Below is a writeup on the 7730 conversion, used with permission of Ryan Gick, developer of the Digital EGR Adapter we produce.
This information was updated in an email to Georgia Fieros on January 5, 2014.
A friend of mine brought me his Fiero to have a swap done. He had a very high mileage stock 2.8 and 125-C and wanted me to swap in a lower mileage 2.8 and 440-T4 OD transmission. Not content with sticking with the stock 2.8 ECM, I convinced him to swap out ECMs during the swap as well. In short, it was an excellent choice!
The ECM that was used in this swap was the 1227730 unit which was used in many 1987-92 era GM cars. For this application, I elected to use the $88 code mask programming which was designed to be used in a 1990-92 Camaro/Firebird 3.1. The Camaro/Firebird 3.1 is very similar to the stock Fiero 2.8 including it's use of a distributor and iron-heads. With that being said, there were some significant differences between the two systems...
The 7730 ECM running $88 code mask does NOT use or need the 7th injector (cold start).
The 7730 ECM controls the coolant fan relay directly.
The 7730 ECM will interface with stock Fiero 2.8 ECM wiring harness. (although some modifications will be needed)
The 7730 ECM uses a knock sensor.
The 7730 ECM interfaces directly with the speed sensor which means changes can be made in the programming to calibrate the speedo without having to change out the plastic gears on the VSS sensor itself.
The 7730 ECM running the $88 code mask will NOT work with the stock Fiero 2.8 EGR valve. It is designed to work with the digital EGR valve used in the early-mid 90's era GM V6 cars. I went ahead and designed an adapter plate and had another Fiero friend make one up so we could use the digital EGR valve on the stock Fiero 2.8 y-pipe.
The biggest advantage to using the 7730 ECM in a Fiero application is not only more tunable options in the programming, but the driveability and response time of the engine improved significantly. Gone was the unstable idle characteristics of the stock 2.8 which some have said existed from the factory. Gone was the high idle flare upon startup. We quickly found out that using the 7730 ECM system on the stock 2.8 greatly improved it's driveability as well as throttle response and performance characteristics. Believe it or not, using the newer computer, even this stock 2.8 ran and acted like a new engine found in today's new cars! And because the 7th injector, fan switches, and vacuum-controlled EGR valve were no longer required, it also allowed us to clean up the wiring and vacuum lines on the stock 2.8 engine as well...
I think this is one of the most worthwhile upgrades for a stock (or even modded) 2.8. Obviously, it can also be used on 3.1 and 3.4 OHV swaps. Although if you are swapping in a newer 3.1 or 3.4 that has provisions for the DIS ignition system, I would recommend using the DIS as well. The 7730 ECM will work with the DIS ignition system if you use a different code mask (programming).
But be aware that I have made some changes in the way I tune things that will affect the viability of (a highly modded engine).
Any Fiero using a stock iron-head 2.8, iron-head 3.1, or iron-head 3.4 will still be able to make use of the 7730 ECM upgrade using the $88 (distributor) and $A1 (DIS) code masks – both of which will require the use of (the) digital EGR adapter plate.
However, for highly modded iron-head engines, I’m now recommending using the 7730 ECM with the 8D mask which won’t work with a digital EGR (but will work with the stock Fiero EGR).
The reason for this “update” is because the V6 masks ($88 and $A1) used in the 7730 ECM have some nasty limitations in them that prevent them from being able to work well with highly modded engines.
Sinister Performance, LLC.
Fort Wayne, Indiana USA