endwrench

Hi,

I have a 1996 Z28 with a bad motor. The only engine I can find locally is a 1994. I have searched the board for the answer and I believe this will not be a problem as far as running is concerned but I am not sure about retrieving codes. Can this still be done thru the OBD2 diagnostic connector? Are there any other pitfalls I may experience. Should I try to get the OBD1 computer too? Mine is 6spd. I don't know what the 94 is. Thanks,

Todd

Injuneer

You're going to have a problem with the fact the 94 doesn't have a crankshaft position (CKP) sensor. The PCM will set a code if there's no CKP. Won't hurt anything, but will prevent the PCM from detecting misfires. You could have the CKP function removed from the OBD-II PCM with programming.

You will also need to put your '96 100Kohm knock sensor in the '94 block, replacing the 4.5Kohm OBD-I sensor.

You will have to transfer the EVAP system vacuum detection switch from (on or near) the passenger side valve cover to the 94 engine.

You'll have to transfer the drivers side exhaust manifold, since the OBD-II dual cat Y-pipe has a wierd 3-bolt triangular flange.

You'll have to eliminate the Opti air supply and vacuum hoses, since the 94 Opti will have no place to connect them.

There are also some electrical and vacuum gadgets incorporated in the 96's AIR pump system that will not be present on the 94 engine. The exact details will depend on whether your 96 had the AIR pump recall work done.

mdacton

whats wrong with your 96 motor?

you could pull the timing cover and stuff off and swap it all over while its out...thats the easiest way, all you need is the gaskets.....also use your obd2 reluctor whl. timing cover, knock sensor, balancer

I would use the OBD2 opti also....wouldn't use a used obd1.......

you could probly sell off those parts you don't want and if your block is o.k. let me know

Injuneer

The swap would have to include the cam, if he's going to use the 96 vented Opti.

mdacton

yeah forgot about that.....so might as well put a new cam in it too

endwrench

Wow! Thanks for the great detailed responses. Looks like the problems are not insurmountable. My 96 engine had a total meltdown overheat condition due to a bad radiator. Got so hot it melted the middle out of the temp sender! Then it hydraulic locked and bent a rod. I've heard of the problems with the earlie Opti system and that will be my only concern I think at this point. Much appreciate the help!

Todd

Red-LT1

Your going to want to make sure it doesn't throw a code though, even if nothing is wrong with it. You might get a slight loss in gas mileage. And these days, gas might as well be gold

Rbwin96z28

I am actually in the middle of the exact same swap, I did a 95 into my 96, also with the 6 speed transmission. I am using the 96 obd2 harness but i am not getting any signal to my fuel injectors to fire. I was wondering if you had any similar problems and if you might know some advise on how to get it running. I was thinking i may need to program the obd1 pcm for the 6 speed transmission that I put on the 95 engine that is currently programmed for automatic but if i don't have to i dont want to.

Injuneer

There's a huge difference in the vehicle speed sensor (VSS) pulses per revolution between the 4L60E (40 pulses/rev) and the T56 (17 pulses/rev). Speedo/odo will be way off. Just have the PCM reprogrammed for the correct trans. But the incorrect program should not prevent the injectors from firing.

”endwrench” hasn’t signed into this site in almost 15 years.

Have you scanned the PCM for codes? There are codes for injector circuit faults and for failure of the fuel enable signal to the PCM from the PASS-Ket (VATS) system. The 96 sends the signal from the BCM, 95 sends the signal from the theft deterrent module (TDM). PCM terminal should be the same. Have you verified 12 volts on the pink wire in each injector connector?

cbccadet2002

Don't most people convert the 96 to obd1.5 for tuning easement? Are you just trying to drop the whole 96 assembly in, or are you going to switch your 94 stuff onto the 96 short block? Couldn't he just run his 94 ecu and tune stuff out with tunerpro? Sorry to hear about your "melt down." Bummer man, best of luck

Rbwin96z28

Yes I did check that and I do have 12 volts going to every injector. I scanned for codes and the only thing that was showing was mass air flow code 0100. I have the pcm for both engines and both harnesses, I had the 95 harness and pcm hooked up and had ignition and engine turned over, but I guess I wasn't getting the signal for fuel system to prime. Can I move the pin on the connector to the correct place to get signal to the pcm from the tdm, to allow the fuel to work?

Injuneer

Maybe the Corvette LT1 is a candidate for an OBD-1.5 conversion, since the Y-Body actually had OBD-1.5 programming. But the OBD-1.5 interim system was never applied to the F-Body. Yes, the F-Body got the modified 16-pin OBD-2 DLC in 95. But GM jumped directly from OBD-1 in 95 to OBD-2 in 96 on the Firebird/Camaro. And, yes there is OBD-1 D-I-Y tuning software available. Keep in mind that OBD-1.5 is a made-up nomenclature for GM's hybrid system with both OBD-1 2-digit trouble codes and 4-digit OBD-2 codes.

He can run the 95 engine with the 96 PCM. The parts that need to be relocated are outlined in post #2 for a 94 engine. The exception on that list for a 95 engine would be that it already has the Opti vent components.