13 PM   #1
t8fanning
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Default No RPM info with DSM CAS

I am having an issue with no RPM signal to microsquirt, so something is wrong with either my DSM CAS wiring, or something is wrong with my msq. The msq I am using for now is here: http://www.nsfabrication.com/megasqu...4_21.43.08.msq, but it is the same thing that propav8r posted in his writeup. The CAS settings came from gross polluter in this msq.

That makes me think it is the wiring of my CAS that is the problem. I wired it as a Mistubishi CAS with aftermarket disc as shown here:



I am using 4 LS2 coils in a wasted spark setup.

However, the recommended settings in the megamanual:



are different than those provided by gross polluter in his writeup. Did I wire my CAS incorrectly or should I use different settings in my msq?
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Old 07-18-2015, 01:57 PM   #2
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what do you get when you look at it with composite logging turned on?
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Old 07-18-2015, 02:24 PM   #3
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Does composite logging just mean data logging? If so, here's my datalog of one crank for a few seconds, a break, and another crank for a few seconds. Here's the link to the .msl file on dropbox: https://www.dropbox.com/s/3dlfxsp84i..._Test.msl?dl=0

Is there a better way to share files on here?

Additionally, I'm not sure my CAS is actually good. I plan to test it on an o-scope later today.
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Old 07-18-2015, 03:46 PM   #4
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no there's a specific logging setup for multiple trigger inputs
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Old 07-18-2015, 04:02 PM   #5
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Ah. I found it. Please excuse my ignorance, I'm a total noob at this.

I started the composite logger, started the car, and got an "Empty Read. No data Received from Controller".
Same message for each of the other loggers.
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Old 07-18-2015, 04:07 PM   #6
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General newb question on the microsquirt. Does it really use the negative side of the vr input? I've always used the positive side on my non micro installs
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Old 07-18-2015, 04:11 PM   #7
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Well I don't know if it really uses that, but that's what the manual led me to believe when hooking up a dual wheel, and that's how I wired it. But I guess it makes sense, because it also calls for a pull up resistor on each circuit.
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Old 07-18-2015, 04:17 PM   #8
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sounds like maybe it's turning off when you hit the starter
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Old 07-18-2015, 04:21 PM   #9
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Just searched it, V3 does not use the positive at all, but does allow for a 5v or 12v pullup. Maybe try the 12v
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Old 07-18-2015, 04:23 PM   #10
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Also don't beat up on the starter quite yet. Pull the cas and use a drill to spin it, make sure to spin it th correct direction
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Old 07-18-2015, 04:38 PM   #11
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I am planning on testing it with an o-scope and power supply today. I will hook up 12V to pin 3 and test signal between pins 1 and 2 to ground respectively. Is this method sound? I already tried to look for changes in resistance using my multimeter, but I think there is no change for this type of sensor.

I also need to check to see if it gets power during starting. It should, but I need to confirm.
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Old 07-18-2015, 05:12 PM   #12
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I don't have my notes handy, so I'll assume you have +12v and gnd connected to the cas correctly. To bench test it, you'll need to add separate pullups to the cam/crank outputs. You can pullup to +12v for testing (but should use pullups to +5 for real install). With the pullups, you should be able to spin by hand and see the cam/crank switch between ~0v and +12v (pullup voltage) with a multimeter.

If you have a scope available, and can spin well by hand or drill, the signals should look something like this (this was from a running engine, spun by hand will be more uneven):



If you have the paid version of MegaLogViewer, there's a "Render Including Non Interrupt Data" option when viewing a Composite Logger file that will make the displayed waves better match what you see with an oscilloscope.
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Old 07-18-2015, 06:11 PM   #13
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Just tested both crank and cam sensors with an oscilliscope. Here are the crank test results (please excuse the vertical video): https://www.youtube.com/watch?v=Okg2F4frPE8, and here are the cam test results: https://www.youtube.com/watch?v=dUeaSkBAmlU

