Engine Swap

[Kdon]

I recently bought a 1994 Oldsmobile cutlass supreme convertible from the auction. Who ever had it started a engine swap on it with a supercharged 3.8, should I snatched everything out and get another 3.4 or try to see if I can get the 3.8 running?

Edited April 12, 2022 by Kdon

[94 olds vert]

I know the car you are talking about. I saw it come up for sale on auction. The 3.8l in there is a good engine swap choice. I bet who ever was putting it in ran into issues with the OBD II into an earlier car. 

There are threads around here that talk about that issues. 

[rich_e777]

Post some pics!

An abandoned project car with an engine swap sounds about as fun as grabbing a wasp nest bare handed. Ive always wondered what happened to all the cars with the l67 swaps over the years. 

What all is there and can you tell how far along the swap is? Theres a few useful swap threads that I`ll try and dig up when I have some more time.

[Kdon]

Ok appreciate it

[Kdon]

[pwmin]

Sweet.  Yep, looks like they gave up on their hack wiring.

[Bake82]

You bought this complete?  
it looks like it’s got a few of performance parts on it!!  
 

intercooler, fuel rails, northstar with an lq4 TB who knows what else!! 

 

If it’s just a wiring issue, find a 98-99 Monte Carlo z34 or lumina LTZ woth a 3.8, get the engine harness off it.  With a few minor changes to the c100 firewall plug and 2 wires run inside for the obd2 port, and a PCM tune it’ll run no problem!  
 

 

[94 olds vert]

With an inercooler and a N* TB you could drop the pulley size. 

[Kdon]

Do you have any pics of it ?

[Bake82]

2 hours ago, Kdon said:

Do you have any pics of it ?

Pics of what?

[Bake82]

3 hours ago, 94 olds vert said:

With an inercooler and a N* TB you could drop the pulley size. 

Agreed.  But he needs to get it running first before anymore mods!

[Kdon]

3 hours ago, Bake82 said:

You bought this complete?  
it looks like it’s got a few of performance parts on it!!  
 

intercooler, fuel rails, northstar with an lq4 TB who knows what else!! 

 

If it’s just a wiring issue, find a 98-99 Monte Carlo z34 or lumina LTZ woth a 3.8, get the engine harness off it.  With a few minor changes to the c100 firewall plug and 2 wires run inside for the obd2 port, and a PCM tune it’ll run no problem!  
 

 

I bought it from a auction this way I believe the engine came out of a Pontiac Grand Prix. 

[94 olds vert]

7 hours ago, Bake82 said:

Agreed.  But he needs to get it running first before anymore mods!

Yes. Always maintenance before mods. Scan for KR along the way. 

Edited April 16, 2022 by 94 olds vert

[Bake82]

7 hours ago, Kdon said:

I bought it from a auction this way I believe the engine came out of a Pontiac Grand Prix. 

Understood.   
 

to get this running you’ll want the Monte Carlo/lumina harness or get a new GTP harness

 

you'll also need GM service manuals from the 1994 cutlass supreme and either the Monte Carlo or the same year Grand Prix gtp you pull the harness from in order to figure out the wiring at the c100 you need to do.  
 

once you get it running you’ll need to get the PCM tuned because of the northstar throttle body and lq4 MAF.  
 

 

if you decide to swap back to a 3.4 you’ll need the 3.4 and trans and a 1994 cutlass supreme wiring harness.  
 

If you went to a 3.4 I’m guessing you could sell all the 3.8 performance pets for the cost of the other motor.   

i have a 3.8SC in my 88 cutlass.  I’d try everything to get it running.  It may be more work because of the unknowns on the swap but if you take you’re time to go through the wiring and the rest of the swap I think it’s way better option than the original motor.  

Edited April 16, 2022 by Bake82

[Kdon]

Ok appreciate it

[Bake82]

Good luck!    The harness may be a bit tricky to track down, but I do recall someone selling one on one of the3800 Facebook groups.  Try 3800 Marketplace.    
 

once you have that and the manuals,  it’s really just some time and reading the manuals to sort through the wiring differences.  
 

I was thinking about the PCM, you are going to need a PCM tune first because of the lq4 MAF you have.   Again on the 3800 Facebook groups  I would find “Daniel Smuts”.  He offers remote tuning and would be the most cost effective I think.  
 

 

other than the wiring, is everything else done?  Axles, exhaust downpipe, heater coolant hoses, power steering lines?