Someone here has done it....RX7 AFM - fitting the mx5 spring

[Uncle Arthur]

I know there's a post/thread here somewhere about this (or perhaps it's in the archives), but who's done it, how did you do it, and what were the results?

[StanTheMan]

I believe King Matty was doing some research on it. It may have turned out to be the same spring.....


Calling King Matty......

[hillsend]

When I installed my RX7 AFM, I found the spring was a lot stronger than the standard one.

On the standard AFM I removed the cover and connected a volt meter to the arm and recorded the voltage at different revs eg 1000rpm 3v, 2000rpm 2.5v etc.

Then I installed the RX7 AFM and checked the voltage and turned the spring untill the voltage at 1000rpm was the same as standard but all other voltages were wrong.

So I unbolted the arm in the RX7 AFM, undid the 3 screws and changed the spring to the standard one.

I adjusted the spring and the adjustment on the arm untill the voltages are almost the same and the car runs perfectly.

This is the basics it is not very difficult, at the time I had a wideband O2 sensor. If you don't have one or access to one be very careful you don't lean the mixture out to much.