The car: 86 Fiero 2m4 automatic. The plan: depose the Duke and install a 3400sfi/4t65e. The reason: cheap way to double horsepower and gain overdrive.
What I've got: 1) 105 mile 3400sfi and 4t65e from a 2005 Impala ($250) 2) bits of the 3400 wire harness (just the connectors for all of the sensors with about 12" of wire still attached) 3) 2005 Impala ECM and connectors with about 4" of wires
What I'm missing: 1) starter 2) wire harness between ECM connectors and sensors 3) axles 4) air intake
What I've done so far: (Aside from hours of reading and printing info). So far, I've inspected the 3400 and haven't found any obvious oil leaks or missing sensors. I removed the alternator from it's stock location and started making a bracket to relocate it to the lower, opposite side of the engine. Before doing anything else, however, I want to start working on putting a wiring harness together.
Good luck on the swap. One of the guys in our club has the 3400 swap and he loves it. He did say the wiring was a bit tricky though.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Mounting the alternator was surprisingly simple- two of the bolt holes on the side of the 3400 block for the AC bracket line up perfectly with the mounting bolts on the alternator. They even position the alternator so that the pulley is in the correct plane with the rest of the belt pulleys. All that is needed is a small bracket to space the alternator away from the block, and another small bracket to connect the lower alternator bolt to the block. Here is my crude attempt at the upper bracket using a scrap that I found in my misc steel pile and two 10x1.5 flange nuts. Please disregard the nasty appearance of my welds. [img][/img] I see a couple of options for the lower mount- there is an 11mm threaded hole on the front of the block close to the alternator mount so I'll probably just make something to connect the dots. [img][/img]
I like to keep things simple and with the tensioner in its stock location, what do you guys think about this for the belt routing: [img][/img]
Maybe I could incorporate a small idler pulley onto my lower alternator mounting bracket to give the belt a little more purchase on the alternator pulley. [img][/img]
EDIT: must have been asleep when I did this- aside from the fact that the water pump pulley is for the outside of the belt, my routing will spin it backwards. I see now that there must have been a power steering pump or idler pulley above and to the left of the water pump that I'll have to recreate.
[This message has been edited by Yorgle (edited 09-12-2024).]
Good luck on the swap. One of the guys in our club has the 3400 swap and he loves it. He did say the wiring was a bit tricky though.
I think the wiring will be tedious, but not particularly difficult as I will be using the donor Impala ECM, which I plan to mount in the trunk. The stock Fiero ECM can just continue living a useless life inside the console. I'll have to construct a mini-harness to run the VSS, tach, temperature and oil pressure gauge wires forward, or maybe I can just pull them from the existing Duke harness.
I like to keep things simple and with the tensioner in its stock location, what do you guys think about this for the belt routing: [img][/img]
Maybe I could incorporate a small idler pulley onto my lower alternator mounting bracket to give the belt a little more purchase on the alternator pulley. [img][/img]
EDIT: must have been asleep when I did this- aside from the fact that the water pump pulley is for the outside of the belt, my routing will spin it backwards. I see now that there must have been a power steering pump or idler pulley above and to the left of the water pump that I'll have to recreate.
try like this.
LX9 3500's have a bolt on idler in the location of the star in applications that use electric power steering. I assume you aren't going to use AC?
Most of the connectors and their terminals are available from Ballenger Motorsports, they offer "connector kits" that I found to be the most reasonably priced when considering the convenience of buying them one at a time and not by the thousand.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.
I mounted an idler pulley as suggested and found a 49" belt that fits. Thanks for the tip. I then changed out intake gaskets and shot some maroon paint on things to pretty it up. Oh, I also swapped the valve covers around so the oil filler will be easier to reach. [img][/img]
Now it's time to focus on the PCM and getting a harness wired up. My goal is to get the 3400 as close to *ready-to-run" before I drop the Duke from the car. It seems from what I've found in other threads here and on the 60degV6 forum that using the stock 2005 Impala PCM is not a good idea, but I'm not sure why that would be- after all, it ran things just fine in the Impala. I'm guessing there must be some security feature that is problematic. If anyone here has done this swap, I'd love to hear what you did for a PCM.
I'd love to know how you like the performance / behavior of the engine once installed. I loved the 3400 motor in the Grand Ams... and think it should be awesome in the Fiero. It's such a smooth running engine!
I personally prefer standalone aftermarket ECU's, but a 3400 can be run off a bunch of different PCM's, and even a '7730 OBD1 ecu. I ran my 3500 with a 3400 PCM before I went megasquirt, it worked, but it was a bit more difficult to tune, and required OBD2 tuning software, which can get expensive. being that you want to run the transmission too though, using the stock Impala PCM is probably a good idea, it will need VAT's turned off, and a few other flags adjusted, but then should run ok with only minor tweaks.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.
I personally prefer standalone aftermarket ECU's, but a 3400 can be run off a bunch of different PCM's, and even a '7730 OBD1 ecu. I ran my 3500 with a 3400 PCM before I went megasquirt, it worked, but it was a bit more difficult to tune, and required OBD2 tuning software, which can get expensive. being that you want to run the transmission too though, using the stock Impala PCM is probably a good idea, it will need VAT's turned off, and a few other flags adjusted, but then should run ok with only minor tweaks.
Since I'm leaving the 3400 stock, I'd like to use the Impala PCM if possible. Can you recommend someone who can do the programming tweaks you mentioned?
I'm sure Ben at WOT-Tech, should be able to get you what you need, now you'll just need to wire everything up according to the PCM/engine/trans combo you have, it's not too bad.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.
