FAQ: Series I to Series II / Series III Engine Swap

my 97 riviera has a complete harnes and PCM.... could it really be drop in hook up and go?

87TurboRiviera wrote:

my 97 riviera has a complete harnes and PCM.... could it really be drop in hook up and go?

It would be best to wait and hear from someone that has already done one or two.
I'm not sure if the 97 motor has to be wired like the 95 or whether you can use the 97 harness and 97 PCM.?????
The more I think about it, the more I'm not sure.

Derek (deekster_caddy) might know from experience. If he doesn't he knows someone that does.

wait 95 rivieras ae OBDI arent they,,,,

The 95 car has an OBD2 port under the dash, but the PCM is OBD 1.5
It's an oddball year. The programming is somewhere in between 1 and 2
That's why I'm not sure which direction you have to go.
Do you have to stay with the 95 wiring and PCM or is it possible to "upgrade" to OBD2 with the 97 wiring and PCM and some additional wiring.???
I don't know the answers to these questions.

Something else that needs to be considered is the Transmission programming.
The 97 is full electronic and the 95 has a vacuum modulator.
Yet, another issue that has me thinking you will have to stay with the 95 wiring and PCM.
But again, I would rather someone that has more experience speak to these issues.

but if im swapping out all the wiring, the tranny, and the egine and PCM,, i would think it would work, anything else is just wiring up the speedometer and tach..... not big projects....

I didn't know you were swapping tranny's also.
There will be the need to run additional wires to the ALDL connector under the dash from the PCM if your going to OBD2.
That's where the wiring diagrams will be necessary.
I'll bet Billboost has done one before. If Derek doesn't know first hand he has contact info for Bill.

those wires run from the PCM to the wirewall connector to the OBS port under dash right?

87TurboRiviera wrote:

those wires run from the PCM to the wirewall connector to the OBS port under dash right?

I don't know if all of them do, that's why I would want a complete wiring diagram.

wow i cant type... the wirewall? lol i feel dumb

I'm not positive about the motor mounts.

Here's an important question I haven't seen answered yet - are either of these Riv's supercharged? '95s have the Series I 3800 if supercharged. '95s have the Series II 3800 if N/A. '97 would be series II either way. It makes a big difference how the project will go.

I recommend taking the '97s complete drivetrain though, the trannies are a little improved over what the '95s have. But you will need the PCM and complete wiring harness to make the swap as painless as can be.

I'm not sure how different the engine/trans mounts are. I have little firsthand experience with '95s except answering questions like these

i know the 95 and 95 tranny mount is interchangeable.. same part number at autozone

Ask Corey, I think he put a SII into his '95.

87TurboRiviera wrote:

Just bought a 95 riviera and a 97 riviera engine.... was wondering what all i will need to mod to drop it into this car.

This was your first post.
It's a bit confusing now because you start off saying you need to replace the engine and you have already bought one, now you say all you need is a transmission and radiator.?????

And another post you inferred you had a whole 97 car to take parts from. Very confusing.???

yeah... the trans is toast.. im wondiering how easy it would to just flop in a whole Series 2 motor into it... I gotta frop the motor and cradle to change the trans anyway

Rickw wrote:

87TurboRiviera wrote:

Just bought a 95 riviera and a 97 riviera engine.... was wondering what all i will need to mod to drop it into this car.

This was your first post.
It's a bit confusing now because you start off saying you need to replace the engine and you have already bought one, now you say all you need is a transmission and radiator.?????

And another post you inferred you had a whole 97 car to take parts from. Very confusing.???

this.

Yeah, it's still clear as mud to me.

I have a 95 riviera......... the Transmission is bad in it.....
i also have a 97 riviera that the body is wothless.... can i take the motor out of the 97 and drop it into the 95?


DOes that make more sense?

87TurboRiviera wrote:

I have a 95 riviera......... the Transmission is bad in it.....
i also have a 97 riviera that the body is wothless.... can i take the motor out of the 97 and drop it into the 95?


DOes that make more sense?

The answer is YES.. we had a member do it "palermocorey" he is still around here and maybe he can link you to his thread about it.. You will need to swap the computer out of the 97 int o the 95 also.

is the wiring harness just plug and play?

87TurboRiviera wrote:

is the wiring harness just plug and play?

you'd also need the 97's wiring harness... and yes it is

87TurboRiviera wrote:

is the wiring harness just plug and play?

definitely not. The engine and transmission harness - you'll need the entire '97 harness. I'm not sure what you'll need to do to connect the PCM to other components, like the dashboard and gauges, hopefully the '95 is the same as the '97 in that regard. Only having both FSMs along with full wiring diagrams will tell the whole story.

thats what i am trying to find out.... I hae both complete harness's and PCM..... What im trying to find out is Both years have an OBII port under the steering wheel so i assume the wiring to it is correct. That wire runs to a port on the fire wall and the motor and tranny harness's pkug into that..... So in theory with the Newer pcm it should be drop in, hook up plug in and play..... I wouldnt see this being that hard.... its not like chaning to a completely different model.. i.e. Swapping a 97 into a 88.....

only thing diffferent with the 95's vs the 97, was the engine and tranny and OBII PCM....

The transmission harness is different, the '97 had a lot more electronic control for the 4T65E than the 4T60E of the '95 and '96, which still used a vacuum modulator for shift control. So that portion of the harness at least will be different. The engine sensors are probably similar, but it's Series I to Series II and I'm just not sure what you'll find. I would expect you to want the entire drivetrain harness from the '97 to accompany the PCM. I would expect you would also need to replace the PCM harness as it runs to the firewall, which may involve more internals. I'm sure the OBD-II PCM will have a different connector than the OBD-I PCM connector.

wow.... I have the 97 engine complete and wired up with PCM.... I know the harness's are different between the 95... no one is getting this.. and making it hader than it should be..... the port on the firewall is it the same port between years? thats waht i need to know.....