What are the differences between an S5 N/a and TII AFM?

Can they be interchanged?
Would I have to re-wire it?

Santiago

 

They're physically identical (including wiring), but the spring tension and potentiometer resistance are different, same as for the S4 AFM's. They're calibrated to read the very different flows of the NA and turbo engines, so they should not be interchanged.

 

Yeah I was talking to sonicrat about this. damn I was already lined up to buy an N/a S5 AFM for our 89 TII.

If anyone has an S5 TII AFM in good condition for sale let me know.

 

Helpful hints:

1) Browse through the various ECU sections on this forum, and look for S5 owners who are converting to a standalone EMS. Most people run the EMS in speed-density mode, which means they toss the AFM in the trash (or sell it cheap to lucky people like you). The Microtech group-buy units are being deliveried right now, so I would check that forum first.
https://www.rx7club.com/forum/forumd...ne=&forumid=37

2) Search our classified section:
https://www.rx7club.com/forum/forumd...une=&forumid=6

 

Can I swap spings to decrease the tension in my flapper door? (88 TII) I was playing with it last night and it seems like it takes a fair amount of flow to open it and I was wondering why not replace the spring with one with half the tension?!

 

If you swapped the springs, your afm would give bad readings. Think about it, the position of the flapper door is dependant on how much air the engine is sucking in. A looser spring would cause it to open sooner when its using less air, and you'd just run rich.

 

They should not be interchanged, BUT they can be. I know NZConvertible is strongly against running the S5 AFM in an S4 application for the reasons listed above, but it can be done.

In my 86 NA, I had a bad AFM. So I replaced it with what I had available...An S5 AFM. The rewire is very simple. (Just search)

The drawback? I recently ran the S4 and S5 AFM's back to back on the dyno last month. The S5 AFM showed a 1RWHP gain across the board and the graph was significantly smoother. The problem was that I had to add more fuel with my Super-AFC because the S5 AFM leaned out the mix across the entire RPM range.

Oh: when you rewire the S5 AFM into the car, you loose the Fuel pump saftey switch!!! IF you roll your car, and the engine stalls, the fuel pump will continue to run!!! So if you do this mod, DON'T CRASH!

 

wozzoom- Thats neat but I was talking about N/a to TII both S5 not S5 to S4. Anyone tried that? I can probably still buy that one if he holds if for me. ????

 

Compare the AFM resistance values in Chapter 4A F1-82, and 4B F2-80 of the Factory Service Manual, and you will see that they are not the same.