well i have an 84 supra, and it had the same looking AFM as that one in the pics of that link's link. I currently do not have a MK2 supra AFM, my supra runs a standalone sys... however, now this has sparked me to think of something like this. if the connector is the same...:). but this makes no sense.. b/c the mk2 supras have 2.8L I6's. mine is a V6 3.0.... so you'd think the bigger engine has the bigger AFM. But, if i can get a Supra AFM, and boost some HP..:) we really need to work on this guys. I'm determined to help. I'm gonna pull my '84 supra "TOYOTA" manual out and it shows the pin out of the AFM and what it is, and values to check it etc. I'll get on that ASAP tomorrow. I'm also gonna pick up an AFM off an MK2 from the junk yard and 98% sure I can make this work. Also, the mk2 AFM is "adjustable" to a degree. I adjusted mine 4 teeth internally due to the mods I had..ran better. Let's figure out how to put a "large" AFM on the 90-95 3.0V6. that's the goal.
Here's the deal: the circuit board inside the AFM is matched to each engine's air flow.
Toyota used the larger bodied AFM on some motors and not on others, even though the combined injector flow rate was similar when totaled. For example, the 5MGE Supras and Cressidas use six 195 cc/min injectors for a total flow of 1170 cc/min. These motors got the larger AFM. The 22RTE, on the other hand, uses four 295 cc/min injectors, for a total flow of 1180 cc/min, and this motor got the smaller AFM.
Another wrinkle: the only large bodied AFM that can be considered plug and play is the AFM used on the 1982 5MGE Supra (and maybe the Cressida from the same year, but definitely the Supra). The reason is that the 1982 Supra's air flow meter produced an output signal that went from low -> high (~2V-~8V). The 1983 and later 5MGE AFMs look identical, but their internal electronics produce a signal that goes from high -> low. This is obviously a bad idea on a motor that originally used an AFM with an oppositely oriented signal, as it will go full lean at WOT.
If you are committed to doing this swap, the solution is to use the larger bodied AFM and swap over the traceboard (aka, the resistor, PCB, etc.) from your current motor. It isn't perfect, but it's about as good as you can do.
Finally, keep in mind that the small bodied AFM is only a restriction if you are saturating it at WOT. Because the AFM measures air and the ECU is calibrated to associate a given "AFM vane angle" with a particular amount of air flow, switching to an AFM that will flow 20% more air for a given vane angle (which is approximately what the 5MGE AFM will do) can only be supported if you also switch to larger injectors AND tighten the spring on the AFM (1 tooth = about a 2% reduction in fuel). Just switching to a larger AFM and not re-tuning will only serve to lean out your mixture. Once you re-tune, you are still back in the same boat, as the motor should only need
x amount of air at a given engine load, regardless of AFM door size. Again, a larger AFM is only a benefit is you exceed the flow capacity of the stock AFM. It takes about 160-170 rwhp to reach this level of air flow, and you're probably not going to see that unless you are using a turbo.
Just some things to chew on...
-Jeff
