columbiansnow

Hi, first of all I know I'm supposed to use the search bar, but I'm on my phone at work and this website is definitely not optimized for mobile on my phone, and it doesn't let me use the search bar.

I have a 84 z31 n/a.

Basically I'm about to do an ecu swap most likely. And I was wondering if I swap from another 84 z31 (same model) do I need to reflash the ecu or is it mostly plug and play?

Reason I'm doing the swap is my car dies every 2 minutes. The fuel pump, fuel filter, and fuel pump relay are all new and they work fine. And again because I'm on my phone I can't seem to find a good link to the FSM and my chilton's repair manual is still shipping

rogerz

don't know what you think flashing is? a term usually used when renewing a rotating field generator and need to establish residual magnetism. nothing i know of needs doing with a z31 except plugging it in. I would first look for some loose wires or connections. either main battery cables or check your fusible links. check all your connections for corrosion. is your battery tied down or just sitting loose in the tray. is the battery any good get it load tested at battery shop. using your experience with an 09 mustang is really specious reasoning - the kind that makes you spend money when you don't have to. The nissan fsm is much better than chilton's and more likely to be correct.
in your picture I see no battery hold down and cables look suspicious. at least you are now asking semi intelligent questions.

columbiansnow

Ok thanks for the reply, so there isn't any corrosion except on the battery terminals when I first got the car (already cleaned) battery is fine got it tested. And everything seems to be properly grounded and no loose connections. So the battery isn't strapped down, I didn't think of that so thanks for the info. But would it be an issue if it's just idling? When I changed the ecu for my mustang the ford manager said they needed to "reflash" it so my car would run properly. I assumed that meant tuning with a flash tuner? But it's obd2 so I don't know how to reprogram an obd1 myself. But just plug and play simplifies it a lot. Thanks. Is there anything else I'm overlooking that would make the car shut off randomly? I can hear the relay click and the fuel pump shutting off before the engine dies, if that helps at all

rogerz

listening to someone about a car that is 20 years or so older than the stang is foolish. You have a loose connection or intermittent ground that is shutting off power to the system. the fact that it starts right up again indicates things are okay when it is running. forget obd anything with a z31. have you checked and reseated the three connections to the ecu? check the battery cable terminations at BOTH ends. tight and clean of corrosion if you aren't grounded between the battery negative and the starter that can be the problem grounding only through the bell housing is not a reliable connection. now that you are not asking questions that sound like coming from a man wearing an aluminum to deter the martians. I'll share some more wisdom:

Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion. DON'T USE DIELECTRIC GREASE.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. Get new boots for power steering. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. You need to get the car realigned after messing with the front. Have your tires in good shape and rebalance. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone.

You either need a buddy to bleed brakes properly or drop a tube from the bleeder into a jar with some brake fluid in it. start from the farthest wheel rear right and proceed to the nearest winding up at the left front . If still a problem it might be the master. since the car looks beat I would take the calipers off and clean and lubricate them. pay attention to the part about clamp on terminals I'd just buy new cables and replace. A real battery shop can make up a set fro less than 25 buck. use a short negative to a bolt in the frame and then go from there to the starter. If you post a decent pic of the engine compartment right and left I might spot some other disasters.

columbiansnow

Ok, I officially don't care how stuck up you sound lol. Great advice here, I'll update this thread after I do what u said electronics wise (suspension will be done after I get the car running). And I'll post with pics. Thank you

NismoPick

To clarify your "flashing" question... not all cars are the same. What works for a Ford doesn't mean it will work for every car. Reprogramming a new OBDII (96+) ecu is required because the ecu contains the car's VIN. This is only required if you want to legally register and drive that car.

There's no factory flashing or re-programming the Z31 ecu, BUT there are two "hack" options if you want to TUNE through the ecu.
#1: Use Nistune: NIStune - Realtime ECU Tuning
#2: Use a pocket romulator: The ROMulator and Live Edit software page!

And here's the link to download the FSM:
XenonZ31 Reference

Online PDF's:
Index of /FSM/300zx

Now to the car dying issue...
It's either losing spark, or losing fuel / flooding.
So when it dies, check for spark and fuel. Then work backwards.

Defender405

The "bad ground" situation is a much greater factor on these cars than on others you may have worked on. I'm used to British cars where bad grounds are often a fact of life and really don't make much of a difference once you get the car running. Bad grounds on the Z31 will F' up all sorts of stuff, some things that you would never normally attribute to a bad ground. On these Z31s the factory ground through the block is sketchy at best after all of these years and really should be augmented. My car has an additional ground cable running to a bolt on the passenger side shock mount, this has helped eliminate a lot of the flaky electrical issues I had.
The other thing to check on is the vacuum hose on the fuel pressure regulator, really all of the vac hoses, but the one on the FPR can cause flaky fuel issues. Bad vac hose there caused mine to flood out intermittently. Not saying that's your problem but it is definitely a place to look.

86tcoupe

We reflashed E C U ,s on 96 to 99 ECLIPSE seems they did not meet emissions and we had customers come back saying it doesnt run as strong ...yeah no s__t the tech training staff told us we could try to talk the owner out of re flashing
your z31 is many years previous from that and reflash is just a tweak of the system not the complete mpi
You might open it up to see if you have a capacitor burning . That can do what you describe .