Playing with afm.
11-26-08, 04:00 PM
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Playing with afm.
Its easy to play with the spring tension, and adjust back to normal with the dmm and pin 2.
Making a small air bypass and loosening the door spring would help the flow i think?
This could make ur car on the lean side. adjust that with afc or resistor at the water thermo switch.
Just an idea. I should try it and measure the vacium difference.
Making a small air bypass and loosening the door spring would help the flow i think?
This could make ur car on the lean side. adjust that with afc or resistor at the water thermo switch.
Just an idea. I should try it and measure the vacium difference.
11-27-08, 09:15 AM
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Screwing with the spring can only change the entire curve, not just one part of it. If you richen it up, the car will be richer across the entire board.
Only very crude tuning can be accomplished via the AFM and tuning it to make the car run nicely at one point will cause all other points to run poorly.
An S-AFC does the same thing but allows you to apply different correction points based on load an RPM. They are cheap on eBay.
Only very crude tuning can be accomplished via the AFM and tuning it to make the car run nicely at one point will cause all other points to run poorly.
An S-AFC does the same thing but allows you to apply different correction points based on load an RPM. They are cheap on eBay.
11-27-08, 09:34 AM
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Seems you should mark one of the teeth on the *gear* and then make a mark just opposite that gear mark. So you can return everything back to it's original position.
I've messed with it before and frankly, just moving one tooth one way or the other makes a marked difference in the way the car runs. But it also requires an adjustment to the air bypass when the teeth are moved so the idle speed can be stabalized. Some of the difference in the running of the engine isn't favorable imho. Nothing wrong with messing around with it as long as you can go back to where you started.
IF you can't go back to the original setting, then it's good to have enough dough to buy another one or have a spare handy.
I've messed with it before and frankly, just moving one tooth one way or the other makes a marked difference in the way the car runs. But it also requires an adjustment to the air bypass when the teeth are moved so the idle speed can be stabalized. Some of the difference in the running of the engine isn't favorable imho. Nothing wrong with messing around with it as long as you can go back to where you started.
IF you can't go back to the original setting, then it's good to have enough dough to buy another one or have a spare handy.
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11-27-08, 12:25 PM
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It made alot of diff on top end.
before i couldnt even feel vdi effect.
I was looking at some dyno graphs and runing richer on top end made more hp vs lean on top end.
WOT is at 1450f with factory timing. before it was 1400f timing advanced 5 deg.
Idle is at 750deg. before 850deg.
before i couldnt even feel vdi effect.
I was looking at some dyno graphs and runing richer on top end made more hp vs lean on top end.
WOT is at 1450f with factory timing. before it was 1400f timing advanced 5 deg.
Idle is at 750deg. before 850deg.
11-27-08, 01:01 PM
#9
The mystery of the prize.
My old Protege had the same type of AFM and I used this technique to fatten up the mixture a slight bit, made a world of difference. More power everywhere, that car was too lean for some reason - bone stock. You could get a similar effect by adjusting the fuel pressure with an aftermarket adjustable regulator, this is just a free means to the same end.
I just turned it a couple teeth at a time between test drives and eventually settled on a new position that seemed to work best, which obviously required reaching the points where the performance and drivability got worse. You eventually locate a sweet spot... once found seal the cover back up with some silicone and enjoy.
I just turned it a couple teeth at a time between test drives and eventually settled on a new position that seemed to work best, which obviously required reaching the points where the performance and drivability got worse. You eventually locate a sweet spot... once found seal the cover back up with some silicone and enjoy.
11-27-08, 01:28 PM
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WOT is at 1450f with factory timing. before it was 1400f timing advanced 5 deg.
Idle is at 750deg. before 850deg.
Idle is at 750deg. before 850deg.
11-27-08, 02:54 PM
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Timing is also effected by the afm. See HENRIK at this thread: https://www.rx7club.com/showthread.p...ght=TIMING+AFM
11-27-08, 10:23 PM
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i calculated that afm is very restrictive.
bore of afm is 1.5 x 2.25" equal to 3.375 sq in surface area.
TB 1.75" batterflys equal to 7.216
my 650 holley 1.5" equal to 7.069 i guess take away for shaft taking space.
bore of afm is 1.5 x 2.25" equal to 3.375 sq in surface area.
TB 1.75" batterflys equal to 7.216
my 650 holley 1.5" equal to 7.069 i guess take away for shaft taking space.
11-28-08, 02:55 PM
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It flows less then 500 cfm, turbo sucking throw it is not the same as n/a .
Why even go stand alone on n/a when you can make fuel curve with afc.
11-28-08, 04:59 PM
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11-28-08, 07:37 PM
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The mystery of the prize.
it's so easy to reverse who cares if you have time and you're curious just go move it around a few teeth back and forth and see what happens. Just mark the ring before you move it if you're really scared... if there's anything good about driving a old 80's high mileage sports car it's the low risk involved in tinkering, if you're not even tinkering why have this car it drinks too much gas isn't terribly fast and tends to need engine rebuilds too often, please tell me it's not your DD and you're afraid of screwing it up. If it is, you've already screwed up selecting the wrong car to sit in traffic with.
11-29-08, 11:00 AM
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That's not a limitation of the AFM though, that's a limitation of how much air the engine can flow at atmospheric pressure.
I think you'd be interested to know that back in the day, it was common to run PP engines with a large plenum using the AFM to run the EFI system. This is because the early speed density systems could not compensate for the wild vacuum fluctuations very well. The plenum and AFM did a much better job of measuring airflow since the AFM measures it directly.
Explain the difference. 
Because a standalone gives you full control that an S-AFC with the stock ECU never will. For example, you can drive the injectors far harder, pull them down far lower, make your own timing curve, apply your own temperature corrections, etc. etc.
I think you'd be interested to know that back in the day, it was common to run PP engines with a large plenum using the AFM to run the EFI system. This is because the early speed density systems could not compensate for the wild vacuum fluctuations very well. The plenum and AFM did a much better job of measuring airflow since the AFM measures it directly.
It flows less then 500 cfm, turbo sucking throw it is not the same as n/a .
Why even go stand alone on n/a when you can make fuel curve with afc.
11-29-08, 11:15 AM
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Clockwise makes the spring stiffer and it takes more force to move the vane aft. Mark a gear tooth relative to the body of the afm if your going to mess around. If you don't, and the gear unwinds................you've become a lost puppy dog.
11-29-08, 11:39 AM
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(Clockwise makes the spring stiffer and it takes more force to move the vane aft) so this would make it rich or lean?
11-29-08, 01:13 PM
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Hailers, it was tested on this forum 380cfm vs s5 420 cfm. 380cfm isnt enought to for 180 engine hp. Restrictive pos. ?
12a mikki carb probably flows 380 cfm.
Kahren did 170sh whp, but didnt state if it was with afm, but using a apexi afc probably means that he did.
But without afm made 25whp extra hp.
11-29-08, 01:23 PM
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Hailers, it was tested on this forum 380cfm vs s5 420 cfm. 380cfm isnt enought to for 180 engine hp. Restrictive pos. ?
12a mikki carb probably flows 380 cfm.
Kahren did 170sh whp, but didnt state if it was with afm, but using a apexi afc probably means that he did.
But without afm made 25whp extra hp.
12a mikki carb probably flows 380 cfm.
Kahren did 170sh whp, but didnt state if it was with afm, but using a apexi afc probably means that he did.
But without afm made 25whp extra hp.
i made 195 with the afm and it would have been more if the injectors didnt run out
here is the link
https://www.rx7club.com/time-slips-dyno-128/na-6port-streetport-dynoed-195whp-update-418805/