Synch vs Asynch fueling

[EagleMark]

What about engine rotation? Time intake valve is open? As RPM increase this time decreases. BPC time is directly tied to this available time.

I'm not saying your wrong or I'm right, just can't make sense of it. I know for a hands on fact Asyn is horrible idle and low RPM tune, but it is firing both injectors so more fuel for higher RPM.

That said I'm trying to get my Sync bin to go Asyn at WOT above 3500 RPM where it goes 100% Duty Cycle. Just haven't figured out the settings yet. My setttings are in that other thread and clearly shows it should be going Async... but does not... EBL does it. But seems they have some issues in the transition. I'd like to figure out the math for all the BPW/BPC Sync to Async etc... settings instead of guessing. Already found the Cop Car injectors don't put out more fuel! They have a lower BPW/BPC so they don't go 100%/Static at 3500-3800 RPM... yes more LB/HR but the lower BPC makes them the same each firing as regular 5.7L injectors.

[RobertISaar]

synch vs asynch =

synchronized to DRP vs not synchrnoized to DRP.

converting the BPW into a duty cycle(instead of a timed burst) is a dead giveaway of asynch. consider this: with synch, the injector pulses happen when the reference pulses happen, maybe a short delay, but they're directly driven by it. with asynch, ref pulses are needed ONLY for the speed-density calc, it doesn't care when they happen, only that they happen. converting to a DC takes away the timing and just flows the calculated fuel while running at whatever speed loop(was it 80Hz?). it CAN work, but there's no real reason for it to be used when you have the capability to run synch.

[EagleMark]

Thanks Robert.

it CAN work, but there's no real reason for it to be used when you have the capability to run synch.

I wonder what GM was thinking when they did this? V6 bins are all Async, harldy any V8. Do you have any idea how much space Async code takes up? Sync takes a few lines, Async seems to go on forever...

[RobertISaar]

async as a main fueling scheme is pointless... using it when necessary for AE fueling, valid use.

if you want large and pointless, the idle gain table in the MPFI 60V6 masks fits that description. 112 value 2D table used in the O2 sensor logic to change the rate of closed loop correction. then there's the semi alpha-n fueling mode that's absolutely hell to tune correctly.... more examples of GM doing stupid things in the code? SFI 60V6, the low BPW injector offset table is 255 bytes of 2D insanity....

it really doesn't surprise me at all to see these kinds of things.

[EagleMark]

async as a main fueling scheme is pointless... using it when necessary for AE fueling, valid use.

So all that Async code is for AE?

[RobertISaar]

probably not. some of it is bound to be for AE purposes, but from the way it sounds, a pretty big portion is being used for async main fueling.

[damanx]

This might be a dumb question, but has anyone actually run a scope on the injectors while driving?

[EagleMark]

Not that I know of? Be a weird wiring job to get scope hooked up...

There's an Async flag in the $42 data stream, it comes on during Decel or DFCO so you can tell when Async occurs.

I've been reading the disassembly half the day and only time Async/Sync parameters come up is during DFCO/Decel.

I think theres something completely different in V6 bins to make them run Async?

[damanx]

Not that I know of? Be a weird wiring job to get scope hooked up...

There's an Async flag in the $42 data stream, it comes on during Decel or DFCO so you can tell when Async occurs.

I've been reading the disassembly half the day and only time Async/Sync parameters come up is during DFCO/Decel.

I think theres something completely different in V6 bins to make them run Async?

As far as hooking up a scope, just two probes to the injector outputs from the ecm. That is how I did it in that video. Could run a third probe for a trigger off the Reference pin at the ecm.

You could tell then when it's firing either way.

[EagleMark]

Added quote from other thread.

Synch BIN files WILL NOT run a 60° V6.......They require an Asynch on BIN. Due to the firing order and intake pairing you will have two very lean cylinders with a synch bin.

[ony]

that syn bin worked pretty good on a 4.3, but there intake manifold is kind of a plentum chamber, I lost some mpg with the syn vs ays bin but it run good a little rich, run out of gas money so I quit running it, bin following some threads and I think that I should have changed the bpw constants alittle the rotation firing order I don't know about. them 60 v6s need a plentum manifold ,they would run better with a stock bin.

[RobertISaar]

.... how is it 60V6 specific?

60V6 firing order is 1-2-3-4-5-6, 1/3/5 being one bank, 2/4/6 being the other. with 2 injectors(one feeding each bank) and firing alternately, i don't see why it would be an issue running synchronous pulses? http://i.imgur.com/AXd9JIu.png due to the way the TB is offset, i'm trying to see if the injectors aren't setup to feed bank specific, which would certainly cause some odd things.

a 4.3 is 1-6-5-4-3-2, 1/3/5 being one bank, 2/4/6 being the other. in other words, setup the same, just different cylinder numbering. http://i.imgur.com/gOgLQQs.png

i don't see why either one would need asynchronous fueling to fix a fuel distribution issue, let alone one needing it and the other not needing it. i need better pics than what i'm finding, factory documentation is worthless for this as well.

[Fast355]

.... how is it 60V6 specific?

60V6 firing order is 1-2-3-4-5-6, 1/3/5 being one bank, 2/4/6 being the other. with 2 injectors(one feeding each bank) and firing alternately, i don't see why it would be an issue running synchronous pulses? http://i.imgur.com/AXd9JIu.png due to the way the TB is offset, i'm trying to see if the injectors aren't setup to feed bank specific, which would certainly cause some odd things.

a 4.3 is 1-6-5-4-3-2, 1/3/5 being one bank, 2/4/6 being the other. in other words, setup the same, just different cylinder numbering. http://i.imgur.com/gOgLQQs.png

i don't see why either one would need asynchronous fueling to fix a fuel distribution issue, let alone one needing it and the other not needing it. i need better pics than what i'm finding, factory documentation is worthless for this as well.

I had the same thinking as you when I first started tuning one. The air/fuel ratio variations were fairly extreme, 2 plugs would be powder white and two black as charcoal. Switched back to a 4.3 Asynch based .bin and my trouble went away. I had a crane 272 cammed 3.1 under the stock 2.8 TBI intake, bored to use a 4.3 TBI. Was running the 7427 PCM and a 95 F-body 4L60E behind it.

[RobertISaar]

is the 2.8/3.1 TBI intake just that bad in terms of fuel(but not air) flow distribution?

i'm having a hard time visualising how injecting based only on a duty cycle would prevent it, but firing when reference pulses happen would cause it... the same amount of fuel would be injected in theory but the timing of the fuel injected apparently is that critical to equal distribution?

[ony]

Robert I got confused about intake manofolds the 60v6s I worked on was port injection my 4.3 is a thb lot of differents looking into the way the manifold is made sorry I got confussed, did look at my sys bin going to change a few things an burn some more gas , it went down to 331 a gallon yesterday.