Yeap, still here and continue to work on my 3.5 v6 swap.. R&D takes a lot of time especially when you are in unchartered territory.

As i had mentioned earlier, I was toying with the idea of doing mods to the transmission (4T45e) to fit my needs. I was not in the mood of getting another transmisson. I have already gone through three tranny's.

I have relocated the transmission connector location. The stock location of the transmission connector interferers with the exhaust manifold and exhaust crossover. I am now happy with the final results.

First things first: I removed the side transmission cover to access the transmission connector. I removed the transmission connector from the transmission and cut back the connector housing.


Photo of the connector housing cut back.


Photo of stock transmission connector housing with 36mm expansion plug installed.



I have my son fabricate a new transmission connector housing. Basically, just an Aluminuim block, 5/8" thick that has been machined.



Photo of the transmission side cover modified to accept the new transmission transmission connector block.


Photo of transmission side cover modified with transmission connector block in place.



Photo of transmission case (exterior) with transmission connector block installed.



Currently I am waiting on a number of items to complete the connector relocation. 1. RTV specific for auto transmissions. 2. A new transmission connector and wiring harness. Once those items arrive, I should be able ot complete the connector relocation and move on to the next item, axles!!!

I know such fun. Hopefully I have figured out what items I will need to complete the axle installation.

I'm having a couple of electrical issues with my swap!

Question, for you guys that have done a simular swap did any of you develop a wiring pin out or diagram of the wiring conversion? If you have would you be willing to share that information?

Thank you in advance.

Back at it....................

I have scrapped the 4T45E idea! I am just not comfortable with the exhaust crossover so close to the top of the transmission cover (actually touching it). I have ordered another 4T65E. Should be in a couple of weeks.

In the mean time I have shipped my ECM & TCM to Sinister Performance for some custom tuning.

Recently I have worked on the fuel delivery system. No my design, copying anothers idea.

I am back to building a wiring interface harness for the 3.5 V6 to Fiero swap.

Basically, I have started over with building a harness. I was having some issues so rather than continue troubleshooting I decided to start from scratch. One of the main drivers is because I want to minimize the number of wires that go from the 3.5 into the passenger cabin. Basically, the only wires going into the cabin with be the wiring needed for the drive by wire, minimal BCM wiring (that will be restricted to the OEM Fiero ECM location), etc.

Just about finished building the wiring harness for the 3.5 v6 swap! Only have a couple of wires left to identify. Needless to say, it has been eating my lunch. The reason being is that I wanted to minimize the number of wires for the 3.5 v6 enter the passenger compartment. In case, you don't know or I failed to mention, I am not using a traditional instrument cluster for the swap. I wanted to retain my current IC (Instrument cluster) which is a 93 Buick Riviera IC (digital). Which means I will be adding the OEM Fiero engine sensors to the swap; i.e. Oil Pressure, water temperature sensors, etc. For additional monitoring of the 3.5 v6 I will utilizing an Android Tablet connected to the BCM via a Bluetooth connection.

For power to the 3.5 I will be using the following:



This fuse block arrangement will be the power source for the 3.5

I have completed building the Fuse block for the 3.5 v6 Swap and tested it.

I have updated the photo of Fuse Block assembly. The Fuse block assembly is scheduled to be installed in the Fire wall OEM battery location area.

This a basically a bump...


Still working on the wiring interface, needless to say, having issues. May have to back track??

One of the big issues is sorting out getting the cruise control to function as designed.

Question for those who have done or in the process of doing a 3.5 v6 swap....... 2009-2011


Where are you getting your tach signal??

IIRC, the N* uses a similar coil mounting ( with 4 coils ).

The TACH signal may come from the ICM (high level signal) or it may come from the PCM (low level signal)
If it is a low level signal, you may need a Dakota Digital unit to feed your Tach.

i just read this all the way through.i had a g6 convertible with a 3.5.great engine.3.9 sounds even better.hopefully someone will come out with engine mounts and a wiring harness for it in a fiero.i can't even weld. i have an engine hoist from when engines came out the top.

[This message has been edited by richard in nc (edited 07-06-2024).]

I am or was in the process of getting the engine ready for a test start & run! The engine is not yet in the car but still on the test stand. I want to get everything squared away before installing the 3.5 in the GT.

While in the process of getting ready to put oil in the engine and a new oil filter I discovered that the oil filter does not fit. When attempting to install the oil filter the filter hits the cradle not allowing installation. So, back to the drawing board. What I wanted to do from the get-go was install a "remote oil filter kit".

I have ordered a Remote Oil Filter Mounting Kit from NAPA, P/N #ATP 18428. On their web site NAPA indicates they guarantee fit for a 2010 Chevy Impala 3.5 v6.


We shall see when the kit arrives.

Yeap, I am still at the install... as everyone can understand life has a way of interfering with projects. I hadn't realized how long it has been since I last posted on the project.

