Synch vs Asynch fueling

[1project2many]

EDIT EagleMark: Question moved from another thread.

Synch vs Asynch fueling...

Synch fires with DRP. There may be a time delay, but it's DRP--Inj DRP--Inj. Asynch uses a strange method with an accumulator and an internal timer. Each time the code wants some type of quickie extra fuel it sends a request for asynch fuel to the accumulator. If the requested injector on time is less than the minimum asynch pulse value, the request is held in the accumulator. Once the accumulator value is equal to or greater than minimum asynch value, the injector is pulsed on the next cycle of the internal timer and the accumulator is reset. DRP has nothing to do with this one. If the accumulator value = (or is greater than) minimum asynch pulse, the injector is triggered.

[EagleMark]

Thanks 1project2 many!

That is strange? I had it wrong as I thought async was both injectors each DRP and Sycn alternated injectores each DRP. Or is that still the case? I can see where async could provide extra fuel if need be, but how would this ever be used at idle, or like I mentioned in other bins that async is always on?

[1project2many]

Asynch will fire both injectors. For asynch at idle look at AE and stall saver. The Corvair has low vacuum so if there's enough of a change that the ecm thinks the engine's loading up, it might call for AE. Or if there's enough of a surge in idle speed the stall saver might become active. Stall saver usually comes with a bunch of spark advance as well so use that as a clue. I don't believe asynch is ever always on. I think the checkbox allows or prevents asynch at idle. Have you got a mask / cal and maybe I can look through code??

[EagleMark]

We already fixed the Corvair, he started with a fresh bin and idles great now. Besides a lot of things checked and unchecked wrong there was a lot of Items Not Defined, so I don't know what the issue was but it's good now.

I moved this to a seperate post for info.

I don't believe asynch is ever always on.

That was my thought, but I have V6 7747 bins that Async is always on, they run horrible so I took a V8 bin I knew was Sync and made it a 6 and they run great, this was on I6 conversions. I was wondering if there was a reason a V6 needed Async?

One of those bins (AKSF and AKSK) that runs Async always on is in ony's thread on Lean Cruise, it was a superceded bin and now that he has the updated bin he says it runs much better but I have not seen data yet to see if it is now Sync. I'm very curious...

[EagleMark]

Ony got the data from the updated bin and it's still Async all the time... just don't understand why they would do this on a 7747 V6 cal? The Corviar is running a 97427 V6 cal and it is Sync. Is there a change in V6 engines?

Then I remembered some? 7747 4.3L had 2 differant size injectors? That alone has always baffled me...

[1project2many]

I'm not sure what you're looking at. Which location? Which TP definition file? I've looked in TP and TC and I don't see a selection for what you're describing.

[Six_Shooter]

Why is there such confusion over sync and async fueling?

It's simple, sync fueling is the injectors pules WITH the DRP input, or at least in equal proportions. There will be some propagation delay between DRP input and injector pulses.

Async fueling pulses the injectors every 12.5 msec, regardless of number or frequency of DRP.

It has nothing to do with bank to bank or batch firing.

[EagleMark]

Why is there such confusion over sync and async fueling?

It's simple, sync fueling is the injectors pules WITH the DRP input, or at least in equal proportions. There will be some propagation delay between DRP input and injector pulses.

Async fueling pulses the injectors every 12.5 msec, regardless of number or frequency of DRP.

It has nothing to do with bank to bank or batch firing.

Well that's one part... TBI Sync is each injector firing alternatly, Async they are firing together. TBI to MPFI conversion changes to Async/Batch, Sync/Bank...

[Six_Shooter]

Well that's one part... TBI Sync is each injector firing alternatly, Async they are firing together. TBI to MPFI conversion changes to Async/Batch, Sync/Bank...

Not in any information I've ever looked into. Regardless of induction/fuel delivery scheme, the sync and async mean, or act exactly the same way. With DRP, or 12.5msec apart.

[EagleMark]

Not in any information I've ever looked into. Regardless of induction/fuel delivery scheme, the sync and async mean, or act exactly the same way. With DRP, or 12.5msec apart.

http://www.gearhead-efi.com/Fuel-Inj...Asynch-fueling

Page 2...

[Six_Shooter]

http://www.gearhead-efi.com/Fuel-Inj...Asynch-fueling

Page 2...

Read Ronny's post again. Though it may seem like he saying that sync and async change the way the injectors are firing he is, it's with DRP or every 12.5msec. IIRC the hardware does not allow both injectors to fire at the same time.

Read through some of the sync and async stuff posted on TGO, the firing pattern does not change.

[EagleMark]

I may strip the Asycn/Sync to the other thread, both this AND 10 degrees are important.

One of these days it will sink in... for me the bottom line is how's the car run? Never has a TBI ran well or tuned well with an Async bin. ALways has a TBI ran well and tuned well with a SYnc bin. Done this and redone this on same car and results are always the same.

If Sync is to DRP then it's timed to engine, Async is every 12.5 seconds? Then it stacks up, saves overflow, uses or clears and starts again.

[chevmasta]

I was reviewing my last log see attached. Engine Runtime of 358 seconds. I was 100% throttle and the ASYNC Flag showed Yes. The ASYC BPW stayed at 0.00 while I was at WOT.
The ASYNC BPW shows a number virtually all other times than 100% throttle........when the ASYNC Flag isn't "yes". Take a look at the log.

This is a bin that the ASYNC is supposedly turned off.

My "BPW" is about 7.00ms during much of the WOT run in this 7.4l
I also had my "BPC" set to 140..........vs the BANC.bin of 142.

[EagleMark]

That's funny! Your Asnc is set off yet it comes on, my Asnc is set on and it won't come on!

I'll look at your log later and add an Injector Duty Cycle % value. With that and BPW times you should try the stock BPC and calculated BPC to new fuel pressure and see what happens.

FYI the pictures above are a stock engine and stock pressure yest shows 110% duty cycle. All these TBI systems are marginal (short) of fuel to begin with.

Anyone reading this! Every Injector Duty Cycle % value I have found in all ADX files is WRONG! It's only half! $42, $0D etc... 49% = 98%... Static!

[chevmasta]

With that and BPW times you should try the stock BPC and calculated BPC to new fuel pressure and see what happens.

FYI the pictures above are a stock engine and stock pressure yest shows 110% duty cycle. All these TBI systems are marginal (short) of fuel to begin with.

Anyone reading this! Every Injector Duty Cycle % value I have found in all ADX files is WRONG! It's only half! $42, $0D etc... 49% = 98%... Static!

I already tried the calculation with the fuel pressure........we came up with about 120.

I was lean at idle........and lean up top.
150-155BLM values with nothing else touched other than lowering the BPC from 142-120.