While watching/logging/adjusting. I am watching the gauges and the system never turns off the green sync light on the bottom, however the sync loss counter increases whenever a signal leaves the megasquirt or goes to the squirt (IE TPS change or fan on command. These are the only 2 signals that I see that have any effect on this.) The loss counter goes up. Both harnesses for the CAS are loomed seperately in the engine bay. Both are sheilded and grounded in the ecu wiring like in Aaron Cakes write up. The one off the extra board is a 4 pin wire, all additional wires are grounded at the squirt in the harness. Car runs fine, is it something I should be worried about?

 

What is the sync loss reason in your logs?

 

Theres an actual value for that? Guess I need to look deeper into my logs then.

 

Reason code 11. So, I wonder if I should loop all the 2 extra wires on themselves to complete ground circuits on the daughter board. Thats the one thing I didn't do. I left them open in the engine bay and tied them to ground at the ecu. Should be a good start at least.

 

So now its developing an occasional 17. Looped the excess wires back to ground. Guess I need to separate the signal wires from the ms to the cas all together from the rest of the harness.

 

Have the pots been turned fully counterclockwise?

Try tightening up the sensor gap in the CAS.

Generally speaking for shielding, as long as the CAS cable is fully shielded and grounded at the ECU end only, you should be fine. Assuming it isn't laying on the coils or anything.

 

Yes. They were turned multiple times. Since they changed to the clutch style you cant really hear them click. I turned them each about 15 times. I am in the process of double checking my grounds at the ecu.

As stated the only time I see the counter increase is on throttle or at idle when the fan command happens. Its faster on throttle input. It hardly climbs on fan input. The wiring doesnt lay on the coils. It runs along the main harness in a separate loom. The only time its not separate is where it comes out of the ecu and through the firewall.

Ive never heard of tightening the cass clearance. I guess I can look into that as well this evening.

 

Went checking for a spec for the air gap on the cass. Saw a spec up to 86 with the 12a. But nothing for the 13b.

I checked my wiring back at the ecu and all of it was done properly with maybe an inch of unshielded wire if that. The wiring for the expander board is double shielded with a foil wrap and a single strand ground

 

Watching the log again. Its not tps dependant its more rpm dependant. From roughly 1900rpm on, the lost sync count climbs rapidly. Airgap on the cas secondary is .007". However noted that the cas has play in it. Not sure if thats normal or not

Eidt : Never Mind lash in the gear mesh setup is the play.

 

Generally I gap them to the thickness of a business card.

ECU grounded to the battery or engine? Some setups are sensitive and must be grounded to the engine. Also make sure the engine to chassis grounds are in good shape.

 

Its currently grounded to the battery alone as per following your write up. Battery to engine ground is new. I will recheck the other engine grounds and change the gap on the secondary sensor tomorrow after work and report back.

 

Checked the engine ground at the firewall and addressed an issue there. Now loosing sync altogether at anuthing below 2500. Above that the counter climbs but isnt loosing signal. I will run one of the ecm grounds out to the engine on friday when I next get a chance to work on the car. For the record. Is sensor 2 off the expander board or off the main board?

 

I don't recall how the sensor is represented in TunerStudio but if you perform an ignition log you can identify which sensor wheel is connected to which sensor line.

Do you have another CAS you can try?

Can you post a summary of your setup again?

 

Ended not getting a chance to work on it this weekend as I had hoped. Family needed work done on one of there cars.

Setup is ms3x, turbo 2stock turbo. following your write up. My expander board wiring didnt have a shielded pair on it. I had a piece of 4 strand braided and foil shielded wire. I ran that for the expander boards pickup. Both shielded wires run along the harness inside the car. After the harness leaves the firewall, they are loomed in there own loom all the way up to the cass. They run along the main harness.

I unfortunately do not have access to another cass at this time. I will see if I cant catch it when it stumbles in the ignition log. Ive watched the pulses before but wasnt able to see it drop out anywhere and it appeared to have all its signals even with it setting the loss counters.

 

Did a composite log on the way home hoping to catch the drop out. I didn't catch a drop out, even though thats what it feels like from time to time. I did catch noise on the 2 teeth count input. If I remember right, that wiring was on the main board harness. I will have to verify it tomorrow. If thats the case, the main board harness wiring is right as it was a shielded setup from DIYAutotune. Not the wiring I had to add. I'll need to adjust the airgap on it and I assume run one of the ground posts from the fuse pannel on a wire to the keg somewhere to see if it clears this up.

 

i had someone ask me about Sync Loss counter at a meet this weekend... hes on the ms3pro but... i told em just to use the rx8 trigger, you'll be miles ahead, and it's going to get rid of so much old system the it will eliminate the problem..

