On my first swap requiring rewiring I used the harness from the donor vehicle. It was a mess and needed to be redone after a computer got fried for some reason. With the 3500 swap I'm doing I first soldered the wires from the ECMs plugs to the ECM side of the Fiero harness, which you don't have to do if the pins can be removed and inserted in the plugs of the replacement ECM, next I'll solder in the sensors on the engine side of the harness since I'm using the wire from the newer engine. I started with the first plug and just went down the pin assignments skipping the ones that would not be used like the ones for an automatic transmission or extra fan etc. After it's all done I'll check the engine side of the harness against the ECM side with a multimeter.
I labeled the wires from the ECM first, then removed them from the harness plug one at a time, slipped a piece of shrink rap over them and soldered. Next is to set heat wrap and tape the wires up in a bundle so it looks neat.
Yes you are making it more difficult the only connection point to the Fiero is the C500 and C203 what ever dose not go there is extra which unless it is ignition power you most likely do not need. Look at the pin out for each of the Fiero connectors and find which wire from the 3100 matches. An example the service engine soon light, the wire is brown with white and enters the Fiero through C203 pin C take the wire from the 3100 computer which is either labeled as SES or MIL control and route this wire so it will reach the C203 connector and solder it in place. Another TCC for the tranny lock up converter it exits the Fiero through C203 pin P it is a purple wire. Take the wire from the 3100 computer labeled for TCC and route it to reach the C203 pin P and solder it on. Continue with this till all wires for the two Fiero connectors are finished. Remove the rest of the wiring for things like ABS or traction control the things your Fiero doesn't use. Only confusing part is where to get the extra sources for ignition power as the newer engines have more things requiring power. Feed all the ignition wires that didn't get connected to the C203 and C500 and feed them to the fuse panel and use in line fuses. In line fuses can be purchased at many places ,get the ones that use the same type fuses the Fiero uses. Dan
Thanks for the support Getting all the papers togeather to start matching up .l was looking at the 3100 wiring it has alots of power points look likes i can get by with out some
I'm reading through this thread, and I'm a little confused on a couple points. (Bear with me, I only started researching this swap a couple days ago.)
I might have missed it, but it looks like you're retaining the Fiero ECM with this swap. I didn't think the Fiero ECM was programmed in such a way that it could control the nicer benefits of this engine, like sequential injection and DIS ignition.
If you are using the 3100 computer, I'm still confused. I'm under the impression that the 3100 was OBD1 up through 95, and then in 96 they switched to an OBD2 system. Please correct me if I’m wrong. For some reason just wiring it up through the C203 and C500 connectors just like the stock motor seems too simple. Doesn't OBD2 require different sensors and more of them that have to be wired to the ECM?
What about the transmission too? Is it pretty painless to upgrade to the 4 speed auto while you're at it, or is it a lot easier to just stay with the stock 3 speed? If I go ahead with it, I'd like to upgrade the tranny but I'd be working with a tight budget and a mild time constraint. (It's not that it's my daily driver or anything, but the car has been sitting around my friend’s farm with a blown engine for long enough. I'd like to get it out of there before it assimilates with the broken Camaros.)
The Fiero ECM along with its wiring is tossed other than a bit left to work with from the C203 and C500. The 3100 harness just like a 3800SC harness is basically a stand alone system. With its own PCM all that is needed is to supply power and grounds where needed and to feed gauges for us to read. These connections are made through the two main Fiero connectors which feeds every thing needed except a few extra sources of power which the newer systems use. All the 3100 sensors are used in the swap so when finished the engine is being fed every thing just like it was in the donor vehicle. Only thing needed after that is one simple circuit to make the Fiero speedo operate off the 3100's 4speed auto's signal. Dan
Awesome, just came across this thread and it answered (or poses?) a question for me! LOL Some math: If engine A (3100) fits into a Fiero, and engine B (3800SC) fits into a Fiero, will engine B (3800SC) fit into car that engine A (3100) came from? LOL In other words, since the 3800 fits into the Fiero, and the 3100 fits into the Fiero, will the 3800 fit into my Malibu that has a 3100? Would make a fun sleeper. Some how I think I'd have to cut a hole in the hood for the blower. Is it bad that I'm thinking of modifying my Malibu with the engine from my Fiero?! Nah, I wouldn't do that. Seeing you guys actually work on your cars makes me jealous though, wish I had the time to finish my poor sad Fiero. Good luck with the swap, it's good to see someone not afraid to dig into the heart transplant operation. Edit.. Should I mention that I have to replace the stock automatic attached to my 3100 tomorrow? It's about completely blown. (4T40E) Also the lower intake gasket is "the worst lower gasket leak I've seen on one of these engines" according to the GM service guy that looked at it... They want $950 to change that gasket... That said, it has moved the Malibu around pretty quickly and should do well in the Fiero. That stock computer does top out at 105mph though.... ------------------ Bob Williams Working on the next 3800 swap.. Missing the one that worked!
[This message has been edited by Riceburner98 (edited 11-17-2006).]