Some up dates:
1. The remote oil filter unit arrived and was installed (temporally for the moment - until the engine is in the car)
2. The 2010 3.5 v6 wiring harness has been sorted
3. The Fiero wiring harness has been modified for the conversion
4. In the process of rebuilding the new (to me) transmission (4T65e) Currently waiting on parts to arrive in order to complete the re-build
5. The 2010 3.5 v6 ECM & TCM has been reprogrammed by Sinister
6. Working on hijacking the 2010 Impala BCM to run cruise control and other support functions
7. In the process of removing the 2.8 v6 & 4T60 from the car for the conversion

Pending items:
1. The engine cradle for the conversion is being powder coated
2. Clean & paint engine bay on the existing engine has been removed
3. Build custom CV axles for the conversion - parts on order

[This message has been edited by Cajun (edited 05-07-2025).]

Having the engine cradle powder coated was a bad idea!! When attempting to re-install the engine/transmission the cradle got all chipped up. Back to the drawing board, had the cradle sand blasted and painted.

That way any scratches, bruises etc. can be easily repaired with a little paint touch up.

I am confident now that I have high jacked the BCM? [plan is to have cruise control with this swap} I am just about completed the wiring for that puppy.

This is basically a test run of the "Upload Media" function. I was having issues with PIP and asked the question on the General Discussion section regarding my PIP issues. A couple of members stepped up and responded to my question. Thanks guys....

The weather here in South Louisiana has not been cooperative of late! Rain for the better part of two weeks now and more to follow in the coming days.

I have managed to get a little work done on my engine swap.




With regards to hi jacking the BCM, I have fabricated two circuits to trick the BCM into thinking that I am using the ignition switch from a 2010 Impala. Another circuit to allow me to utilize the Fiero cruise control stalk with the 2010 Impala cruise control system. This circuit is basically the resistive ladder in the steering wheel on the Impala




The circuit on the left is the ignition switch; the one on the right is the cruise control resistive ladder.

[This message has been edited by Cajun (edited 06-15-2025).]

The engine is out at last.....



Once my son completes fabricating the rear transmission mounting bracket, I will be able to secure the engine to the cradle. Once I get that mounting bracket I will post photos of both transmission mounting brackets, front & rear.

I have upgraded my fuse block for the swap. I needed additional fuses (BCM).

At long last the 3.5/4T65e are attached to the engine cradle.



The front transmission mount if a modified Fiero transmission mount bracket.


The rear transmission mount is all fabricated by TwistedViz Designs (my son's company).

Here is a photo of the circuit I am using to trick the BCM (Body Control Module) into thinking I'm using the ingnition switch from a 2010 Impala.

The remote oil filter assembly has been installed:



Currently I am waiting on parts. I.e. CV Axles, Coilover springs & sleeves, and other bits and pieces.

Also working on cleaning up the engine bay to receive the new engine/transmission.

The high torque starter has arrived and installed.



I have pretty much decided to completely overhaul the rear suspension on the GT. I have ordered a pair of rear wheel hub & bearings, Poly Cradle mounts & bushings (they have arrived), a pair of rear struts, a set of 12"-300# coil over springs, and sleeves to match. Now, waiting on parts.

The wiring harnesses for the swap is pretty much complete. The balance will or has to be done after the engine/transmission is has been installed in the GT.

While waiting on parts I decided to do some housekeeping:

Removed the rear brake system from the GT to clean up, paint and re-install on the 3.5 cradle
Relocated the Charcoal canister

Finally got around to removing the springs from the rear strut towers! Wow, both struts were totally gone. Replacement are on order.

Fitted the coolant tube from the passenger side.....



Man, surprising how much bad stuff one discovers when they begin taking the vehicle apart. For starters:
1. Driver side front caliber leaking
2. Bad struts
3. crushed driver coolant tube (the car has never overheated on me - that was a total surprise)

I have cancelled my order for coil over kit (parts). Mainly because I'm not sure of the new struts that I have ordered. Once they arrive and can determine their diameter I plan on reordering the coil over kit.

Waiting on the following parts:
1. pair of rear wheel hubs & bearings
2. Rear struts
3. CV Axle for the passenger side


I know that I have posted a large amount of photos. I am doing so to help folks out there with their future build.

Currently in the process of removing the dash and center console. This operation is necessary in order to remove some previously added wiring that is no longer required, remove the accelerator cable and pedal (no longer needed - drive by wire) and to add wiring needed for the engine/transmission swap.




At this juncture in time it doesn't look like I will be making Fierorama this year as a couple of suppliers have informed me that a couple of parts I have ordered are on back order. The delivery dates are estimated to be 3 to 4 weeks. That sucks....

I have completed removing the dash and center console.

Removed the accelerator pedal and in the process of removing the accelerator cable assembly.

Dash & center console removed - Driver side view


Dash & center console removed - Passenger side view


Need to make a run to Stine's to pickup some bolts to mount the 2010 Impala accelerator.