1JZ datalogging options?

[mkiiichip]

You are correct in thinking the supra has no serial data. Dont bother purchasing scanner plugs for OBD1 Toyotas, ill explain.

I wonder what other stuff can be read from the DLC?

As you have already figured out VF is available from the diag block, there are only a few more signals available so dont get to excited.

IG- is RPM
FP is fuel pump signal voltage
OX1 is O2 voltage
TE1 is a check connector (for fault codes, check mode, etc)
+B is power
E1 is ground

As seen here. Called "Check connector" or (as i call it) Diag block.
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=48

These signals are all checkable with a voltmeter, thats why nobody uses a scanner for toyota OBD1 applications.

IDK if you have seen this before but this is a very detailed explination of what VF is. There is another good thread on how to use VF while tuning, I just cant find it right now.
http://www.supramania.com/forums/showthread.php?39856-Information-Vf

 

[destrux]

Thanks for the info, I figured at least a few people here had to have known about this.

I found another good article about it, the VF1 pin specifically...
http://alflash.com.ua/vf1.htm

Looks like the 1JZ, since it's a pressure sensor application, has only a 3 step output on VF1 for fuel trim. Still very useful, just aim for the fuel trim to be at 2.5v at warm idle and steady cruise. I checked my car at a warm idle after I reset the ECU and it was at 2.5V then moved to 0V after a few minutes.

I found a nice schematic online for a digital LED bar gauge that displays on a 0-5v range. I'm gonna build one and put it on the dash to display this full time, it'll make tuning easier and let me keep an eye out for problems even after the car is tuned.