VVT swap with Rev MS3, no start
 

Sounds familiar, right?

'93 chassis with MS3basic and VVT swap. Only thing interesting is the Tomei intake and exhaust cams plus SPM damper and proprietary 32-2 wheel. Wired per VVT megathread, and I've tested injectors A-B-C-D as 1-3-4-2. Coils A and B are firing the VVt coils. I'm getting cam and crank signal but lots of sync errors. Occasional sputters of life, but no matter what req fuel and/or throttle I throw at it it won't do anything but sputter. Let me know if you see anything wrong!

Post tune.

Here ya go

The crank sensor goes wonky a couple times, hows the spacing? Can you swap to a different crank sensor?

Cam signal looks gud.

Also, why is Cam input set to JS10, is that an MS3 basic thing?

.030

So the issue I see is the crank sensor is going low too many times. It looks like noise. But this causes the megasquirt to think that there are too many crank pulses. Which makes you lose sync.

https://www.miataturbo.net/attachmen...ine=1461199970

See how it goes low for a second there? It shouldn't. And thats why you get the loss of sync at the end, because it counts 35 pulses instead of 34.

So I say swap with a known working crank sensor, and a smaller gap.

https://www.miataturbo.net/attachmen...ine=1461200385

checking the gap again I noticed this tooth profile. Looks like a manufacturing mark from a burn table. Would this affect anything?

its the the tooth right to the right of the timing marks

Totally could. How many teeth from the gap is it?

I just counted your log. The miss is at the same place each time. its the 12th tooth from the gap. If that matches up with your count I'm 90% sure thats your problem.

If you close up the gap you might be able to get past it. But I would definitely be getting a new ring.

Yes that extra tooth machined on the wheel is the problem.

Dammit, that means pressing the pulley off while in the car. Booo.

Just did a log with 10 cranks, it's there on all 10, and yeah, in the same place. Lemme count where it is...Yup, once the 'bad' tooth passes the sensor, there's 11 good teeth and then the gap.

I would run a stock wheel, you won't have any problems with it, they are very reliable.

Its an aftermarket damper. You can't run a stock wheel with it.

You mean a stock pulley? The customer paid for the damper, I think he'll want it installed. I'll chat with emilio

No I meant a 4 tooth wheel that fits your damper. For sure use the damper you already got.

This was discussed recently. The 36-2 is just as reliable, and offers better timing resolution at high rpms.

Wrong. The OP in THIS THREAD is having problems with one of these parts you are defending to be reliable. How many OEM 4 tooth wheels have this problem? How many people have problems with their ecu decoding a stock wheel correctly?

An OEM wheel is incompatible with this damper. This problem could have occurred with a 4 tooth wheel just as easily. You are making a blanket statement that is just false.

Wrong.

We have run the proto 36-2 wheels for many hours under many adverse conditions on our dampers without issue. FM has many customers on their wheel for the ATI damper without issue. Superior to a 4T in every way. This one however, appears to have a manufacturing defect. Unrelated to the design configuration. A defect in an aftermarket 4T would have the same problem. We'll get it sorted out for Josh ASAP.