i'm not sure how to write this up but Ill try my best. For the ecu swap I had a friend in Japan get me a VPC harness and the 3rd gen mr2 ecu for less than $200. That is why I went along with this mod. I did this with the intent to get a power fc and plug and play it down the line. The wiring is not all that difficult if you have a 92-93 st185. I have a 90 BGB and rewired it according to that at first but the car wouldnt start. I later sourced a 93 wiring diagram and it was almost identical to my 92. I used the wired for the egr to wire in the air intake temp sensor on the manifold. As for the AIT sensor on the airbox i used the wires from the afm. I have 550s in my car and yes I believe the 3rd gen came with 550s stock. However, Robert theorized that using the 440s may work with the st185 map sensor. Since the st185 map sensor cuts out at 17psi and the 3rd gen cuts out at 23psi or so. Using the stock map sensor will make the car run richer with on the 3rd gen ecu which in turn can be offset (leaned out) by using the 440s. I went and bought the 3rd gen map sensor (it was $280!!!). I also went along with a GM air intake temp sensor instead of the 3rd gen one since I couldnt source the right part #. I am going to try and use the one off the 5sfe soon. As for now I leaned out the fuel curve alot with the safc and advanced the timing. The fpr is set at 40psi. I belive the car is running rich and retarted timing since I am using the GM AIT sensor. The car is running pretty good right now. I dont plan to anything more till I get the power fc. I hope this helps. One thing I must add is that since my car is not stock results may vary individually from car to car. here is a list of my mods:
50 trim ct26, sard fpr with dual feed fuel rail mod, safc, 3rd gen ecu, ARP everything, JE 87mm pistons, Eagle rods, TT# 1.6mm HG, Sard BOV, 23X12" Griffin FMIC, Apex intake, Topend 3" DP, homemade 3" piping to the rear axle with HKS rear section (2.5"), ACT street clutch, Greddy profec B, Earl's oil cooler and oil filter relocator (mounted but not plumbed yet), etc + other non performance mods.
John So 92 st185
03 g35 coupe