MSIII v3.57 No CAS or CAM
 

From what I can tell, I have no CAS or CAM signals. I have verified continuity on the wiring from the pins on the AMP connectors to the pins at the sensor connectors. I have verified 12v / ground at the sensor connectors. I have a fancier multimeter that is capable of measuring frequency / duty cycle, and have verified that the sensors are outputting something at the AMP connectors during cranking.

I have followed the instructions on setting the pull-up pots, and installed the resistor for the CAS pull-up.

This is a 2001+ VVT car.

If you followed the VR + pullup input, then input needs to be set to 'Falling Edge'.

Is the pull-up also installed on JP8 on the ms3x board? What size did you use on the mainboard?

The best thing to do here is post a composite log during cranking so we can see if the MS is seeing the inputs correctly.



SIDENOTE: This MS has the alternator control circuit built in?

I used a 470 ohm resistor. My logic (FWIW) is that the settings for the 99 from the DIYPNP would work with the sensor set. Hence the rising edge. J8 is jumpered.

Will get the composite log when I wake up a bit more.

needs to be falling edge.

Changed to falling edge. Added a picture of the composite log done after the change to falling edge.

looks like the crank and cam inputs are reversed. swap those wires.


should look like this:

https://www.miataturbo.net/attachmen...1&d=1317570810

I just checked and find this:

Pin 24, MS3 Main connector is connected to the CAS center pin.
Pin 32, MS3X connector is connected the CAM center pin.
This appears to be correct per the manual.
Should I reverse them?
Is it possible to reverse the signals in the tune?

(Posting from my phone.)

Your composite log suggests you need to swap them. You have no cas on your car.... you have a cmp and cmk signal.

Composite log is too short to be useful--can't see any patterns, or determine if there's signal there or just noise. Can you please capture a new log, cranking for 5 to 10 seconds?

That composite logger was cranking for 10-15 seconds.

I found that I wired 12v to the crank position sensor instead of 5v. I have corrected it, but that did not fix the problem. Does the cam position sensor get 12v or 5v?

I have tried to do another composite logger and get nothing on it. Like it is getting no signal at all.

I am going to change the crank position sensor pull-up resistor to a 1k. Is there a similar pull-up resistor required for the cam position sensor?

i used a 470ohm for my 5v pullup for the main crank input.

the ms3x has a built in pull-up to 5v through a 2.2K (JP7 jumper)

01 wiring diagram shows crank sensor powered from the main relay (12V).

The wiring diagram for the MS main connector has a note that a hall effect crank sensor needs a 5v supply. Now it looks like the cam sensor may also need 5v. Will rewire in a minute.

I reloaded the firmware and went to alpha 14 from 12.

why are you rewiring your sensors?

I had them wired to a 12v power supply, as per the stock wiring diagram. Do they get 12v or 5v?

They get 12v. Are we doing this on a 2001 car or just a 2001 motor? Redoing the engine harness? what's going on?

Because I honestly dunno why the wiring is being touched...

http://www.msextra.com/doc/ms3/hardware.html#wiring

In the main connector wiring diagram, between the pictorial representation of the crank sensor and the throttle position sensor, in small letters, "5v supply if hall sensor"

2001+ wiring harness

Ground up build. Smartwire solid state switching (no fuses or relays), stripped down harness.

The rest of the sensors come up, other electrical systems good. Just the CMP,CKP issue so we're assuming it's a software config issue and not hardware or wiring. Sensors are outputting a signal when checked on a multimeter. Have not checked on an oscope yet but I'm pretty sure we'll see normal wave patterns. Will also try swapping sensors but they were known good sensors to begin with so no reason for them to die suddenly, and at the same time.

Swapped them back to 12v

Since we have a running NB car waiting to be transformed, I pulled the sensor set out of it and installed it. Still no signals showing up in the composite logger.

We have a new MSIII coming tomorrow. Possibly an oscilloscope, too. Unless there is a problem in our tune settings, I am at a loss for what else to try.

If you are using the stock NB sensors they need to go to 12v not 5v.

Because race car.

You really can't test the sensors' output with a standard multimeter while cranking. You need a scope for that, and you can monitor conditioner input and conditioner output to make sure your VR pots are in the right ball park.

