Hi folks
we're having some trouble related to a miata BP (non-vvt version) and need deeper understanding of ignition timing. AFAIK the ecu use the 1+2 pins on intake camshaft just for undestand if the engine is on a "even" stroke or "odd" stroke (i really could expain better).
The customer asked us to adapt a NA adjustable camshaft pulley with pins in order to get camshaft position signal (1+2 pins). We've alterady done it in the past with good results, however always with programmable ecus.

The issue is that as per pulley design, changing the timing with the pulley slider will result in changing the timing of the 1+2 pins. So che camshaft sensor could sense the pins +/- 16° crank degrees (the pulley on canshaft count for +/- 8° cam degrees).
Does anybody knows how large is the "window" for the original ecu to see the 1+2 pins? Will it pop CEL up because the pins is NOT when it is needed to be or it simply expect 1 or 2 pin in the whole 180 cam arc?

TL;DR : or has anybody make working the original NB timing 4 belt theeth off? if no error related to ignition/cam/crank showed up, the ecu did not check "where" the pins are related to crank, and they passing by is just enought.

 

Adjustable bracket
4 teeth is way off BTW

 

Maybe i explained not so well
I am talking about the 1+2 theeth of the CAM sensor
The car would still mechanically timed correctly, but as per the adjustable cam pulley is made, the theeth would happen to pass the sensor up to 8 degrees out of timing. Did anyone know of wide is the ECU window to see those theeth pass by before putting on a CEL or having issue?
On programmable ecu's like ME442 we tested it in the past: the ecu just want to see the theeth in the whole 180° arc, that's enought. But i really dont know about stock NB ecu

 

which i think is operatively the same thing as our adjustable trigger wheel ?

 

So is the question
"Has anybody run adjustable cam gears on an NB1 with a stock ECU"?

 

not really
maruha cam gear style has the notches on the belt side of pulley, so they stay in timing with the crank no matter how you adjust it
we have per customer request to modify a cam pulley for NA miata, and it has not the space for the notches. so they have to being placed on the cam side of the slider, so they account for the adjusting, and be adjusted w/ the cam (so out of timing in respect of the belt).

 

I am a bit confused, you have an NA8 or a BP? The NA8 uses the CAS, BP uses the cam/crank sensors. Are you wanting to put an NA8 adjustable pulley on a BP with a CAM sensor?

Edit: OK, just googled, I think I do understand now. Might be a silly question, but why not just get the Maruha pulley?

I do see that on some vendors sites they mention adding the timing nubs to the pulley, maybe contact them directly to see if they have any thoughts?

You could always test with a stock BP pulley and intentionally time it 1 tooth out to see if the ECU throws a code. I personally don't have much (any) experience with the stock ECUs. It is interesting that the Maruha cam elected to place the timing marks on the belt side of the pulley, this might be a clue.

 

unfortunately this would be the better way, but the car is not ours. We're a workshop near Maranello, specialized in na nb miata, and this customer ( NB 1.8 non-vvt) just bought the wrong pulley and is asking to us to try to modify it.

 

It only needs one pin. You can see its welded to a flat washer to place it on the scribe mark you made that represents the single node on the stock gear. This way you have a reference scribe mark if you need it . You will also need a spacer for the sensor. Gap for the node to the sensor I found needed less than business card. I also tried to match the shape of the node but that may not be necessary. I did this about five years ago on an AEM Infinity. The ecu may or may not matter.

 

On programmable ecu it's not really a matter
You can define them the way you want
The problem in the title is about the stock ecu, which definitely need 1+2 pattern, but i dont know if it can account for a slighlty varying in timing of them

 

Reread your first post about working with stock ecu. Apologies. Good luck. Update if you find a soultion.