Nissan ECU Tuning

danworth · Joined: 25 Nov 2004 Posts: 7

Ok i have 2 128k / 16kb bins ive merged them i can see the first half 0000-3FFF is one bin and 4000-7FFF is the other bin, i programmed the eprom (27C256) now i want to switch between the 2 bins, i read on the old ztechz forum you short pin 14 to vcc for one bin and pin 14 to gnd for the other, ive tried this and it doesn't work any one can help please?

also a diagram indicating the notch on the eprom and the pins used,

Thanks.

rybowen · Joined: 08 Sep 2005 Posts: 118

THe quick & dirty way to do it is solder a 10k resistor between A14 and VCC (between pins 27 & "28"). Solder a wire to pin 27 also. Then, when you install the chip, leave pin 27 hanging out of the socket. Ground the wire for the bottom bin, and leave it floating for the top bin. Make sense?

Pin diagram: (notch at top, pin1 upper left)

+--------------+
VPP |1 +--+ 28| VCC
A12 |2 27| A14
A7 |3 26| A13
A6 |4 25| A8
A5 |5 24| A9
A4 |6 23| A11
A3 |7 22| /OE
A2 |8 21| A10
A1 |9 20| /CE
A0 |10 19| D7
D0 |11 18| D6
D1 |12 17| D5
D2 |13 16| D4
GND |14 15| D3
+--------------+

danworth · Joined: 25 Nov 2004 Posts: 7

fantastic, do i really need a resistor, as i need to do this tonight and i dont have a resistor.....

danworth · Joined: 25 Nov 2004 Posts: 7

i have a old ECU here im looking at the resistors i cant find any 10k ones (Brown Black Orange is that right???)

what else will work???

danworth · Joined: 25 Nov 2004 Posts: 7

never mind found one. i'll give it a go now let you now how i got on.

danworth · Joined: 25 Nov 2004 Posts: 7

Great worked a treat! now i can go to bed!

nice one mate.

rybowen · Joined: 08 Sep 2005 Posts: 118

Glad it worked for you. You can use any resistor pretty much.

FAST-TRACK · Joined: 21 Apr 2004 Posts: 160

First time ecu read data 4000-7FFF. When you connect GND + PIN 27 ecu will read data 0000-3FFF.

pom_vr2 · Joined: 13 Nov 2005 Posts: 1

Vetal · Joined: 08 Feb 2006 Posts: 120

Why do you need resistor?
P.S. Works with just a switch for me (CA18DET) Smile

Doni666 · Joined: 02 Dec 2004 Posts: 59 Location: Kotka, Finland

oops · Joined: 02 Jul 2004 Posts: 100

will this work with a 512 PROM?

Regards.
_________________
changed my user name

Vetal · Joined: 08 Feb 2006 Posts: 120

LMQT · Joined: 06 Aug 2005 Posts: 144 Location: France

deviousKA · Joined: 14 Jun 2004 Posts: 106

It would all depend on the switch, if you dont have any problems at all with on the fly switching without using pull resistor setup, you could say you have a nice fast switch Smile

All mechanical switches are going to have some "bounce" to them anyways, using a resitor to pull high and then switching to ground would be considered marginally better than a straight up switch.

Using something like a flip-flop (as calum mentioned a couple times) would be the best way to go, theoretically. I dont think rom address switching is a good idea during actual "real time use" (like nitrous or maybe some sort of rom switch launch limit at high rpms or load), Your switching a whole lot of code at one of the worst possible times, only to obtain a few setting differences. Better to just save the rom address switching for idle.

Using some original ecu inputs, with the code modified to use them in some certain fashion (like fuel or timing map pointer switch) would be best. You could then be safe to use them dynamically for all kinds of things, having proper timings and consistency.