Bruce_Aldridge

OK, it's been a long times since I've posted anything, My 1982 ZX is officially dead. Fortunately my wife survived. That said I bought a replacement 1983 ZXT. Right now it runs like crap, some fresh gas and a new fuel filter is helping, the engine runs great at idle (way to high at about 12-1400 rpm) but backfires and boggs bad when you try to accelerate. The head temp sensor is disconnected (was told it read backwards) and the ECU has been changed to a 1984 model. From reading it looks like the only way to get the idle down is to get the ecu to do it. So....Question number one....

(1) Anyone have any links to the ecu conversion that I might be able to wrap my head around the why and how.

(2)what would make the temp sensor read backwards (an how to correct it)

(3) other than fuel and ecu connections what I'm I missing on the bogging?

(4) since the gas sending unit works haphazardly does anyone know if the QD connector is permanently fastened on? The three round plugs move but seem to be permanent, don't want to force them and make it worse.
Thanks B

New one on the way home, Thanks Nick.

rogerz

your post makes absolutely no sense. Is someone feeding you a line of s### or are you just posting to hear yourself talk? when you say the temp sensor is backwards which one are you talking about - the one for the coolant gage or the one that feeds data to the ecu (CHTS). they can't work backwards unless someone reversed polarity of the battery. the only way to put an 84 ecu into an s130 is to install a Z31 MAF in place of the S130 AFM. what are you calling the gas sending unit? perhaps the fuel tank level sensor?

Bruce_Aldridge

Then I'll try to clear the fog for you. No, got tired of talking BS when I was a teenager, In the post I said head temp sensor, That would be the one located between the 5th an 6th plug I think. The previous owner said that he had replaced it several times and that it gave backwards readings to the ECU (as in reading hot when cold an cold when hot) an yes it may be a line of BS.....but the polarity hasn't been reversed at least on the battery......his wiring? I have know idea which is the reason that I'm looking for a link that can tell me what the H@@@ is going on with the ECU conversion. An yes he said that he had to put a Z31MAF and a Z31 distributor in.

As for the gas sending unit that would be the one located in the fuel tank ....4 wires on a QD fitting that appears to be permanently attached...don't want to break them by putting to much pressure on them to see.

NismoPick

Who did you get the 83 ZXT from? There are a few guys from GA on the 280ZX Drivers Facebook group, one of them I know did the Z31T ecu swap and never got it running quite right.

So, to dig in:
#1: I have attached my zip file of all the important docs and steps for the swap procedure.

#2: Have you yourself verified that the CHTS "reads backwards"?
Ohm sensors can confuse people... the CHTS ohms go down as temp rises, and ohms go up as temp drops (specs from FSM also attached). If the ohms are changing as the temp changes, this isn't the problem.

#3: Verify that you actually have a turbo ecu (CA or FED?), and check your MAF. Does the MAF have a yellow (FED) or blue (CA) sticker?
Check ecu diagnostic codes.

Also make sure the timing is correct (24* BTDC).

Bruce_Aldridge

Thanks NismoPick, this should get me going.

Bruce_Aldridge

Nismopick, it's running pretty decent right now, replaced the fuel tank, hooked up the sensors, changed the timing (off a tooth). Then solved a problem that the original mechanic and Nissan couldn't solve. I talked with the mechanic that had serviced it over the years, seems that it had never ran correctly (from 1991), he had swapped all the electrical parts from another car in an effort to fix it. Nissan gave up on it after a month. It sporadically ran badly....I found a pinhole leak in the water hose running behind the distributor. When the engine was warm it would spray the distributor and short it out. since the water was warm it evaporated before you could see it. I changed the hose and it was like driving a different car.

NismoPick

Good finds!