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Old 08-30-2007, 02:42 PM   #1
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Default RX-7 AFM ?s

OK so the rx-7 AFM is larger and has better flow and is plug and play on the miata...understood

But does the internal spring gear need to be adjusted to my set-up/miata or can I leave it at the factory rx-7 setting?

Does this effect the air fuel ratio or is the AFR adjusted post AFM at the intake and compensates for the increased air flow?

Is this a worthwhile upgrade, I don't see this item listed on peoples upgrades..
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Old 08-30-2007, 03:53 PM   #2
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The RX-7 AFM does need to be adjusted (tightened) slightly to work on a 1.6 Miata. Go Forth And Search.

Is it worthwhile? It was probably a lot more useful in the days before decent quality piggyback ECUs and Megasquirt, when removing the AFM altogether was not a viable option for most folks.

Your component list (Bipes, Walbro, 1.8 squirters, and presumably a Vortech FPR) is very typical of such a setup. Since you already have a sizeable investment in this gear and probably do not wish to scrap it all and start over, I'd say that the RX-7 AFM, if you can come by one cheaply, might be a worthwhile project. So far as I know nobody has ever posted dyno figures comparing one to a stock AFM on a mildly turbocharged engine, but it can't hurt.

One thing I don't see on your list is a WBO2 sensor. Hath thou any means of measuring the mixture?
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Old 08-30-2007, 04:01 PM   #3
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You can buy mine for 40 shipped
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Old 08-30-2007, 04:33 PM   #4
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Default Rx-7 Afm

Quote:
Originally Posted by Joe Perez View Post
The RX-7 AFM does need to be adjusted (tightened) slightly to work on a 1.6 Miata. Go Forth And Search.

Is it worthwhile? It was probably a lot more useful in the days before decent quality piggyback ECUs and Megasquirt, when removing the AFM altogether was not a viable option for most folks.

Your component list (Bipes, Walbro, 1.8 squirters, and presumably a Vortech FPR) is very typical of such a setup. Since you already have a sizeable investment in this gear and probably do not wish to scrap it all and start over, I'd say that the RX-7 AFM, if you can come by one cheaply, might be a worthwhile project. So far as I know nobody has ever posted dyno figures comparing one to a stock AFM on a mildly turbocharged engine, but it can't hurt.

One thing I don't see on your list is a WBO2 sensor. Hath thou any means of measuring the mixture?

Yes the stock Vortech FPR (I have not played with the discs)...I have a 4 wire O2 but what is a WBO2?

FYI I picked up a rx-7 afm for 15$ but it has been opened up and played with so I don't know where it is suppose to be...
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Old 08-30-2007, 04:42 PM   #5
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WBO2 = Wideband O2 sensor

Search. But the short version is that a WBO2 sensor is capable of giving you a very accurate reading of the fuel mixture across a very broad operating range. Narrowband sensors (such as the stock 1-wire and 4-wire sensors) are accurate only within a small range centered around 14.7:1 AFR.

So a wideband sensor, for instance, can accurately tell you the difference between 13:1 and 12:1, whereas a narrowband sensor will simply read "RICH" for both mixtures.

Examples of popular WBO2 sensors:
http://www.innovatemotorsports.com/x...cat=262&page=2
http://www.aempower.com/ViewCategory.aspx?CategoryID=67
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Old 08-30-2007, 07:30 PM   #6
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Just mess with it until you have your idle and hook up a wideband....
And hay, you owe me
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Old 08-30-2007, 08:37 PM   #7
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Joe,

How do I tell if I have a wideband already installed? (I purchased the car with all the goodies already on it)

Thanx
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Old 08-30-2007, 08:37 PM   #8
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Thanx Pai, I guess you didn't sell your car?
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Old 08-31-2007, 03:57 AM   #9
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Should be a wideband gauge. If you come over ill see if it has one. But usually like a digital meter. HOnestly, if you had one, im sure you would have known about it.
And not yet. But am Kinda trying to, but not.
I mean....
I dont want to sell it, but if someone came with money, i would have to : /
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Old 08-31-2007, 11:56 AM   #10
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Quote:
Originally Posted by Danimal View Post
How do I tell if I have a wideband already installed? (I purchased the car with all the goodies already on it)
Since you don't have a piggyback or aftermarket ECU, any reasonable person would have also installed a wideband gauge. Click the links I posted earlier for an idea as to what they look like.

Alternately, you can trace the exhaust pipe from the downpipe to the cat. The one installed in the downpipe itself near the turbo is the stock narrowband sensor. There would be another one much further downstream.

That said, chances are that you don't have one. Until just very recently they were quite expensive, and if the person who sold you the car had installed one, they'd have gone out of their way to point it out.
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Old 08-31-2007, 03:11 PM   #11
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Thanx Joe aprreciate your help
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