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On my 2004 1.8 VVT MX5 engine I placed a 36-1 wheel thinking that would be better. Now it seems it is not, due to the cam teeth pattern not being available separately to choose in TunerStudio. So, I decided not to mess around anymore and change the trigger settings to Miata 99-05 as per the manual.

Last night (I froze my butt off in the workshop) I changed the 36-1 triggerwheel back to the stock MX5 one, with the four unevenly spaced teeth. I went into TS and:
Under 'Settings', "Trigger settings":
et trigger pattern to Miata 99-05
Set trigger angle to zero
Trigger filter to weak
I left trigger edges at 'Falling' as I never changed that in the first place from the base tune, so why start changing now.
Under 'Startup / Idle', 'Crank settings':
Fix cranking timing with trigger is on
The manual tells me to set 'Use new ignition mode' on, but I don't have that feature there.
I also set the VVT settings on, closed loop, and left everything else stock per the base tune. The VVT table hasn't changed, it is still called VVT Duty cycle.

The car started with the 36-1 wheel fairly decently, and I drove the car from the nearby carpark to the workshop (half a mile). Now with the changes made, the car doesn't start. I think it fires to early, backfires. I had a look at the trigger sensor and teeth.
At 10 degrees BTDC there is a tooth very close to but just before the sensor:

At TDC that tooth is certainly passed the sensor:
So that seems to be right in line with all I read about this trigger wheel.

This morning I went back into the workshop and did what previously helped with issues; I reflashed the firmware using SpeedyLoader and reloaded the current tune. Now the engine is completely dead, it cranks but no sign of life. The fuel pump does run.

TunerStudio shows me this error while cranking:
"Unable to read Logger data. Timeout of 2000 ms. exeeded". Googling gives doesn't give me anything I understand / can use. except for the complete phrase.

I made a composite log and that shows all teeth pulses nicely.

I'm in need of a little success here, please chime in if you know what's going on.


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It seems the error goes away when I restart the system. And only re-appears when I make a log. Maybe it is just that I crank more than two seconds. But still the car is dead. When I crank, the pulse width gauge, which I think gives me the current opening pulse width of the injectors, stays at zero. So, no fuel.

I keep searching, all input is welcome.

I had an intermittent no-start issue with *some* of the same symptoms when cranking: no rpm on dash or TS, the 'not cranking' indicator not turning green, not able to take a log (90 NA with NB2 swap).

Turned out to be the crank sensor to trigger wheel distance: somehow it had gotten too large (0.066" I think). Reset to 0.03" (I think!).

TL;DR: check crank sensor to trigger wheel spacing.
Thanks, I'll check that. I just got a reply on another forum that I could have put the 4 tooth wheel on backwards. I think I didn't, as I put it on the way the 36-1 was oriented, but I also realise the 36-1 in reverse will give the same result, the 4 tooth wheel in reverse will mess up the system.

[EDIT] Bummer, it was on correctly. I would have prefered a bruised ego and a fix... [/EDIT]


And then the VVT does not work, as it needs to be closed loop on the MX5. This is only supported with the standard trigger pattern. If there comes new firmware allowing proper closed loopt VVT control with the 36-1 crank and single tooth cam, I will do that. But as far as I am aware that is not the case, yet.

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