How to Convert 1990-1992 F bodies to a 1227749 (Syclone) ECM

By Clint Buckalew ( [email protected] )

First let’s start with the question, why would I want to do this? Easy because you’re running forced induction on your third generation F body and want to control and tune with the computer under boost conditions.

Now let’s get a list together of all the stuff we will need to get this project going.

  • Equipment to read and burn chips.(read Traxions article on this)
  • A 1227749 ECM from a 87-90 turbo sunbird, 88 quad 4 car, or 91-93 syclone/typhoon
  • Now for the MAP sensor 2 Bar: GM #16009886, or if you are running a 3 bar calibration 3 Bar: GM #16040749 (requires special modded .bin from STG to run the 3 bar calibration.)
  • And a set of injectors to match

That should be everything you need to get you started. I left little things out like runner to plenum gaskets I’m sure you can figure that stuff out as you go.

Now that we have all of the equipment we need, it’s time to repin our factory ECM connectors. This is what I did for my 91 Z28 5speed car and may not be the best for an automatic car.

730 ECM   749 ECM  
A8 connect to A9 (ALDL data) not necessary
C1 connect to B12 (VSS for cruise)
C11 connect to C12 (Injectors 1,3,5,7)
C12 connect to C11 (Injectors 2,4,6,8)
D6 connect to C13 (Injector ground)
E3 connect to E4 (IAC coil A high)
E4 connect to E3 (IAC coil A low)
E5 connect to E6 (IAC coil B high)
E6 connect to E5 (IAC coil B low)
F1 connect to F4 (shift light) for manual trans
F2 connect to disconnect (AIR pump solenoid)
F6 connect to F4 (TCC) for automatic trans

Next you will have to modify the MAP sensor connector on your wiring harness to accept the 2 (or 3) bar map sensor. I used a dremel tool with a thin grinding disk and grooved the connector fingers so they would plug into the 2 bar map sensor.

Install your larger injectors (sized by using an injector sizing formula) in place of the factory injectors. Any manual made for 3rd generation F bodies should tell you what steps you need to do to change out the injectors.

Now you can remove your FMU or whatever you were using to meter extra fuel into your engine under boost conditions.

Ok we are done with the hardware, so let’s start with the software. You will have to reuse your stock memcal, and get a bin file from a syclone or typhoon and set it to 8 cylinders and modify it to get your motor running well. I used BBZB 1580 as my base file, since it is the latest .bin that GM released for the syclone and typhoon. On my car which still has the stock 305 tpi motor with a D1SC stage II procharger I ran very rich with the factory BBZB programming set to 8 cylinder. I’m sure a 350 tpi motor will be much closer to the factory BBZB VE tables. Now what did you just accomplish by doing all this stuff? You can manipulate your fuel and timing while under boost and data logging programs can now record your runs and give you a complete picture of what your engine is doing. Also you will notice that your cruise control and factory gauges work.

I am not responsible in any way if you fry your entire electrical system or blow your motor up. This is just a guide for those who are looking for alternatives to expensive DFI units.