I was wondering if you could put a 300zx ecu into a j30. Like does it have a same plug or do you have to custom wiring?

Seems possible. I can't say for certain as I haven't compared them so I don't know if any of the ECM plastic plugs are the same and line up. Going by my experience of a 1996 J30 computer not working for earlier J30s because it's a totally different plug and the 96 computers expect downstream O2 sensors. There could be more stuff different I am not aware of, but the year of each car's computer is going to matter somewhat.

Can you really get a 300ZX computer cheaper than a j30 one from ebay? I think it would just be easier to get the right one. What does the sticker on yours say? ex: 1996 ECU says (A18-F00 K00) BA

I found a 91 300zx ecu for $60 and I was just wondering before I got the go ahead and get it because I was thinking it would be tuned differently and maybe more power? My car is a 94.

I can't say for sure it would be tuned any differently. I personally don't think you are going to get any more power and the chance that it won't swap in isn't worth whatever tiny gains there could be from any different tuning. You have to realize that people with 300zx computers would get theirs modded also. I don't see any point in getting a 300zx ECU. Is your ECU broken? I would replace it with the same one if it were me and it needed replacement. I am seeing them on ebay for 15-20 bucks with a 30 day return policy.

Alright I was just wondering if the 300zx ecu would do anything different but I’ll not buy it then if it would pretty much be the same.

it might have different fuel tables or some slight programming tweaks but I wouldn't risk spending money on the hope it makes some worthwhile difference. If you could find some information that says the J30 ECM was conservatively tuned and the 300zx one will somehow turn more fuel burning into more HP and you want to spend the extra gas for that AND you know that the plugs will work without re-pinning it or swapping the entire engine harness, then I could see it maybe being worth it.

These cars have been out for a while now and I think it that was something people found was easy and worth it, you would be able to find some information suggesting it.

Also, like I mentioned before, if the 300zx ECM was tuned that well people wouldn't pay to upgrade them and send them off to be reprogrammed, I would think.

I have a '93 J30 and when I was looking into TCM & ECM availability for a reference , never did buy , I believe you'll find model YEAR to be very very significant , now going from a 300Zx to a J30 there may be like the previous year OR the following year is what will actually work - like one is ahead of the other car in parameters / spec's. And a one year older OR one year newer is what MAY possibly cross-match ??

1996 is OBD2. I was moving my stuff into a 1994 and I had to change all the harness stuff to be able to read the computer with my OBD2 scanner. I think you have a chance that pre 1996 computers might be similar enough but there is a good chance that as mac says it is just a year or two that interchange. if so, it would be like 93-95 could interchange and then 96 and 97 could maybe as well.