prepping for a swap

**conwaymuddy** · 07-12-2013

Getting ready to swap a tbi into my 93 gmc k1500. Currently running a carbed 454 and th400. Picked up a tbi setup from a late 80's 454 and this is where it gets fun. The guy gave me a 7747 ecm that he thought was for the motor and tbi. Looked up the bcc (ASDU) and its for a small block. So i pulled the original pcm from the truck and its an 8625 with bcc BHAS which i cant find. Truck has tbi wiring from another 93 or 94 i dont remember. So im wondering which ecm/pcm im better off using? I really only need it to run the tbi. I know most use the 7747 but i dont know why. Thoughts or opinions?

**EagleMark** · 07-12-2013

If the truck came with 16168625? Then use it! Don't worry about BHAS, it was superceded twice to BLCR which we may have here:

http://www.gearhead-efi.com/Fuel-Inj...Information-E6

But that is still a 5.7L bin, can be tuned for 7.4L or just start with an $0D bin, most of them work with that PCM, if not a 16197427 will plug into your harness.

**conwaymuddy** · 07-12-2013

Thank you. I had been leaning toward the 8625 since it will require less modification to use. I figure it will be best to reflash the prom to some sort of stock 7.4 tune and work from there. I seem to recall seeing something here about dual fuel and spark tables as well, cant really complain about that.

**conwaymuddy** · 07-13-2013

Best i can tell since i havent heard from my friend yet, looks like the wiring harness is for 94 5.7 auto trans gm based on the pinout. So do i repin the plugs to the 93 pcm or do i have to do something else as the harness and pcm will be running a 7.4 tbi from the late 80's? Im assuming just repin to the pcm but i dont want to start and then redo.

**EagleMark** · 07-13-2013

Unless I'm missing something? No! No repinning, your origanal PCM will work as is, you just need to change the chip/Memcal inside the PCM.

**conwaymuddy** · 07-13-2013

Ok thanks. Was looking through the wiring diagram in the haynes manual for a 94 5.7 4l60e and it matches the harness i have perfect for the pinout. There was nothing specific for 93, just 88-95. Found the 93 diagram on here but its hard to see on a smartphone. Just want to make sure im headed in the right direction.