1996 3.4DOHC INTO '95 Z34

[95dohcBlackZ34]

good point, will check too see if there is a difference in the sensor wiring.

[dohcfiend]

i am not sure of all the wiring differences. but 91-93 have map systems, 94-95 are MAF systems, not completely sure on 96+ i thought i saw a map sensor on the neck between the uim and the tb. so i would venture to say it is a map system. but that is easy just leave the map alone and install your maf sensor.

umm.. the egr's are different. as far as the o2 goes they both look like heated, 4 wire o2 sensors. the 91-93 were 1 wire o2's.

those plugs u were asking about on the front, they should plug in to large plugs right in front of the computer. they go to the injectors, tps, iac, cam bank sensor, coolant sensor on the bottom of the lim, o2, and that red/light blue plug onthe front i noticed it wasn't hooked up, it goes to a little electric vac valve that is for the charcoal cannister i think. if u need a pic i will ge u one. also i have an xtra 1 lying around if u need it i will give it to ya. u can switch that entire harness with the 95 one and plug it right into your 95 ecm.

as far as the sensors go on the bottom end i can't help u much there cause i really didn't look at the bottom end of the 96 motor.

i have a question for u? does front head have a green 1 wire sensor screwed into it? nevermind i see it hanging under the crossover pipe.that is all i can think of for now.lata.

[Cliff8928]

That valve on the canister is the purge valve. Later on they located it other places but they do the same function, this connector usually tends to be red many cars.

As for the coil packs, you should have more than enough existing wire to re-route them to the 96 location.. just pull the wires through the harness and back around..


Cliff Scott
89 BerettaGT
89 Volvo740

[jmgtp]

i am not sure of all the wiring differences. but 91-93 have map systems, 94-95 are MAF systems, not completely sure on 96+ i thought i saw a map sensor on the neck between the uim and the tb. so i would venture to say it is a map system. but that is easy just leave the map alone and install your maf sensor.

It doesnt matter. You just use your 95 electronics, the 96 may use the same exact maf but theres no reason you couldnt use the 95 maf. The 96 does have a map sensor in the intake arm, used I believe only by the ecm for egr conditions. You just wouldnt use it with the 95 ecm. The egrs are different between 95 and 96, but you can just use your 95 intake manifolds and use the 95 egr and it wont be a problem. The only thing that would be a problem with respect to the egr is the tube. You would have to adapt the 95 tube to the 96 exhaust manifolds (which you have to use, cant use the 91-95 exhaust manifolds on the 96+ motor) or make a hybrid tube that mates to the 96 exhaust manifolds and the 95 intake manifolds. Personally, I would just keep the 96 intake manifolds on. Its really not much work at all to make your 95 stuff work with them. Run a vacumn source to the purge canister from one of the extra ports on the TB and then extend the TPS wires a little bit (or rework the harness some and they just might reach). The 96 uses the same exact TPS, IAC and Temp sensor in the lower intake so those will plug in no problem. You would have to make a custom egr adapter plate to use the 95 egr on the 96 manifolds.

[95dohcBlackZ34]

Good point everyone, and especailly john!
You would have to adapt the 95 tube to the 96 exhaust manifolds (which you have to use, cant use the 91-95 exhaust manifolds on the 96+ motor)"
I talked to my mechanic today and he said that he is looking forward to doing the swap. I appreciate him saying "looking forward"! the current 3.4 will be pulled around June 18-19th.. thats when it's booked in for the swap. it;s been since last may that I've driven my baby, I am more than horny to get rid of this GD 92 topaz (v6 mind you) and get the Monte back on the road! The help everyone here has given is much appreciated so far.

[95dohcBlackZ34]

You would have to make a custom egr adapter plate to use the 95 egr on the 96 manifolds.
Yet another good point.

