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chiefmd

AFM switch

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I have a76 280Z refurbished AFM (from MSA) that has only been on the car for a couple of months. I'd like to put on my 77 280Z. It is a 7 pin 3 hole mount and looks exactly the same as my current AFM that's on the car.

It has a tag with " FUEL INJECTION CORPORATION " and the #170348.

 

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Assuming you are asking if you should or not, go for it.

Only the 78 has a unique AFM without the internal fuel pump switch. 

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Yes, it will work. All afm's before Aug 1977 will work fine.

Like zKars said, the ones after July 1977 on the 280Z and 280ZX don't have the fuel pump switch. Thay also have the seven pin connector, but miss two pins.

AFM-1.png

Edited by EuroDat
Photo

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Thanks Eurodat. I remember reading somewhere that 75 and 76 were interchangeable but they could be used on a 77 but would need to be recalibrated.  If so are the any sites that might show you how to. Thanks

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The ONLY website I can recommend for doing any kind of adjustment to the afm is atlanticz. Many thanks to @240260280z for putting in all the effort and sharing.

http://www.atlanticz.ca/zclub/techtips/afm/index.html

http://www.atlanticz.ca/zclub/techtips/

One piece of advice. I have four of these afm's, all from different years 1976 to 1982 and only one was off (given some tolerences in meassuring) when I followed the steps mentioned in the "water calibration". The glue on the screw was also clearly tampered with. Someone had played with it before. Do the water calibration CHECK before you start adjusting.

Btw: Contrary to what some people my think, this is not aperformance adjustment. It will make the engine run in tune, but decreasing the spring tension to mislead the ecu won't give you more horsepower. If you have problems with "ECU drift", there is a modification in the temperature sensor resistance to compensate for that.

The only real differences I know of in the 75 to 77 AFM's is the blow back valve in the early version/Fed version. The very early 12-74 to 06-75 are actually Bosch units.

Some photo's of one of my afm's and the calibration check.

IMG_0154.JPG

IMG_0161.JPG

IMG_0159.JPG

Edited by EuroDat
Adddd differences in early version
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Royal Club Shandy:   Beer Advocate's rating?   1.65 out of 5  (Awful)

Sounds like the perfect beverage to use for the AFM calibration check!  LOL

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Here’s a good Z AFM video I watched some time ago that I found educational.





Sent from my iPhone using Tapatalk

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19 hours ago, chiefmd said:

Thanks Eurodat. I remember reading somewhere that 75 and 76 were interchangeable but they could be used on a 77 but would need to be recalibrated.  If so are the any sites that might show you how to. Thanks

I don't think that Nissan changed the calibration of the AFMs over the 280Z years.  The engines are essentially identical.  And the atlanticz calibration procedure is not year specific so it won't help, unless somebody else messed with it and you want to get back to spec.  And, I have a 1978 AFM that has the fuel pump contact switch.  It's just not used.  The 1978 wiring diagram even shows it but labels it as "useless".   

Anyway, if it's a new MSA refurb product you probably don't want to mess with it.  Just put it on and run it.  Mess with it if it has problems.

image.png

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I have several AFMs that I picked up over the past year to have backups. When I was investigating my idle problems I decided to try one of my backup AFMs on my car that successfully past the bench tests. What I discovered was the my 77 has a different mount bolt pattern than the 76 AFM I pulled out of a yard. Has anyone else seen this?


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Yes, the bolt pattern is a known thing.  MSA mentions it, and shows the other bracket on the bottom of their AFM page.  I've seen people zip tie them in place.

Somebody with free time, a leaf blower, a battery, and a meter must have the urge to compare AFM's.  

https://www.thezstore.com/page/TZS/PROD/11-3040

 

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The three bolt pattern version is most probably the early bosch type. Or they are using 3.0L Alfa, Mercedes, Pergeot, Opel AFM's as cores.

20181227_230652.png

20181227_230616.png

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Really appreciate all the input. I think I'll just perform the basic pin/ohm checks and if all checks out install and see what happens. Again thanks

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I had heard that the sweep style of the later AFM's was different than the earlier ones... Something like the ZX's used a logarithmic sweep for the voltage while the earlier Z's used a linear output?

I have no input as to the validity of that, but I think I read it on the internets.

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Seems reasonable.  The ZX's used a different ECU also.

I wonder if the circuit boards inside might be the same.  Something we can compare without too much trouble.  Probably have numbers.

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Here's a start.  An A31 060 001 from a 1975 280Z, I think.  Kind of looks like a Bosch part number on the board, but it says OHMIC.  1 288 310 011 with a big 7444 beside it.

image.png

image.png

 

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13 hours ago, Zed Head said:

board, says OHMIC.  1 288 310 011 with a big 7444 beside it.

I suspect OHMIC is a company that Bosch sub-contracted out to for construction of the board. I bet that Bosch did not silk screened their own boards.

And the 7444 is probably a date code for 44th week of 74 (making it a prime candidate for the 75 model year).

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It's a bosch unit. That is a Bosch symbol next to the "+" symbol. I think OHMIC desrcibes the type of contact used to measure resistence and therefore vane position.

"Generally the term "ohmic contact" implicitly refers to an ohmic contact of a metal to a semiconductor, where achieving ohmic behaviour is possible but requires careful technique"

https://en.m.wikipedia.org/wiki/Ohmic_contact

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The AFM cover was the typical green Nissan label.  If later AFM's use the same board the odds are good, I think, that the "tuning" is the same.  Anybody got a 1978 handy?  I think I sent mine to @rcb280z

I have an MSA AFM on my car now.  MSA says that Fuel Injection Corp. uses a thicker material on the conductive pattern to make it more durable.

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Chiefmd, I think "if" you need to do anything to the refurbished unit, after installing on your 77, it will just be an adjustment on the "idle air screw" at the bottom of the AFM.

This is assuming it hasn't been opened and molested. 

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1 hour ago, rcb280z said:

Zed Head, the one I got from you has the 7 pins and fuel pump cut off so I assume its a 77.

It's a 78, pretty sure, I got it from a 1978 parts car that seemed all original.  The fuel pump pins are "useless" as I showed above, post #8, with the Nissan wiring diagram.  Nissan probably had old AFM's in stock when they made the model switch.

If you can get the part number from the board that would be cool.  No picture necessary, although pictures do add something.

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It has the fuel pump cut off inside. It worked on my 77 when I tested it otherwise I would not have used it.

Here's a pic of the board.

 

 

board.jpg

Edited by rcb280z

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Thanks,  looks like it has the Nissan A31 number, along with an extra number.  No simple Bosch number comparisons.  Dang.

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Here's a pic of the AFM in my 77. I haven't owned the car since new so I can't guarantee that it's original, but I believe it is:
P1100253.JPG

Seems the later AFM's used the green protective screen printed coating over the laser trimmed resistors.

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