Nissan Interfacing Project

Hello everyone,

I have recently taken a newfound interest in the challenge of ECU
interfacing with my '96 Nissan Maxima (OBD-II compliant/VQ30DE
engine). Anyway, my goal is this - to basically make a little
monitoring station that can grab as much information as possible (no
matter how useless) while driving, so that it's real time. I'm a
Computer Engineer, so the hardware part isn't the big problem, but
the communication protocol(s) on the other hand are what seems to be
the problem. I have 3 proposed solutions to my project, and I was
hoping if I could obtain some clarification as to the validity of
them.

All the various sensors tie directly into ECU, and one can
communicate to the ECU through the OBD-II protocol, correct? But this
will only provide limited information, and won't allow any
modifications (if I wanted to tweak for power or whatever). So
strictly using OBD-II, I could probably obtain most of the relevant
information about performance, but I could not change anything,
correct? So this is one option for monitoring, just talk through OBD-
II.

If I don't want to use OBD-II (or as an extra), I could tie directly
into the sensors, correct? As in between where the sensors interface
to the ECU. This way, I wouldn't have to use OBD-II, and I could get
more 'raw' information. HOwever, each sensor is different, and they
all have different characteristic curves I'm sure, which makes things
a bit more difficult. But it's still an option, correct?

These seem to be the two obvious solutions, right? Now, the
limitation in both of these is that I cannot modify engine
parameters. For that, I would need to go directly into the ECU,
right? And modify it's EPROM. IF I wanted to do this, I would have to
obtain a memory map of the EPROM (which, by far, seems the most
challenging task) - but if I obtained this, or at least part of it,
not only could I view all the parameters that I could in the previous
solutions, but I could modify them as well, correct?

The last option would be nice, if viable, but I'm hoping that maybe
I could modify parameters through another mechanism (if I'm lucky).
Either way, like I said, the goal is to monitor, not modify - it
would be nice if I could do both though. Any comments are appreciated,

Jai

 
Received on Wed Sep 10 05:55:53 2003