Help me solve this mystery - VG30DE Swap

[jdeck]

Let me provide some background for my post

I am trying to help out a neighbor who had some friends swap a motor for him and left him flat. I am hoping to help him figure out what to do with the car. If it's doable and a good idea I may try to get it running for him. Otherwise I would help him sell it or something in between. I am very familiar with working on Japanese cars and well versed with with Honda/Acura, Toyota and Subaru. I have a Subaru Impreza, 2006 WRX, 1998 2.5 RS that I ice race in the winter and a turbo 1992 Integra that I track Spring-Fall. I am not very experienced when working on Nissans, which is why I am here for help. Below is information that I got from my neighbor.

Here are the facts:
- He has a 1991 300zx (no rust, mint interior - very nice car)
- A few years back the timing belt skipped some teeth and trashed the motor
- He enlisted some car acquaintances to help swap a motor. They clearly knew enough and weren't hacks but they were also obviously not experts.
- He has a receipt for a JDM "90-95" VG30DE and paid $895
- After installing the motor, the car acquaintances swapped out the injector wiring for PHASE II plugs to match the new motor, they also installed the timing kit from Z1
- When attempting to start the car, the negative battery terminal arced and melted
- The car was towed back to his house and not touched since (I think 2-3 years)
- I inspected the negative terminal wire and it almost seemed like it wasn't connected to anything and they tried to start the car so it arced at weak point in the wire. I have never seen anything like it before.

Noted but not confirmed:
- He said he remembers the guys say that it could be a 1998 motor
- He said that he remembers the guys encouraging him to simply have a mechanic finish the car and that it was probably a simple electrical issue
- I truly could not figure out why they stopped working on the car from speaking with him. I thought maybe they felt that their input matched the pay and troubleshooting would put them in way over their heads. The car was also towed back to his home which was 45min travel time for these weekend warriors. However, this is all confusing to me since they had some kind of knowledge to swap the injector plugs and also install the timing kit. Isn't the best part getting a swap running?

Next steps:
- Is there a definitive way to figure out which motor this is? If it's a 96+ then obviously I would advise him to sell the car. I am aware that the lack of VVT and presence of OBDII would not make that a variable option.

- Thoughts on the arcing/melting of the ground terminal (common with these cars?)

Thanks in advance

[evildky]

Welcome to Nico!

This belongs in the Z32 area so i'll move it.

The 96+ engines do not have a VVT on the intake cams so it's pretty easy to tell, if you got a 96+ as there is no cam solenoids fo the harness to plug into.
As for grounding, there should be a ground wire from the battery to the chassis, about 10 ga, and one to a starter or bellhousing bolt, this one should be 8 ga or larger. toyota and mazda like to use a lot of smaller grounds, so if all they had was a small ground it won't take much cranking to melt the wire.

[elecfus]

that's not a wire it's a fusible link. fuses blow from extended cranking, especially older corroded fuses. the 240z has a fusible link around the starter that looks like this and the 300zx can have one around there as well. without any further details, we cant help. doesnt start, no power, headlights turn on, ECU led blinking? you should be able to get the lights and wipers working if the positive wire from the battery makes it to the fuse panel and ground makes it to the chassis so just check your main fuses and fuse box and try again.

[jdeck]

Thanks for moving the post (I realized after the fact). This info is super helpful. I'm going to check the solenoids on the the back of the engine. Here's a pic of the motor in the car as well. If it is in fact a 90-95, I'll have to chat with the owner to see if he wants me to try to get it running.

[elecfus]

haha oh wow. that thing was sitting out in the rain for some time.

[everpresentnoob]

Just one thing I notice off the bat, Compared to mine at least, your battery is backwards. On mine the posts are at the back near the firewall, positive is outboard by the fender. the neg lead is normally bolted to the firewall near that clamp you have that is empty... Is there any chance the cables were attached wrong? neg on pos and vise versa?

[jdeck]

Just one thing I notice off the bat, Compared to mine at least, your battery is backwards. On mine the posts are at the back near the firewall, positive is outboard by the fender. the neg lead is normally bolted to the firewall near that clamp you have that is empty... Is there any chance the cables were attached wrong? neg on pos and vise versa?

Haha oh man that would be something. So I haven't spent any actual wrench time on the car yet. I just wanted to check in with the owner, take some photos, research and get some input. If someone were to hook up any battery backwards all you would be doing is essential throwing full 12v to the car...of course it would melt the s*** out of the wire! I bet some (or multiple) idiots hooked it up wrong! I think I'll try turning the battery around and see if I can get the car started. I'll make sure to check the solenoids but I'm starting to think it's a 93+ VG30DE with the phase II injectors...

[elecfus]

wew just follow the big cables and the one that connects to the chassis of the vehicle and engine block is the negative. dont try to flip it around without doing this. the positive goes to the fuse box.