Fiero computer swap Questions PICS

[3XTurboAgain]

I need to know how to put a 3.1 computer in this car. The 2.8/th125 is coming out and i would like to tackle the computer layout while the engines being built. It's going to be turbocharged w/ MPFI computer.

[IMG][/IMG]
The first picture has 2 black plugs and a white square plug. The 2 black ones came from the computer and there are 2 black plugs that come from the center console that the White square plug came from. Picture 2 shows the center console plugs.

Does anyone know where i go from here? Is this for sensors and switched igntion, gauges, to the dash? I imagine i drop the whole harness in, hook up the constant power and splice certain pin # from back of 3.1 computer to everything else? gauges, switched ignition, fan relays, check engine light... i need help so we're just trying to absorb as much info as possible on the computer swap.

[2.8RS]

You can run the 3.1 with a 2.8 computer. I will be doing it. The harness is different in a couple of places. The 3.1 is MAP and the 2.8 is MAF so the harness is different. You may have to swap the harness too if you go that route.

[sharkey]

2.8l in the fiero is not maf, its speed dencity with a map sensor.

[3XTurboAgain]

Im trying to get rid of the whole distributor deal... need to run a crank sensor and coil packs like a 1990 FWD 3.1 so i dont see any way to use the 86 fiero GT computer or engine harness...Im actually using a 99 3400 top end with a Turbo grand prix chip ive had lying around. there obviously has to be a decent amount of wire splicing to get this computer hooked up...right? will someone step forward here?! I know its been done and i dont think there are any writeups because it was either such a pain in the ass or it was way too easy... thanks guys

[sharkey]

pretty much you need to hack the stock pcm plugs off and wire the 7730 ecm plugs onto your harness. the best way to do it is get wiring diagrams for both , and one at a time pull the pin out of the fiero plug and put it in the correct spot on the 7730 plugs. its time consuming, but the best way.

you can run your stock computer with dis, the gm dis has the same connections at the computer as the distributor does. with a little bit of tuning, it works fine.

[3XTurboAgain]

OK, will i have to splice less wires if i use the new wiring harness with the 7730? Otherwise, using the fiero harness is going to make for a lot more splicing...right? I have the pin layouts for both computers im just trying to make it as straight forward as possible. By the way thanks for the help everyone.

[85maro]

Don't get scared off by harness repinning, I converted my '870 to a '165 and it wasn't a hard swap. Hardest thing so far has been trying to understand the dissasembly of $1F (the '870 mask) I had to do to find the stock maf scalars.

Save yourself some $$ and repin it. You can use the Fiero harness, just run the dist. (rpm signal) wires to the crank sensor. I assume you are using a 3x00 block & crank? Otherwise a crank sensor is pointless.

[3XTurboAgain]

OK guys im really new to this so please bare with me...i have the whole engine harness out now. Wait so the plugs for the crappy distributor are the same for the ICM? i dont understand... if i remember correctly , the ICM has 3 plugs. one for crank sensor, power,...and a 3 wire plug i think... Sorry im just a bit confused, im just tryin to get through all this. Thanks

[85maro]

There should 2 plugs on the ignition module. The pinouts for the rpm signal wires should be the same on the 3.1 and fiero ecms. Are you using a 3x00 block and crank? Otherwise you'll need to have the block machined to use the dis crank and sensor.

[3XTurboAgain]

Im using a 3.1 block from a 1991. Heres what i found so far.

1988 Fiero GT
A1 Fuel Pump
A2
A3
A4 EGR Valve
A5 SES light
A6 IGN
A7 TCC or Shift LT
A8 Serial data
A9 Diag Term
A10 VSS input
A11 MAT sig
A12 GND
B1 Battery
B2
B3 EST ref Low
B4 EST CTRL
B5 Dist Ref
B6
B7
B8 A/C clutch sig
B9
B10 P/N SW
B11
B12

C1
C2 A/C relay control
C3 IAC "B" Low
C4 IAC "B" high
C5 IAC "A" high
C6 IAC "A" low
C7
C8
C9
C10 Coolant Sig
C11 MAP sig
C12 Map Sig
C13 TPS sig
C14 5V ref
C15 Inj 2,4,6 "B"
C16 Battery
D1 SYS GND
D5 EST Bypass
D6 O2 ground
D7 O2 sig
D8 EGR Diag SW
D12 CLTS-TPS ground
D13 Map-Mat ground
D14 Inj 1,3,5 "A"
D15 Inj 1,3,5 "A"
D16 Inj 2,4,6 "B"

[3XTurboAgain]

1991 3.1L ECM wiring
1 IAC
2 IAC
3 H/D Cooling fan relay
4 EGR sol (A) control
7 IAC
8 IAC
9 Cooling fan control
10 Canister purge
11 Detonation Sensor
12 A/c comp Ctrl
16 O2 sensor high
19 EGR sol (B) control
20 Fuel pump relay Mon
22 O2 sensor low

1 SES ind control
3 Diag Input
5 Data in/out
7 TCC
8 SPD SENS output
10 Ign power

2 VSS input
3 Bypass control
4 IAT sensor Input
5 Sensor ground
6 Ground
7 5v Reg (MAP and A/C Pres Tran)
8 VSS input
9 Spark Timing
10 Sensor Ground
12 5V ref TPS
13 EGR sol (c) control
14
15 TPS input
16 Coolant temp input
17 A/C on input
20 2nd Gear input
21 A/C Pres Sig
22 MAP input

3 INJ control
4 Ground
6 3rd Gear input
7 Fuel pump relay
9 Inj control
10 Ground
11 Trans PostN input
12 Ground
13 Dis Pulse Ref hi
16 P/S pres input
17 Battery power
19 DIS PULSE Ref Lo
22 4th gear input

[3XTurboAgain]

So i just have to repin everything and use parts of a 3.1 harness...sweet. its going to be reallll fun.

[merlot566jka]

fiero.nl 7730 ecm conversion, been there, got the dis to prove it. read about it there. darth ahs the charts and conversion tables on his website

[Joseph Upson]

So i just have to repin everything and use parts of a 3.1 harness...sweet. its going to be reallll fun.

This is the "bestest" forum for anything 60 degree V6 engine related, but what you are trying to do is a lot easier than what you think and has been detailed on the Fiero forum, you only need to relocate the pins to the proper terminals in the plug for use with the 730 ecm, the only plugs you'll need to change are those related to the sensors, in your case if you are using aluminum heads the 3.1 Beretta code will have you on your way in no time;

http://www.fiero.nl/forum/Forum2/HTML/079574.html

[3XTurboAgain]

Hey i havnt checked this thread in a while!! thanks a lot for showing me Darth Fiero layouts, i guess the Baretta code it is! Can anyone tell me what C203 is? Are they the connectors on the center console in my picture 2?? Thanks to everyone for all the help!