How many injectors drivers ?

[edsz31]

I was under the understanding that 1984 to 1987 ECU's had 2 injector drivers, These models had a recall, the factory rewired the injector harness so the engine ran on only two injecter drivers

I thought 88-89 ecu,s have 6 drivers, So if you used a 88-89 ecu on a pre-1987 you had to rewire the injector harness and then install resisters if used with mercedes injectors.
I know 1987 use side feed injectors like the 88 and 89 ecu.s

I have a 86 with a 87 ecu, the injector harness is recall, 2 signals. no resisters with the benz injecters.

Does it really matter what ecu for what year after the Nistune board is installed ?

[Matt]

From all early model JECS ECUs (R31, Z31...) I've seen there are only two injector drivers and single coil ignition

Hitachi ECUs (HR31, CA18, Z32, R32 etc) use six injector drivers and multi coil ignition

For most of the part it may not matter which software you put on which hardware for the JECS ECUs (Z31)

However I have found with later model ECUs that putting a different ROM image on the ECU may affect the functionality available or not even run correctly

Some examples are such as using Z32 US image in Z32 JDM ECU does not inject properly on bench and S13 KA24DE running manual image in auto ECU has RPM cuts @ 5000rpm which are not TP cut (ie shouldn't happen)

What I think happens is that as ECU hardware is revised, that sometimes the ECU software is altered to suit. There are programmable logic devices in these ECUs and if their firmware is changed, sometimes the ECU software must match these in order for the ECU to have all functions operate correctly

This is why we try and match the same or compatible ROM image in boards shipped out so there are no problems with customers vehicles

At the same time, the Z31 for example being one model have variations of software options (eg auto/manual, cali/fed, turbo/na). The 1984-1985 ECUs are quite different and ROM images are not compatible with 1986-1989 models

The 1986NA Z31 are the same h/w setup as R31 with two chips, one containing overlapping maps on the 24 pin (1K) ROM vs the 28 pin (16K) ROM and have different scalings and constant locations compared to other Z31 ECUs

The 1986-1987 Z31 ECUs have memory locations (as I painfully found out) for Battery Voltage and Fuel Temp in different locations

The 1987-89 ECU hardware starts moving towards SMD technology and Nissan uses pads for external device connection (which NIStune uses but I dont know why exactly nissan put them there)

The fault codes reported for Z31s are different. Some use 4 memory addresses whilst others use 2

So there are a lot of variations for the Z31 in the US. I dont know why that is the case, compared to most other Nissan models (EDM/JDM/ADM)

But we try and fit the most compatible board. Your new board posted out has a 1988 SS VG30ET image in it which will run fine in your 1987 ECU and has been used by a lot of people

[JR50ANNZXT]

I am faced with using low impedance injectors ( like Mercedes) on a 1988 ECU made for High impedance injectors. I know about adding the resistors but it would seem that this is not the best solution since it limits current perhaps needed by those low impedance injectors and likely affecting the latency value as well.

Would it not be better to change the two injector drivers to a higher current handling device capable of handling the current for 3 low impedance injectors in parallel? ( like the original 1984 ECU did )

Matt, I can only assume you have schematics for these ECU's to do what you have done. Can you make available the schematics or at least the injector driver circuitry. I would like to contribute a solution to change out the injector drivers to a beefier device capable of the higher current. Just need to know the drive circuitry and the task should be fairly simple.

Another option would be to add some external FET's to do the same function but drive them with the original Hi Z injector output.

Let us know what you think,

[GZ@hybridka]

There is a hardware solution for properly peaking and holding current to use low impedance injections on a high impedance system.

Check this out, the board could be used as it is, or you could setup your own circuit.

http://www.jbperf.com/p&h_board/

The original nissan injector output/circuit should not need any modification.