[This message has been edited by ericjon262 (edited 09-21-2024).]
I'm sure Ben at WOT-Tech, should be able to get you what you need, now you'll just need to wire everything up according to the PCM/engine/trans combo you have, it's not too bad.
That's exactly what I did. My freshly programmed PCM just arrived and now I'm in the thick of building a wiring harness from scratch. I realize I could have gotten a 3400 harness from the boneyard and just modified that, but I like the idea of wiring it completely from nothing as it forces me to learn every component. Plus it gives me the opportunity to route the wires where I want them. Ben provided me a very clear pinout of the PCM connections which makes things a lot easier.
Nice work and looking good. The only item that I would suggest adding is the A/C compressor. On those 90* days you'll appreciate having it. Its not a real hard job.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
My passenger-side axle for the arrived from NAPA today- GM-8063, which according to what I've been able to find, should work for my swap. I took off the retaining clip to test fit it into the 4T65e (didn't want to risk getting it stuck in there). The diameter and splines fit perfectly, but I'm wondering about the gap between the seal and the edge of the tulip- does that look excessive? For what it's worth, the stock passenger axle on the TH125 in my '86 has about the same amount of gap.
Of course, I won't know if the overall length of the axle is correct until I actually swap in the new motor/transmission. Meanwhile still working on the wiring harness.... so many many wires...
My son and I have finally started in earnest on the actual swap. Rather than set the cradle down onto a cart, I figured, why not make the cradle itself into a cart, which significantly reduced how high we needed to lift the car.
I just used chair casters from my junk pile but so far they are holding up quite well.
I posted it for as a free engine on Facebook Marketplace and within minutes had several takers. By evening, it was pulled from its cradle and loaded onto a guy's trailer to go live in someone else's garage.
[This message has been edited by Yorgle (edited 06-03-2025).]
I made a quick and dirty transaxle mount bracket so as to re-use the existing mount on the driver side. Eventually, I'll make a nicer, heavier version. On the other side, I was able to re-use the top bracket from the 3400 engine and the existing Duke motor mount - just had to drill new holes to move everything back about 1.75" to clear back part of the cradle. Even so, there were still a few points of interference- part of the cradle needed to be notched a bit to accommodate the transaxle servo and pan flange. I'll also have to notch the tie rod link mount on the driver side to clear the flange on the transaxle. I also have figure out how to modify the connector for the VSS because it hits the tie rod link mount on that side.
[This message has been edited by Yorgle (edited 06-05-2025).]
Here she is resting happily in her new home. Just for kicks, I set the dog bone into its bracket and was surprised to see that it lines up nearly perfectly with the lift bracket on the 3400 so I think I will just use that as the basis for a new mount.
Slow but steady progress. I had to reposition the motor mount about an 1.5" further toward the front of the car to get the engine sitting perpendicular to the centerline of the vehicle. I'm not happy with where this puts the mount in relation to the bracket on the cradle, but it's secure enough to continue with the swap. After the bugs are worked out, I'll fabricate a custom bracket for that side.
One question if anyone can help: I'm using the 2005 Impala alternator, which in addition to the large red battery cable, has two smaller wires coming out of the connector- one identified in the schematic as "Generator Turn On Signal" and another called "Battery Positive Voltage". In the Impala schematics, the former connects to the PCM and the latter to the power junction block. The Fiero alternator harness also has the large battery cable along with two smaller wires- a thicker red wire and a thinner brown wire. I presume the red wire would connect to the "Battery Positive Voltage" wire on the new alternator, but is the brown wire the equivalent the "Turn on Signal"?
Since I'm leaving the 3400 stock, I'd like to use the Impala PCM if possible. Can you recommend someone who can do the programming tweaks you mentioned?
I know you're already well on your way, but I wanted to comment on this. I recommend sticking with a factory ECM / system... as opposed to an aftermarket one. Normally I'm all about aftermarket systems, but one of the real benefits of the 3400 SFI is the three letters at the end, sequential-port fuel injection. MOST aftermarket systems don't support SFI... just MPFI. You probably already know the difference, and it seems you've already decided to keep the GM ECM as I see... but for those who don't know, SFI squirts fuel (just before) only to the valve that's getting ready to open, rather than MPFI systems that squirt fuel on the left side, then on the right side in banks. At wide open throttle... there is ZERO difference in performance. But in around-town driving, SFI provides better fuel economy, smoother idle, and more horsepower / better performance up through 3,000 rpms. So totally worth it.
Not sure how you solved the wiring issue... but if it were me, I'd be trying to find a factory harness online somewhere.
When my daughter rebuilt her engine, we took the factory harness and completely opened it up... which you'll want to do with an aftermarket harness.
One of the things to consider is that in GM vehicles of this era... the ECM is totally independent from the gauges, which is really nice. So, you can keep a stock set of gauges, and you just need to run the factory harness to the sensors. I recommend opening up your factory 2.5 Iron Duke harness, and removing anything that has to do with the ECM, but keeping everything that goes to the gauges... like the temperature sending unit, the tach filter line, oil pressure sending unit, etc. But another thing you'll probably want to do... is re-route some of the wiring around the engine. No point in keeping the factory location when you're putting it in a different engine bay. It might make more sense to move a few things around.
Also... last bit of advice if it matters... try to get absolutely as much done as you can with the engine out of the car... once it's in the car, it becomes a pain in the ass.
Looking forward to seeing how you like it when it's done.
EDIT: Looks like it's already in the car... haha... I posted too late. But glad you kept the factory SFI ECM.
[This message has been edited by 82-T/A [At Work] (edited 06-13-2025).]
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