http://www.gearhead-efi.com/Fuel-Inj...Asynch-fuelingOriginally Posted by Six_Shooter
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http://www.gearhead-efi.com/Fuel-Inj...Asynch-fueling
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1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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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.
The man who says something is impossible, is usually interrupted by the man doing it.
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.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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12.5 milliseconds, very different than 12.5 seconds. ;)
I also have never had success using async in any application.
The man who says something is impossible, is usually interrupted by the man doing it.
Woops!
I'm wondering if Sync Vs Async has same effect on MPFI?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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some times when i am data logging the mpg will go to 6.3 from 12.0 then to 123,its a 747 asyned 6 cylender file,just for an instance then back to normal, thought maybe the egr valve was being commanded to open?
Since most OBD1 MPFI systems only have batch fire, how do you think it would effect it? ;)
I've tried enabling asynch on $59 (Nissan Turbo L28, MPFI) , S_AUJP ($8D, MPFI, 409 style engine, 366 actual, ), $85 (455 olds, with big cam and 4 bbl TBI), and IIRC $OD (305 with Corvette Crossfire intake, TBI), and none of them took well to async.
The biggest reason I can think of is because of timing to intake events. async would rely on fuel deposits left in the intake runners to feed the next intake event. This could lead to fuel puddling and cause uneven fuel mixtures, since the fuel would not be injected with an intake event, as air is being pulled into the cylinder. MPFI does rely on the fuel vapor from the fuel hitting the back of the heated intake valve, but when the injection cycle does not happen at the same time the intake is open, I tend to think that the vapor isn't enough to get nice even fueling to every cylinder.
I'm sure there's a reason to have async, I have just not found an application where it works nicely.
The man who says something is impossible, is usually interrupted by the man doing it.
running MPFI using async as a main fueling model is a horrible idea... Chris hit all of the big points why.
with TBI.... still seems bad, but i can see why it MIGHT work since there is one or two injectors feeding a central location.
still seems like a horrible idea from any standpoint. in software it's a lot easier to calculate for and inject based on DRP than to setup interrupts to turn the injectors on and off. with sync, as soon as the signal from the DRP happens, injectors get turned on for xxx amount of time(which is calculated and updated constantly), shut off, wait for x number of reference pulses to happen and start the process over.
the only time i ever want to see async active is if AE fueling can't get pushed into the sync fueling events.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
I'm starting to wonder why this $0D MPFI conversion is so popular in Async and why it has not been done sync?
MPG gauge is a calculation based off BPW, your's is not correct because of Async. Really need to build a bin for it in Sync...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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I don't remember who it was on TGO, or maybe FSC, that recommended making Async enable at at WOT if you needed more fuel up top, and that you can set it up for that. I have tried a couple of times but never got it to work, I will be trying it again this spring.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
If it needs more fuel it does go Async up top... well normally...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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AE is "async" anyway. What I mean by that is that the AE pulses are added between the sync'd injector pulses. Once I get some time, I'll set up my test bench again and pull some O-scope screen captures to show AE pulses happening between sync pulses.
The man who says something is impossible, is usually interrupted by the man doing it.
It would run like shit, like this one does, there's nothing right about AFR, in Closed loop/idle AFR wanders by 2.xx just like it did on JeepsandGuns $0D MPFI conversion, yet the BLM/INT are close! At cruise BLM/INT climb as AFR is a Zig Zag. There's nothing right about this MPFI conversion in 4 I've seen logs of. Yes you can make it run, but it ain't right! So I still hate Async!!! OK it works good for AE and if needed PE...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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So your saying that the mpfi conversion I did switched it to async? And also there is another one out there and they also had the same wonky AFR as I had? Interesting.
Can it be switched back to sync, and would it run better?
79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy
93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver
99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.
This is just an observation from a 4cyl. $94 with AUXH BIN with single TB injector. It triggered the injector every other DRP at idle and above idle triggered injector every DRP. First screen shot shows the injector triggering change to idle. Second screenshot is idle and third is what happens when a timing light is operating.
Red = Reference
Blue = EST
Green = Injector
Patterns I have seen that show Async during AE continue to use DRP to trigger injector, they just add another pulse between DRP. I know GM training manuals say Async is 12.5 MS but how could that be true if I still see the injector continue to trigger at the same time as DRP? RPM changes wouldn't allow the use of DRP in Async at 12.5 because of injection overlap? IIRC I have checked this on V-8 and 4cyl. I have more patterns at work to demonstrate this.
The 4 cylinder pattern below is just plain goofy. It's triggering like one side of a two injector TBI.
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