MicroSquirt.com read only forum (Jan.15,2018)

ok, please don't flame me for my stupid question...

I am running Alpha-n, and so far the idle is very nice (lumpy - wild cam)
I was reading that with Alpha-n you can not include engine load, so here comes Hybrid Alpha-n. I know where to set it up in the Megatune software.

But the VE table, how does it look like? What do I change, set it up?
How does the Hybrid Alpha-n works exactly?
I've read here on the forum something like you get Alpha-n up to 2000 rpm and then it switches to speed-density, is that right?

Thanks for your time everyone.

A good way to find out how it works is run your MS up on the stim, and look at how the tps and map affect the PW at different rpm, that way you'll end up knowing more about it than most of us put together : )

Ian.

Ian,

I have no stim here

I have no syringe at the moment, if I can get hold of one and some tubing I'll try to take a look, time permitting. From memory when I briefly tested hybrid a month or 2 ago it appeared that both tps and map affected the PW at all rpm, but don't take that as gospel, and I could have had it set up wrong.

Ian.

Yes, both TPS and MAP affect the pulse-width... the lookup in the table happens from TPS, but MAP is multiplied into the calculation. I'm not sure how well it works because the weighting that MAP should have is going to vary by engine and car.... but it probably does better than just plain alpha-n.

I just started trying to tune my motor in Alpha Numeric to try to get a better idle. (383 chevy with a fairly big roller cam) this has resulted in a radically different VE map than in speed density, the idle is better and the idle MAP is lower when in neutral or park but put it in gear and the tuning point goes into the upper left corner and gets very lean. I have pumped up the VE map in that corner (thus the strange looking VE map profile) After tuning the rest of the VE I enabled oxygen correction above 500 rpm and allowed 15% correction. This helped but am I doing the right thing here? And what is this speed density-alpha numeric hybrid, can you combine them?

cbx1147 wrote: ...the idle is better and the idle MAP is lower when in neutral or park but put it in gear and the tuning point goes into the upper left corner and gets very lean

Walter,

With speed-density the idle should be tuned for lowest possible MAP according to the manual. How can alpha-n make the MAP go lower, except maybe because the engine is running with a smoother idle?

With alpha-n I can't see how the tuning point can go into the upper left corner by putting the car in gear. If the throttle has not been touched then the tuning point will still be on the bottom row corresponding to idle tps position and rpm.

Hope this helps.
Ian.

Ian.

Ian,
Thanks for your reply. I probably was'nt very clear, the tuning point does'nt go all the way to the upper left corner but towards it. The VE table is laid out from 500 rpm to 7000 rpm and from 20 to 100 kpa. The motor never runs less than 40 kpa except during deceleration. Should I change the layout? Does it matter if decel goes off the table? The cam specs for this motor are intake .510/282 and exhaust .520/288 with a 720 cfm throttle body, MPI and 29 pph injectors.
Thanks,
Wayne

pardon my ignorance, but what all you call "stim" ? I don't know what it is, my english doesn't help much sometimes.

Thanks

diegom6 -

Stim is short for Stimulator - used for testing and diagnosing MS. See here: http://www.megamanual.com/v22manual/v1stim.htm
There are newer versions. Check with a supplier.

David