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Old 05-10-2007, 11:34 PM   #1
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Default so i got this dumb idea......

so i got this dumb idea today.......

you guys with the old flapper style air meters can get away with running bigger injectors by playing with the clock spring gizmo. its not perfect but works right?

i figured there got to be a way to dick with the latter style air meter. if i put bigger injectors(lets say330s) into my car(97) it will idle like **** and run rich, but if i induce a small vac leak around my air meter,or restrict the air to the hotwire wouldn't this lean it out, because not all of the air is getting metered and the ecu tricked into sending less fuel. this makes sense to me, but what do i know.

can some one tell me why this won't work, and has anybody tried it?
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Old 05-10-2007, 11:38 PM   #2
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Well I'm running the green top supra injectors (305-320cc, depending who you ask) with the same ecu as you with zero issues. It idles slightly rich, but causes no problems.
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Old 05-10-2007, 11:43 PM   #3
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Wouldn't that cause you to lean out at higher rpm?
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Old 05-10-2007, 11:44 PM   #4
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why would it lean out at higher rpm?
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Old 05-10-2007, 11:58 PM   #5
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Air passing by the AFM unmetered, correct amount of fuel not being added. I'm sure leaning at idle would have the same effect at higher rpm? Unless going WOT would just throw in all the fuel. I'm not sure if that is what would happen. Maybe you could put a vacuum operated valve to close off the leak?
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Old 05-11-2007, 01:13 AM   #6
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Quote:
Originally Posted by left field View Post
so i got this dumb idea today.......

you guys with the old flapper style air meters can get away with running bigger injectors by playing with the clock spring gizmo. its not perfect but works right?

i figured there got to be a way to dick with the latter style air meter. if i put bigger injectors(lets say330s) into my car(97) it will idle like **** and run rich, but if i induce a small vac leak around my air meter,or restrict the air to the hotwire wouldn't this lean it out, because not all of the air is getting metered and the ecu tricked into sending less fuel. this makes sense to me, but what do i know.

can some one tell me why this won't work, and has anybody tried it?
How about this, find a larger air meter (say one that's 100% bigger) and throw in 100% bigger injectors. You're more likely to find that this is the answer you are looking for.

Since the formula remains fairly linear, your 100% bigger MAF now shows a reading that is 100% less air flow at a given RPM and load. However since your injectors are commanded to inject less to match you all of a sudden have a car that is capable of fueling 100% more power with no other changes. So if the factory MAF is good for 400 CFM at 4.9v you want a MAF that will flow 800 CFM at 4.9v and some 550cc/min injectors. Maybe a 70 mm MAF from a Mustang.... Hmmm.

Mark
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Old 05-11-2007, 03:00 AM   #7
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Mark you just gave me an erection.
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Old 05-11-2007, 03:02 AM   #8
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Quote:
Originally Posted by Markp View Post
How about this, find a larger air meter (say one that's 100% bigger) and throw in 100% bigger injectors. You're more likely to find that this is the answer you are looking for.
'nother option: Take the guts out of your MAF and dump them into a larger tube. All the cool kids are doing it with OTM's.
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Old 05-11-2007, 03:09 AM   #9
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Been there, done this. The DSM MAF, by design has two passages, one is metered, one is not. The solution to leaning the car out a bit was to enlarge the unmetered portion. Go too far and the car wouldn't idle. So what we'd do is add our own flapper door with a spring that would block the unmetered portion during low load and then get sucked open during high load. It worked well. The 2G MAF didn't allow for this type of modification as much, guys would just put a bipass tube in the turbo inlet pipe after the MAS and use an AFC "in place" of a flapper door. One thing though, DSMs run rich from the factory in all conditions, with stock injectors the modded MAF and flapper door would work great. Some people even had some success going with 550s with and without a flapper. But most people would use an AFC to fine tune things as the modification never resulted in a linear decrease in Karman counts in all situations.

You're on the right track, it'll just take some engineering and thought. Good luck.

EDIT: We also put potentiometers or resistors on the thermistor circuit when doing MAF mods.
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Old 05-11-2007, 03:20 AM   #10
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'nother option: Take the guts out of your MAF and dump them into a larger tube. All the cool kids are doing it with OTM's.
Same idea
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Old 05-11-2007, 10:33 AM   #11
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OTM's ?
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Old 05-11-2007, 12:51 PM   #12
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Dude Mark...hawt. makes me wish I had a MAF. I've got an AFM though and Left Field, after 5,500 RPM my understanding is that the stock ECU is full dumping fuel in.

I do know chelsea DeNofa has a decently high HP miata with out a lot of fancy with just fuel and modified AFM spring
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Old 05-12-2007, 12:35 AM   #13
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http://autospeed.drive.com.au/cms/A_2424/article.html

i think i'll give this a try, when i get some time
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