There is really only one useful test you can do with the multimeter to test for sensor functionality. Pull plugs, spin motor by hand. Probe the sensor output. You should see CKP switch between 0V and (appx) 5V 4 times per revolution. You should see CMP switch between 0V and (appx) 5V three times per every two revolutions.

To check soundness of your wiring, you can continuity check from CKP output pin to pin 24 on the MS main board. You can do the same check from CMP output to the pin you are using for cam input, JS10 or Expander 32 depending on how you did it.

Also since you were playing with trigger wheels, double check that you did not install the wheel backwards.

https://www.miataturbo.net/attachmen...ine=1317773390

We are still not running, with no change from yesterday.

We have been testing sensors, comparing between a running 99 with a DIYPNP and the MSIII 2001+

With the computers plugged in, probing the crank sensor wires with a multimeter, we see ~1.66 v at rest and ~1.77 v during cranking. This is consistent between the two cars. With the computers disconnected, I see .01 v static with ~.8v as the tooth passes the sensor. This is the same between the two cars. I then tested between pins 8 and 24 on the MSIII main harness, with the same results (.01 to .8v).

Anyone have any ideas about settings that I have not set right? Possibly a base map?

Please read post #21 and do the tests I describe. Testing with a multimeter while cranking is pretty much worthless. Testing with the ECU unplugged is pretty much worthless.

What are you doing with pin 8?

That exactly happens to me although is not the same car that I got. I resolve that working the r52 and r56 pots. Set both pots to zero and work with the r56 one turn clockwise at a time and check until you got a crank signal.

Your cam signal seems to look good.

After a call from Emilio (I didn't realize when I first saw this thread that it was his car) I drove up to 949's shop this evening, and after a long night (thanks for the beer and the burritos, by the way) it's all fixed and the engine is running.

The problem was that R56 on the main board and R11 on the MS3X board were set near the bottom of their range. These pots create the reference voltage which the op-amps compare the incoming signal to. With an open-collector sensor, the output voltage never quite drops all the way to zero, and the reference voltage was set just slightly below the "low" voltage from the sensors.

Apparently the documentation doesn't really talk about this, but it's fairly easy to adjust on the bench with nothing more than a voltmeter- no need for guesswork and blindly turning pots. For the main board, measure the voltage between R54 and pin 3 of U7 while turning R56. On the X board, measure between R17 and pin 3 of U7 while turning R11. In both cases, you want to see about 2.5 to 3 volts at that point, which puts you right in the middle of the actual output range of the sensors.


Incidentally, John, I was impressed by the job you did on the wiring. It all came out rather nicely.

One thing- where the wires (and the MAP sensor hose) penetrate the firewall, you really need to stick a grommet and/or some putty around there- those lines are all going to be cut to shreds on the track.

Thanks for the help Joe. Couldn't have sorted it quickly without you.
Grommet for that umbilical is on the list. All holes in the firewall need to be positively plugged to pass tech so it would need to be done anyway.

Yeah, John builds a damn nice car. :bigtu:

from msextra docs:

Hmm. Didn't see that when I searched.

Six turns on R56 might be about right, but two turns on R11 would be cutting it really close. I seem to recall having to crank that one quite a lot to get the reference into the 3 volt range. I'm sure it would run at a lower reference voltage, but why not set it optimally to give you the most safety margin?

just sayin'

I finally have had enough time off to come back and say thanks to Joe for coming down and bailing us out.

Had to do a few 20 hour days to get the car ready for a race last weekend, which really kept me offline for a while. Other than a few minor issues, the car ran well enough to complete about 6 hours worth of hard track time. We were pretty happy considering that it had absolutely no shakedown time before the races.

Thanks to everyone here who takes the time to help us "electronics challenged" folks out.

John

Glad to hear it- that was a pretty monumental task you guys accomplished. One of these days I want to see the car all buttoned up and rolling!

The cool thing about lofty goals is that sometimes you reach them.

https://www.miataturbo.net/attachmen...ine=1318437308

Joe Perez's nerddom never fails.

(Posting from my phone.)

Nice!

Beautiful!

I was really impressed by those LED lights in the shop- a lot brighter than I'd have expected. How's the actual pattern work out in the real world?

We had a working config a few races ago but decided to experiment with the low mount. Too low and aimed wrong for last weekends race. Have to mount the spot beams higher up and re-aim like we had them before.