 

Oh, forgot to suggest this...Try putting a high value resistor in parallel with each VR sensor. Start with 5K, then try 10K. Sometimes the sensors like a little load and the resistor can bleed off any little spikes that might be interpreted as triggers.

VR is such a silly system. It's a complicated signal to process because it ranges from millivolts to over 70V at full RPM in some cases. Then in the CAS they stick TWO bloody wheels on top of each other, with sensors close by, and expect no crosstalk!

Moving to a FD style trigger wheel (ie. Full Function) might be the ultimate solution w/a hall sensor.

 

I thought the resistor trick was applicable to high tooth count wheels which the 24/2 isn't. That's what Ken mentioned anyway

My experience based on an MS3 with MS3x running 13B turbo. Coil on plug sequential injection.

Does it get sync loss when cranking? IMO that is when noise from bad grounding is going to cause a problem because of the engine start current.
I bought a separate length of the shielded 2 core wire from DIYautotune for the 2 tooth wheel. I'd recommend that you do this. I don't quite understand how you have grounded these shielded CAS cable. This how I've done it: at the CAS, connect the two core wires to the CAS, leave the shield open at the CAS. At the ECU, connect both the shield and one of the cores to sensor ground, connect the other core to the relevant ECU input pin.

CAS VR1 (G+) - 24 tooth MS3 Pin 24
CAS VR1 (G-) MS3 Pin 1
CAS VR2 (Ne) - 2 tooth MS3X 32
CAS VR2 (G-) MS3X 12 (MS3X gnd)

Per an earlier question - the 24 tooth wheel is connected to the MS3 mainboard, the 2 tooth wheel is connected to the MS3X expander

In my install I have had two occasions where there has been a sync loss problem. 1st time was occurring in the mid range, similar to yours now. 2nd time was right at the top end. Both had different resolutions.
For the mid range problem, this was fixed by:
1) Installing a capacitor. Ignition noise was getting into the power system that was resolved by installing a 100V 100uF cap between coil power and ground. Diagnosed with an oscilloscope. Just a cheap uni-t hand held thing.
2) Adjusting both the pots on the ms3x. From the full counter clockwise position I put 1 clockwise turn on the trigger level pot, and one quarter a turn on the hysteresis pot.

For the top end problem a couple of years later I replaced the CAS. A small amount of gear backlash is normal btw. No idea what was wrong with the original CAS, clearance looked tight, same backlash as the new one.

Arran

 

The resistor depends. Sometimes the circuit just needs to be loaded down a little to attenuate the noise.

We're also getting to the point now where CASs are starting to fail. They are old. The magnets have been heat cycled, the connectors are crusty. Plus the Megasquirt circuit was never...the best...at handling it. The MS3-Pro / Microsquirt with it's Maxell VR conditioners is much better.

If I had some time, I'd make a run of Maxell VR conditioner boards for 'Squirt use. Too many projects on the go.

 

JBperf does this.

 

why tho, is it just me or is the solution just too easy not to jump right to the rx8 style pick up. i guess i forget not everyone can go out the shed and fab a bracket. but still the ones on the market are reasonable arent they?? 150 to 250?

 

That's probably the most ideal solution. But we really only hear about the problems that people have with the CAS, not the successes. Personally I've not had an issue with it in any of my installs, only helped those who have.

But I agree, for people having trouble, they should go to a better sensor arrangement if they can (not sure how power steering and AC interact with the various options, I know the Full Function requires modification with PS/AC). RX-8, FD, or aftermarket.

Just checked their website and found it. Awesome. Maybe once they are shipping again I will get my hands on one.

 

CAS VR1 (G+) - 24 tooth MS3 Pin 24
CAS VR1 (G-) MS3 Pin 1
CAS VR2 (Ne) - 2 tooth MS3X 32
CAS VR2 (G-) MS3X 12 (MS3X gnd)

Making me question my wiring. On first startup setting everything up with timing etc. I didny have to change my timing so in that respect I think the wiring is right.


The car ran great except for a sync loss counter on throttle input or fan output. Then it developed a drop out. Believing its all in the wiring I added looking back at the log that I took.

haven't had a chance to play with it any as family (and other projects. Big turbo 1.8t vw 20th anniversary car) have taken my time. Should be able to get back at it this weekend I hope.

 

So on a whim and thinking theres an issue with the 4 wire shield that I used I went and bought a microphone extension from radio shack that said it was shielded. Thinking I could solve this issue this weekend. Cut it open and low and behold one wire inside a plastic sheath and one wire for a braid for the shield. So much for that idea.

 

DIY might sell them for Jean. I know they sell some of his stuff.