I know the base timing is fixed on the NB. I didn't check timing with a light or go through the calibration routine. Should you do this with the NB?

 

yes

 

You don't set the timing, you tell the megasquirt where your timing is. You or your megasquirt have no idea what your spark advance is right now, and I'm sure you know that's no good.

 

Isnt the ignition map relative to the base timing? So even if the base timing was off, it would be offset by the values in the ignition table?

 

yes, but if your engine is at 15* and your ms thinks it's at 10* now you're running 5* more everywhere. or 10*. or whatever it is. or the other way around.

that is not good at all.

it takes all of 5 minutes to set it up though. and if its off too much, you can just adjust table accordingly

 

With my limited experience, it's more common that the outer ring of the damper slips than the fixed timing really being off.

So unless you really check the TDC mark, checking/changing the base timing can fool you.

It would be interesting to know how often a NB timing is more than 2-3 degrees off?

 

I think he's asking about the offset in MS, not actual physical timing.

On my '00 NB the offset had to be adjusted as much as 4*

 

I checked with the dyno tuner and he checked it. The offset is 4* according to his tune.

 

This^^^


https://www.miataturbo.net/megasquir...k-80800/page4/

Post #76 has some details about what happened to me and my base timing experience. Without it set properly, it gave me hell for the last 2 weeks trying to start. I thought I had base timing set properly according to my TDC marks, but in reality I was 10* off. So during cranking, with crank advance set to 10*, it was actually at 20* advance... Not fun. And everywhere else in the timing table, I was 10* more than what it said.

Luckily, I use 93 octane and I am not running any boost so I didn't melt anything or had any pinging/pre-ignition.

After sorting all of this out, the offset is 5*

 

Yes you have to do this (at least to check and keep your engine healthy) - but in reality we have seen timing offsets on NBs vary from 4-6°, most common value seems to be 5°.