[95dohcBlackZ34]

My car is OBD 1, NOT 2, GD IT!!! may as well get a new ECU.. ahh well guaranteed functionality- now all to do is figure out this wiring stuff

[jmgtp]

My car is OBD 1, NOT 2, GD IT!!! may as well get a new ECU.. ahh well guaranteed functionality- now all to do is figure out this wiring stuff

You dont need OBD II to run the OBD II engine. The OBD I computer will run it just fine.

I give up, it seems like such a futile effort to get it across that the OBD I computer will run the OBD II engine.

[dohcfiend]

jmgtp pretty much hit the nail on the head.

that was the whole reason for bringing up sensor interghangability. i checked the bottom end for u. from what i see there are only 4 sensors! 1 is in front i am guessing it is for your ignition. probably a pickup and/or crank position sensor. 1 (if you looking at it from the front it would be on the right side) it is probably for your oil pressure guage/dummy light etc. 2 on the left side 1 is a knock sensor and the other i am sure about, it has a 2-wire connector on it. i am pretty sure the knock sensor is the same, i think the ignition is the same(cause coilpacks for both years have identical connectors on them) there might be some difference on the oil press sensor but it just screws in and is fairly easy to get to. the last sensor i don't know wtf it is for, but i will make an effort to find out. all the sensors on the top 1/2 are identical except the egr(that doesn't really count as a sensor).
i would ask jmgtp but logic would dictate that if 100% of the sensors on the top are the same probably the sensors on the bottom might be the same also.
other than the egr sounds like a "plug-n-go" setup.

the only other things left that i can think of at the moment are fuel lines and throttle cable/cruise cable(if applicable for the cruise).can't help u with that.

[jmgtp]

TPS, IAC, Coolant Temp (in lower intake) - All the same. I made the throttle and cruise cables from my 91 work without issue on the 96 top end so those shouldnt be a problem. But if youre using the 95 top end then you wont even have to worry about that. This swap is doable, and should be almost a direct swap. Fiero guys swap this engine all the time and a lot of them use the wiring harness from a 91-93 so they can use the 5 speed code with out a hitch, even the guys using 96/96 engines.

I *think* the only problems you will run into on this swap is the egr tube and maybe the alternator connector.

[95dohcBlackZ34]

ok... understood. I'll use my existing OBD I System jmgtp, thanks. I assume the motor doesn't even know the difference.... with minor differences btwn. the two model years
The top end stuff will be fine, agreed. The EGR tube will need some lengthening indeed; I am keeping the 96 top end, the whole 95 engine is coming out, if I can salvage a few things from it good, but since I have the complete exhaust manifold, throttle body, etc etc on the replacement motor everything will remain the same.
Is the alternator, and serpintine belt from the old motor identical? I'm assuming yes-
and dohcfiend says "i would ask jmgtp but logic would dictate that if 100% of the sensors on the top are the same probably the sensors on the bottom might be the same also" thats also a very good point. Plug and go I hope so.
"you can be a pain in the ass, but you can never be too sure!"
Thanks for the help so far. I want to make a small site with info on how to replace the 95dohc with the 96+97 model years, so that'll be interesting. I'll also post some pics of the swap (motor out- June 19th, can't f*in wait!)[/img]

[RednBlack]

Why not just use the block? I guess it depends on what blew.

[95dohcBlackZ34]

pretty much everything blew, when my TB snapped the valves bent and I ended up with a 3-cyl engine, the list goes on. On top of it the car has been sitting in my garage all snug for just under a year- Figured a swap was the best idea. I don't even want to deal with the old motor, let alone look at it !

[jmgtp]

yikes... definetly change the belt on that 96 before dropping it in. The 91-95 is supposed to be a non interference design, meaning the valves shouldnt contact the pistons in the event of a belt breaking -but it has been known to happen. The 96 engine is not an non intereference engine, meaning youre pretty much guranteed to bend some valves if the belt goes. Tbelt parts ~250 USD, via gmpartsdirect.com, shipped to your door.