Awesome, just came across this thread and it answered (or poses?) a question for me! LOL Some math: If engine A (3100) fits into a Fiero, and engine B (3800SC) fits into a Fiero, will engine B (3800SC) fit into car that engine A (3100) came from? LOL In other words, since the 3800 fits into the Fiero, and the 3100 fits into the Fiero, will the 3800 fit into my Malibu that has a 3100? Would make a fun sleeper. Some how I think I'd have to cut a hole in the hood for the blower. Is it bad that I'm thinking of modifying my Malibu with the engine from my Fiero?! Nah, I wouldn't do that. Seeing you guys actually work on your cars makes me jealous though, wish I had the time to finish my poor sad Fiero. Good luck with the swap, it's good to see someone not afraid to dig into the heart transplant operation. Edit.. Should I mention that I have to replace the stock automatic attached to my 3100 tomorrow? It's about completely blown. (4T40E) Also the lower intake gasket is "the worst lower gasket leak I've seen on one of these engines" according to the GM service guy that looked at it... They want $950 to change that gasket... That said, it has moved the Malibu around pretty quickly and should do well in the Fiero. That stock computer does top out at 105mph though....
When you tell it like than that is what i had in mind when l started this swap that is all l would have to do sorting wires first thing sat the colored wires should match the paper i have right??? let you now more later thanks Gary
The 3800SC will fit in any FWD GM vehicle that had a V6 as an option quite easily, have put them in Cavaliers (older style), Pontiac 6000's and even my 95 Trans Sport van has a series II 3800SC in it. Just like the Fiero the wiring is the biggest part of the swap. Dan
Can i use the fule pump from the 3100 and will it fit Droping the gas tank next help???
It will probably fit without effort depending on what the fuel system is like. I don't know what year but GM switched to a fuel pump "portfolio" system where everything comes together as a unit, fuel pump and fuel level assembly. I have one from an 8100 V8 and it took a good bit of effort to remove the pump from the assmbly. It's a little different but can be made to work and by the weight of it appears to have been built to meet the demands of the higher pressure it supports.
Personally I would not use a used fuel pump unless I knew for sure it was very low mileage, because it's not something you can fix easily on the side of the road should you find yourself there.
just put in new pump the longer i looked at it was better to just get new pump What kind of fuel lines will i have to put on will stock work pump puts out 95 pd welcom all help
I always replace the fuel lines on swaps with new metal and the rubber upgraded to 100PSI lines and only use the proper fuel injection line clamps. Don't trust those old hose clamps for the pressure or atleast not with 3800SC's. Dan
Do you start with lines from gas tank or do you put new rubber line there then go metal then back to rubber to the engine l was going to use the line clips that snaped on to the throtle body that is metal and rubber toghter then metal then rubber to the tank ???? is will rubber lines work at the tank and just clamps????
You have to reuse the metal lines across the top of the tank I replace every thing from that point on and those metal quick disconnects on the engine can be reused just clamp rubber hose onto them. I also move the fuel filter up to the location used in the 84's that way it is accessible and doesn't rust away. Dan
AC lines is there an easy fix a shop will make lines from the 3100 ac to the fiero lines 85$ does this a good price??????? Then that kind of freon to put in??????
A set of aluminum head adapter plates come in pretty handy :
They adapt the aluminum head pattern to the fiero accessory brackets. Not that hard to make, or at least I did not think so. They allow you to use the entire front cover, water pump, altenator, etc from the Fiero 2.8, which is what I did for the 5-spd turbocharged 3100 swap into my Formula project.
That is a Moroso inline coolant filler (Jeg's part# 710-63745) with a slightly modified 1988 4CYL rear upper outlet hose. Here is a close up of the coolant fill system:
It uses a ported/clipped mitsubishi TD05 Big16G that attaches directly to the rear manifold. The exhaust system is 2.5" mandrel that redirects forward to use the stock routing, even uses the stock muffler location. All custom tuned (by me) to deliver around 320 hp at 14 psig. The motor was a brand new crate 3100, rebuilt with custom Ross forged pistons, Total Seal Extreme rings, ported polished heads, etc. It uses a 1227727 OBD-I PCM with modified turbo grand prix code. Has an artificial intelligence controlled onboard vehicle network which automatically performance optimizes the tuning, wide band oxygen sensor, indash motorized 7" Touchscreen LCD. Pwr locks, mirrors, and windows are all controlable from the touch screen, a cell phone, a pocket PC, or voice command. It also has a GPS navigation system, a 40 Gb hard drive full of mp3's, and onboard EV-DO internet access served out over its mobile WiFi access point. The smart move is to stop now, before a simple hobby transforms itself into a monster that consumes all available time and energy like mine has. ------------------
[This message has been edited by Mick (edited 11-22-2006).]
