Major Catslammer

Needing some advise. I have a 1994 C4 with 235k that has the P engine. Blew up last week and have found a 70k 1996 engine & transmission that comes with engine computer and wiring also. Would this be a plug and play swap? Would I just use my current wiring or the one on the newer engine. Would there be complicated programing involved?

What I am looking for in the way of advise is this swap advisable?

Are there compatibility issues for the transmission from 94 to 96?

Thanks in advance for any input.

Thorr

Hi, '94 was OBD 1, '96 switched to OBD 2. You'll need to swap the harnesses, computers and sensors. You'll be better off that way any how, the engine will be more efficient and run better on it's own computer. You'll have to have mileage reprogrammed, so write down your current. Makes it an easier sway to do everything ECM, harness ( when needed ) and engine as matched sets when you can.

mtwoolford

hey, I like the idea of using the 96; the 96 has the much improved vented opti with all the extra necessary pieces already in place. HOWEVER, I don't think the change over to OBII would an added effort. Beside the wiring harness and new computer, you'll have to change over to OBII cats, which are the same as OBI cats except for the additional bungs for a second O2 sensor.

Retro fitting the 96 back to OBI status would be easier; the timing chain cover has a port on the lower passenger side for the crank position sensor, something not found on OBI cars; this can be simply blocked off; I believe the 94 exhaust should bolt up. Other than that it should pretty much be a bolt in.

Or as the old mechanic said: "Everything fit. Almost".

I'm not saying that the OBII system wouldn't be a upgrade, I just think the end results might not justify the effort involved...but I'm certain it could be done...and I'm sure that there would be some overall improvement.

Good luck; sounds like the original engine went the extra mile for you. And then some.

aboatguy

I agree an OBDI conversion of the 96 engine would be the easy and cost effective course of action.

Mike

Mr Mojo

I don't see any problems here, pull out the '94 and put in the '96 using the '94 harness. After all, the blocks are the same as well as the heads and intake. Any accessories such as A/C and alternator etc can be reused from the '94.

Paul Workman

And, keeping it OBD-I in many states (e.g. IL) makes, it exempt from annual emmissions testing - which would (to me) be an attractive "feature" when deciding between a 94 and a 96.

Then again...that may be a moot point, if the car is registered as a 94, then it is also listed (I suppose) as an OBD-I, and therefore the OBD-II issue may never come up.

I'll shut up now...

P.

96GS#007

This is wrong. The mileage is stored in the CCM, not the PCM. There is no need to have it reprogrammed.

Bandit's C4

Keep an eye on the transmission/torque converter side of the equation.

Starting in 94... changed over to 4L60-E with more electronic controls.
The 4L60E was improved in 95 (enhanced clutch controls and a lighter/stronger TC)

Ref: The Complete Book of Corvettes by Mike Mueller
Revised and updated 2011

96GS#007

'94-'96 cats are the same. The passenger side cat on the '94/'95 has the aft bung just like the '96 cat since the '94/'95 cars also had an aft o2 sensor on the passenger side. The aft bung on driver's side of the '96 is in the exhaust pipe, and not part of the cat. Even if it was (and I can guarantee you it is not), it would take an exhaust shop about 15 minutes and $20 to add a bung....which they can also do to the exhaust itself.

Key differences...
- The '94 ICM is different than the '96
- The '94 opti is different
- The '94 coil is different
- The '96 engine has a crankshaft position sensor (CPS)
- The '96 PCM will not talk to the '94 CCM

Another person touched on the transmission being different.

The easiest thing (and closest to plug and play) is to install the '96 engine and run it using the '94 PCM and wiring harness. You'll need to buy an adapter to hook-up to the Opti (many people have converted to the later style Opti, this is no big deal). You'll also need to swap over the '94 ICM and coil (they will bolt in). The CPS will remain unused and installed in the front cover. If there are any other minor differences, simply swap over those parts...likely a sensor or two...from your '94 engine.

Do not make the swap to OBD II unless you want to do a lot of work.

Major Catslammer

Thank you all for the information on the engine differences. Confidence is high that I will be able to take care of this one myself by using the 1994 parts on the newer block.

Does anyone have an opinion on the use of the '96 transmission? Very willing to admit that I know nothing about automatic transmissions past a turbo 350. Know enough to understand that the 1994 Corvettes interface plugs and computer control are probably more of an issue than the six bolts on the housing. Thank you in advance for any advise for dropping a '96 transmission into a '94 Corvette. Is this swap going to cause problems for the computers?