Possible AFM upgrade

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Marc
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Possible AFM upgrade

Post by Marc » Tue Apr 03, 2007 12:41 pm

Nippondenso air flow meter as a possible upgrade.I have an afm fom a 280 Z with the exact pin replacement connection and same size passage.Lets take a look at this...It can flow a 6 cylynder engine (2.8) litr.Calibration must be different.lets hear from all of you about this who can shed some light on this subject.

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Kevin1
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Post by Kevin1 » Tue Apr 03, 2007 8:24 pm

Marc,

All I have been able to find so far is the fact that the two AFM's don't seem to share part numbers from either of the manufacturers of replacements I've found so far. Beck Arnley and Standard both make an AFM for both carsm and they have different part numbers. So far I haven't been able to find specs to compare.

Did Bosch make the originals for both applications?
Kevin Rich
1980 Spider 2000
1962 Austin Healey Sebring
1976 Lancia Scorpion (SOLD)

JimFierst
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Post by JimFierst » Sun Apr 08, 2007 5:28 pm

Based on measurements that I have personally taken the 280 AFM & throttle plate areas they are the same size as the Fiat . All the Bosch L Jetronic systems Fiat, 280, Alfa 164 and probably Volvo,have the same size throttle plates ,around 2 to 2.25 inches. More impotrtantly the area of the flap in the AFM is the same size ,approximately 2 x 1.8,or 3.6 square inches. These units appeared to be matched so that the AFM opens proportional to the throttle plate. As I understand it the AFM measures the angle of the vane through the resistors to send the air flow signal to the ECU. Simply stated they are a matched pair . If you were to get a bigger AFM from a BMW or what ever the vane would not be activated as much as the throttle plate and the signal sent would indicate a lean mixture. As The Alfa produces more horse power out of the same size throttle plate and AFM I don't think the AFM is the performance limiter on a Fiat FI.I am at 140+ HP in the Turbo Spider using the stock system. I know it seems strange as you would think they should be different but if you get some of the components and measure them you will see no real difference.
1982 Fiat Spider; Turbo'd &WHOA Brakes Equip'd
1979 Lancia Beta Zagato, Performanced enhanced example of the breed

Marc
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AFM

Post by Marc » Tue Apr 10, 2007 8:57 am

Hi Jim,
I am working on it in the next few weeks.The nippondenso unit I have size wise,is physically larger than the Fiat unit,but smaller than the 3.6 jag unit.i will take some pics and e-Mail you.I am glad you have some expeience with them.By the way ,do you know the throttle body diameter differences between the alfa unit and your unit?

JimFierst
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Post by JimFierst » Tue Apr 10, 2007 9:21 am

The physical size of the 280 is larger as is the Alfa. The place to measure is the passage way for the air flow which is about 2.0 X 1.8 inches.
Using the Alfa came up some years back and some one did measure it and the Fiat and found they were the same.
If anyone has an X1/9 AFM it would be good to see what they measure as well.
1982 Fiat Spider; Turbo'd &WHOA Brakes Equip'd
1979 Lancia Beta Zagato, Performanced enhanced example of the breed

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racydave
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Post by racydave » Tue Apr 10, 2007 5:47 pm

If someone has had better sucess with a different air flow sensor, perhaps the difference is in the sensor itself. I know these are picky devices, I took 2 days to diagnose one all because it had a fuzzy cottonseed stuck in it. Gm states these are used to provide a stoichiometric ratio (14.7 parts air to 1 part fuel) along with input from eng temp and RPMs, are calculated by the computer. The sensor is also capable of compensating for altitude and humidity. This is done by measuring the voltage required to maintain the temperature sensing element at a given temp above the incoming air flow. I dont know that the Bosch idea is different, but it probably achieves the same result. Installing the incorrect part could ultimatly lead to computer damage. Does anyone have Fiat specific info? Or a good connection to Bosch?
1979 spider 2000

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racydave
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Post by racydave » Wed Apr 18, 2007 5:11 pm

On the Bosch L-Jetronic Fuel injection the air flow sensor is a spring loaded flap connected to a potentiomiter. The ECU reads voltage variations. There is probably a procedure to check them. Besides having a proper air flow, the flap needs to move freely, and the spring should return properly. Of course torn boots cause a problem. I could see where these were probably used on other vehicles as well. I would not recomend messin with the springs, but I wont tell you not to. Thoes springs are 25 years old... Ill search for any testing procedure for the sensor.
1979 spider 2000

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allenlofland
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Post by allenlofland » Wed Apr 18, 2007 6:21 pm

Allen & Lynette Lofland
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Back on Land with Our Fiat :)

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jseabolt
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Re: Possible AFM upgrade

Post by jseabolt » Fri Apr 01, 2011 4:17 am

Marc wrote:Nippondenso air flow meter as a possible upgrade.I have an afm fom a 280 Z with the exact pin replacement connection and same size passage.Lets take a look at this...It can flow a 6 cylynder engine (2.8) litr.Calibration must be different.lets hear from all of you about this who can shed some light on this subject.
Something else to consider. Joe Serra at FFO 98 told me an AFM from a 280Z was an upgrade but when I found a 280Z in a junkyard I noticed the Z car had a smaller throttle plate than the Spider. I can't remember right off hand the measurements but it was noticably smaller just from looking at it.

So the 2.8 liter Z car has a bigger AFM but a smaller throttle plate but it's the opposite on a 2.0 liter Fiat.

Just from past experiences with intake systems, if you can do away with the corrigated rubber hose and go with a smooth intake pipe, this helps increase air flow velocity.

This worked very well on a 1994 Jeep Wrangler and somewhat on my Subaru. But the air intake noise is herendous under wide open throttle. It's my understanding the corrigation in the hose is to increase turbulence which reduces intake noise. The downside is you hear then engine moan under wide open throttle. The Subaru also has this bulky resonator box.

Here's some pics:

http://s222.photobucket.com/albums/dd14 ... at/Subaru/
1980 Fiat "turbo" Spider
1987 Yugo GV "turbo"
1980 Brava 4 door

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KevinB
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Post by KevinB » Fri Apr 01, 2011 7:15 am

1st gen, 13b RX7 AFM

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X1-9 beside RX7 ND unit
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85 Bertone (24k orig miles)

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