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

Hi All

Hope someone can help with my understanding of the constants page.

If we consider a 4 stroke engine.

Am I correct in thinking the number of cylinders in the constants page is saying how many pulses the MS gets per 720deg of crankshaft rotation ?

So for a 4 cylinder engine set to 1 squirt and simultaneos staging, does MS fire in injectors every 4 pulses of the ignition input ?

What difference does the throttle body or Port make ?


Many thanks

Barry

As no body else has replied:-
You are correct with your engine cylinder/cycle understanding.
But don't think you can fudge the cylinder number to get the injections right as the number of cylinders also tells MS how many ignitions there are for a cycle and hence it claculates the RPM.
I haven't looked at the throttle/port parameters but pressume thats so it knows if you have throttle body injection or injectors for each port.

bazzer wrote: What difference does the throttle body or Port make ?

None at all - the code doesn't use it!

I'm assuming that a VERY early version of the code had planned on using it but that never got implemented and no-one noticed to remove it.

James

I'm assuming that a VERY early version of the code had planned on using it but that never got implemented and no-one noticed to remove it.

James,

Yes, I think that is right.

If I recall correctly (which is 'iffy' at the best of times) Eric never removed it partly because I think there may have been eventual plans for it (perhaps for things like 'auto-generating' warm-up enrichments, sort of like the VE table estimator), and also to maintain continuity (in case someone else with a custom code was using it).

But for the official code it has always been a 'placeholder' rather than a variable actually used in either MegaTune or MegaSquirt. Interestingly, with X-Tau accel enrichment on the way, it might be useful once again....

Lance.

Just below where the manual says to set the 'Port Type' under the title Before Starting Your Engine it implies that the TBI setting does do something.

From Manual

If you have a throttle body injection (TBI) system, verify that there is a small squirt of fuel (equal to the “prime pulse”) when MegaSquirt is powered up (by turning the ignition key to run), . . .