can not seem to get the wiring wright as you can see from the pic having truble the c203 dose not have this many wires from it and all the paper work i got from Dan helped some my 96 3100 swap has a lot of wire i know i do not need when i try to go to the c203 no start no fire But when the wire is back like this it will start and run
So can some one tell me where i went worng all HELP needed
I always cut the extra plugs right off so I can easily remove any unwanted wires and it is a lot easier to route the wires where they need to go when you deal with one wire at a time. Also if you look at the diagrams it should show what fuses the 3100 used then gang together all the wires that went to each fuse in the 3100 and run them to a fuse in the Fiero. Still use the same source for things like the ign module gets its power through C500 E3 so connect pink wire from ign module to this point. Injectors got their power through C203 J and K but since the 3100 is a sequential injection engine it only needs one fuse for injectors so use C203 pin J for injectors and use a larger fuse. Now C203 pin K is available for feeding ignition power to one group from the 3100. Still use the C203 as power and feed for the fuel pump relay. C203 pin F is still ign feed for the PCM and so on. Like I have said many times remove those nasty 3100 firewall connectors and run one wire at a time, make the harness neat and clean and solder then heat shrink all connections. Follow this take your time and every thing will work out fine, wiring is something that can not be rushed. Dan
CAN some one tell me if i need both of coolent lines the one ine front back to the throttlebody then back around to the front line in the back goes back to the thermostat housing i only have line to put it on it came off the under side manafold 4cyl can i put them on a tee or where?????
help i have some pic of the 3100 pin outs can you tell me if the ones i have marked is the one l need to hook to the c203 pluge and if so in what pluge order you can see what i have
this is not all of the pin out l can post the rest if it will help please post if im going in the right was thanks
CAN some one tell me if i need both of coolent lines the one ine front back to the throttlebody then back around to the front line in the back goes back to the thermostat housing i only have line to put it on it came off the under side manafold 4cyl can i put them on a tee or where?????
Cant help much with that as one of the advantages I obtained by using the Fiero 2.8 water pump and front cover is that you can do away with most of the 3100 coolant plumbing. I threaded that large hole in the intake where the coolant line attaches and put a fan temp switch there. The function for most of the 3100 coolant line mess is really nothing more than a stupid throttle body heater, but it also functions as the bypass when you are not using the Fiero 2.8 front cover and pump. As far as the wiring goes, Im really not sure why anyone would want to use an OBDII PCM unless they were using the newer electronic auto trans and needed to control it. I do mine with the engine wiring harness removed, easier to accomplish that way for me is all, as my health does not permit bending over an engine bay for hours on end anymore. It also makes it much easier to clean up the harness and replace all that old cracking plastic wire loom with new stuff. Why is that plastic wire loom so dam expensive anyway? The cost seems to go up exponentially with diameter.
Whenever I create a soldered connection underhood, I seal the exposed solder and wire with acetic free silicon sealant and then top it off with a heat shrink tube while its still a bit tacky. If you do it right, the seal is just as good as an undisturbed wire.
[This message has been edited by Mick (edited 11-26-2006).]
C203 B-this comes from the fuel pump fuse feed it out to your fuel pump relay C-SES light or mil light from the mil o/p on the PCM D-A/C relay control this is 12 volts from the pressure sensor feed it to your A/C clutch relay E-oil pressure signal from sending unit to gauge F-ECM ignition power feed to the PCM ign G-speedo see note at bottom H- no longer used
J-inj fuse feed already discussed K-inj fuse aslo already discussed L- fuel pump feed this is from your fuel pump relay and feeds the fuel pump M-ground just run a chassis ground to this pin N-A/C feed this is 12 volts for going through clutch relay to run compressor P-TCC this comes from brake pedal connect to PCM TCC i/p R-speedo see note below
Speed sensor yellow and purple feed directly to the PCM only. Take the speedo o/p from the PCM and feed it to C203 pin G. take the purple wire from C203 pin R and connect it to chassis ground. At the speedo remove the lower plug and instal the buffer circuit here using the yellow from C203 as feed from PCM. This is one of those things I have done many times but is hard to describe so does this make any sense. Dan
Yes it is starting to look like im geting some where , some more ?? my oil sending unit has 3 wires from it 2 of them will let the fuel pump start will i just use the center wire ??? what adout the tack on the c500 c3 white tach 3100 pin 9 white there is no wire from that pinout do i add it or wire some place else ??/ THANKS
The feed to work the Fiero tach comes from the 3100 ignition module not the PCM the Fiero tach will not run off the signal from the PCM. With three pin oil pressure sensors two are a switch and the third works the gauge. Dan
Would make a fun sleeper. Some how I think I'd have to cut a hole in the hood for the blower. Is it bad that I'm thinking of modifying my Malibu with the engine from my Fiero?! Nah, I wouldn't do that. Seeing you guys actually work on your cars makes me jealous though, wish I had the time to finish my poor sad Fiero. Good luck with the swap, it's good to see someone not afraid to dig into the heart transplant operation. Edit.. Should I mention that I have to replace the stock automatic attached to my 3100 tomorrow? It's about completely blown. (4T40E) Also the lower intake gasket is "the worst lower gasket leak I've seen on one of these engines" according to the GM service guy that looked at it... They want $950 to change that gasket... That said, it has moved the Malibu around pretty quickly and should do well in the Fiero. That stock computer does top out at 105mph though.... 
