(Miata) Alternator control WOT feature needs some help

[stefanst]

Went to the drag strip for the first time yesterday with my '99 Miata.
Fun times
Looking at my logs I noticed that the alternator control WOT feature has a problem:
When I go TPS >90%, the voltage drops to the pre-programmed WOT-value (in this case 12.6V). It takes a little while to get there- around 900ms, but it gets there. Then, when I lift to shift, the target voltage returns immediately to 13.7V. It takes it more than 3s to get back up to 13.7V. While it's still trying to reach 13.7V, the TP is back to 100%, but the algorithm seems determined to make it all the way to 13.7V before going back to WOT mode. Now it goes back to WOT mode and while it's trying ta make it back down to 12.6V I'm shifting again.

The result of all this is almost the opposite of what I would like to achieve: With this algorithm we're charging the battery while WOT in 3rd, while not charging with the throttle closed.....

My preferred solution here would be to give the algorithm some wait period before going from WOT-mode to RUN-mode. I don't really need to have the battery charging for the 600ms or so it takes me between WOTs. So give me a second or two to shift before going back to run mode.

This little hiccup actually helped me realize that the voltage compensation on my injector dead-time is off, so something good came of it after all

[Matt Cramer]

...because if the Miata voltage is actually taking that long to hit its target, something's fishy.

[muythaibxr]

Agree, on every one I have seen, it tracks the target instantly.

[stefanst]

Sorry!

Here's the log. The time it takes to ramp up is apparently the programmed "ramp up" time. I didn't realize that it applies the "ramp up" every time the target voltage goes up.

And while at the strip I changed the alternator settings in order to see, what they influence, so my current MSQ is not 100% the same that generated the log. I may have slightly changed voltages- not sure.

[nathaninwa]

I'd be curious to see the et/mph difference between turning the alternator off to leaving it charging during a 1/4 mile run

[stefanst]

I'd be curious to see the et/mph difference between turning the alternator off to leaving it charging during a 1/4 mile run

With all the mistakes I'm making, I seriously doubt the alternator has any decisive impact.

But it IS much easier to complain about the car and it's parts than to improve yourself

[WestfieldMX5]

Just use one of these and be done with it.