Reading through older threads doing research on a future swap for my 84SE. I know the 84s have their own added hurdles. Am thinking about an LA1 from a mini van because it has the highest hp/tq ratings and figure they will also be less abused. Also want the 4sp auto to go with the motor. If I get the harness from the donor for the motor/trans and the computer, beside replacing the fuel pump, would this be a relatively simple swap for a shade tree mechanic of years gone by. Will the stock intake for instance work in the Fiero? What about the axels? Mine already has an automatic in it.

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84Fiero SE 4 cylinder auto

there's more than one way to skin that cat,

obd1 '7730 PCM
-Done a bunch, relatively simple, old school, works
-becoming more difficult to find competent tuners to work with
-needs a trans controller
obd2
-also done, but not as much with a 3400, more frequently with a 3800.
-not as many tuning options
-works with the 4t60e/whatever the donor came with.
-will require HP tuners, or a DHP Powrtuner, which can be expensive, or hard to find.
Megasquirt/other standalone
-most tunable option
-most tuners will work with you on it
-less support on this forum, but has it's own dedicated forums.
-will require a controller for the transmission, could use a microsquirt.

Wiring diagrams are available here:

http://www.gmtuners.com/files/index.htm

Hardware:

The 3400 can accept modified stock V6 mounts, if you were to install it with a manual transmission, you could use stock trans mounts. being that you want to use the 4 spd auto that comes with the engine, you'll need to research mounts. My 3500 swap used a 5 speed, and I'm not as well versed on the automatics.


the alternator is going to be very close to the stock dogbone mount location and will probably require a decklid notch, you can use a stock 88 fiero timing cover/front engine accessory drive, but then you lose one of the crank position sensor mounts, and the OBD2 computer will no longer work.

I made my own low mount alternator, but something like it might not work with the automatic


I drew the top header flanges in this picture, because the other off the shelf options were trash



More details in the thread below, the file is available for download, and can be cut by a laser cutter like OSHcut relatively inexpensively for a well designed flange, they're best suited to a 1.5" OD tube swaged to fit inside the flange, or welding your desired pipe to the face of the flange. if you use them and like them, and want to buy me a beer for the effort I put in, my paypal info is on the drawing.

http://realfierotech.com/viewtopic.php?f=3&t=21666

https://drive.google.com/dr...YB3JtmcWl4JwRS4fHD6r

the stock intake will fit in the fiero no problem, but FYI, the can intake has a gnarly hump in it, which isn't very good for top end power. while you have the engine out of the car, it wouldn't be a bad idea to install new lower intake manifold gaskets, they have a tendency to fail and puke coolant everywhere, and will be easier to replace with the engine out, but not really hard to replace in the car either. if you do, the pushrods are two different lengths, the intake, short, the exhaust long, don't mix them up!

Hope this helps.

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"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."

cognita semper

OBD2 in general has been pretty scienced out by the 3800 community, as have the axle options.

I don't recall if the LA1 3400 has the 4T60E or 4T65E transmissions, but the axle options should be fairly well understood, although slightly different between the two.

The big packaging problem is the high mount alternator.
Those who have cut notches in the Fiero decklid structure have found that the decklid then bows and flexes at that point. The flex is noticeable with the decklid closed since the decklid springs are still pushing up on it.
Thus cutting a notch in the decklid is not adviseable and a low mount alternator is a better option.

Also, the Fiero does not use the hydraulic power steering pump, so the accessory drive has to be modified in some ways anyway.

quote Originally posted by Will: OBD2 in general has been pretty scienced out by the 3800 community, as have the axle options. I don't recall if the LA1 3400 has the 4T60E or 4T65E transmissions, but the axle options should be fairly well understood, although slightly different between the two.

this is true, it's also worth mentioning that the 3800 PCM's and 3400 PCM's have some interchange, and a 3400 can be run on a 3800 bin file, I personally have confirmed this.

quote Originally posted by Will: The big packaging problem is the high mount alternator. Those who have cut notches in the Fiero decklid structure have found that the decklid then bows and flexes at that point. The flex is noticeable with the decklid closed since the decklid springs are still pushing up on it. Thus cutting a notch in the decklid is not adviseable and a low mount alternator is a better option.

it's worth mentioning, many have installed the alternator in the stock AC compressor location with a bracket from another vehicle, I'm not sure what said bracket came from, maybe one of the guys who did it will chime in.

quote Originally posted by Will: Also, the Fiero does not use the hydraulic power steering pump, so the accessory drive has to be modified in some ways anyway.

kinda, LX9 3500's have an idler installed on a bolt on boss to replace the power steering pump. it's pretty straight forward. if you want to do it sloppy style, a 15mm hex head is a snug fit in most idler pulley bearings, a piece of M10x1.5 all thread, some washers, and 3 nuts, and you have an idler.

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"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."

cognita semper

[This message has been edited by ericjon262 (edited 01-08-2021).]

So the stock computer from one of these will not work, or will be much more complicated to install? 1996–2004 Oldsmobile Silhouette, 2001–2005 Pontiac Aztek,1999–2005 Pontiac Grand Am, 1999–2005 Pontiac Montana, 1996–1998 Pontiac Trans Sport

quote Originally posted by Rick6375: So the stock computer from one of these will not work, or will be much more complicated to install? 1996–2004 Oldsmobile Silhouette, 2001–2005 Pontiac Aztek,1999–2005 Pontiac Grand Am, 1999–2005 Pontiac Montana, 1996–1998 Pontiac Trans Sport

any of those should work, you will need a DHP powertuner, or HP tuners to adjust the calibration for VATs, among other things. I would recommend trying to get a '99 or later PCM, they support some of the better OSID's that are more tunable than the earlier PCM's.

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"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."

cognita semper

I'm looking to do the same thing. I have an '84 I'm putting a 3400LA1 minivan engine in. I can't find a V6 front bracket anywhere though.

keep your eye out in the mall, plenty of guys do swaps, and can't use their stock V6 mount anymore.

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"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."

cognita semper

I ended up making my own bracket for the front of the engine. There was also an issue with the Muncie clutch slave mount that didn’t work with the LA1 v6. I had to make a new one of those too.