The crank test looks great. I'm getting a nice square wave, but is the voltage ok? I'm getting about 5V peak to peak. The cam wave also looks as expected, but has a much smaller amplitude, on the order of mV. This might be attributed to the shoddy test setup, and I did see 5V peak to peak flash once or twice.
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Old 07-18-2015, 06:12 PM   #14
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Whos diagram is that? The outer teeth are the crank trigger and inner are the cam. That would mean on that diagram cam is on VR1 and crank is on VR2. That's opposite of common MS input logic.
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Old 07-18-2015, 06:12 PM   #15
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pullup resistor issue on cam if you're not getting a good wave consistently. without the pullups you get a minimal change on the scope (but it's there)
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Old 07-18-2015, 06:14 PM   #16
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Quote:
Originally Posted by gross polluter View Post
Whos diagram is that? The outer teeth are the crank trigger and inner are the cam. That would mean on that diagram cam is on VR1 and crank is on VR2. That's opposite of common MS input logic.
sure you're looking at the diagram right?

it appears to come straight out of the pdf documentation...

edit: you're right it is backwards. vr1 goes to the crank and vr2 is for cam.
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Old 07-18-2015, 06:15 PM   #17
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I got that diagram from the microsquirt manual v3.3. Maybe I'll replace both resistors.
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Old 07-18-2015, 06:25 PM   #18
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I wonder if it's an error in the documentation. Would it hurt anything if I switched them?

But even if they are switched I would still expect some signal in the composite logger.
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Old 07-18-2015, 06:30 PM   #19
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check your solder joint on the resistors and swap the inputs. won't hurt anything
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Old 07-18-2015, 08:03 PM   #20
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You need to adjust the "Trigger Level" on your scope. It should be a knob by itself. The current setting is shown in the lower-right corner of the display, as CH1 0.0v, with the little arrow also showing the level along the right side of the screen. The CH1 0.0v setting means to trigger the next scope trace when Channel1 Probe crosses 0.0volt (or auto trigger if signal crossing not found). Try adjusting it up to 2volts, or so, and you should have a nice steady display.

Your crank signal looked OK and I think the cam is OK too, but it was hard to tell without a proper trigger.
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Old 07-18-2015, 08:13 PM   #21
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I am away from my scope (it's at work) now, so I probably won't do anything further with it. I just wanted to verify I'm getting a signal, so I could cross that off the diagnostics list.

I replaced both resistors and swapped crank and cam wires to no change. Still no start, still no signal in the composite logger.
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Old 07-18-2015, 08:28 PM   #22
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Found the issue. I'm not getting any power to the CAS. I am going through my wiring from the stock K-jet relay now.
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Old 07-18-2015, 08:33 PM   #23
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The hi-res disc shown in the Microsquirt manual (6.9.15) has the crank signal on the inner sensor and the cam on the outer sensor. This is opposite of the Yoshifab hi-res disc. Use the swapped wiring, not the wiring in the manual.

With ignition on, and CAS removed but still wired, can you check that you have ~5volts (the pullup voltage) on crank & cam signals from the CAS? You may need to rotate it a bit if it happens to be over a hole. Also check that you have good +12v and ground levels at the CAS.

Update for crossing posts:
What K-Jet relay are you using? Fuel pump won't work.

As a safety measure, MS won't turn on the fuel pump until it detects good crank/cam signals during cranking. (It will run the pump briefly when you first turn on the ignition to pre-prime, but then shuts off until good cranking is detected.)
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Old 07-18-2015, 08:43 PM   #24
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Great. I swapped the crank and cam signal wires.

I am getting power for the megasquirt fuel pump relay from the K-jet fuel pump relay. I took 12V constant power to both my main and fuel megasquirt relays from pin 30 of the K-jet relay. I took ignition signal for both main and fuel megasquirt relays from pin 15 of the K-jet relay. And I put the output from the megasquirt fuel pump relay back to pin 87 of the K-jet fuel pump relay. I also took power for the CAS, ignition system, and both banks of fuel injectors from the megasquirt fuel pump relay. So it seems my problem is that megasquirt isn't getting a good crank signal, so it won't power the CAS, and since it won't power the CAS, it won't get a crank signal.

It seems I need to get power for my CAS, ignition system, and fuel injectors from somewhere else. Can I take it from my main megasquirt relay, or should I get it from somewhere else?
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Old 07-18-2015, 09:21 PM   #25
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Quick answer, without looking up kjet wiring, is:
- use main relay for CAS and for injectors (you may want a separate fuse for injectors)
- you can use fuel pump relay for ignition - no spark until cranking is detected is OK
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