Altering ECU Code/Data - GM16 pin OBD-II

[xxalexx at ix.netcom.com]

> From:          martin at mgass.demon.co.uk
> To:            diy_efi at efi332.eng.ohio-state.edu
> Date:          Fri, 23 Jan 1998 22:36:28 +0000
> Subject:       Altering ECU Code/Data - GM16 pin OBD-II
> Priority:      normal
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> I want to know how to alter parameters on this complicated (surface 
> mount EEPROM type) ECU. (SimTec)
> 
> So far I have found out the following :.
> 
> - Looks like Diacom is for monitoring only.
> 
> - Query still in with CarComp Inc.
> 
> -I know that Superchips know how to re-program via the OBD-II 
> interface (which by the way I think is the ISO9141-2 and not SAEJ1850 
> interface 'cos only pins 3 thro 7, 12 and 16 have physical 
> contacts)...Note the SuperTuner.2001 looks interesting.
> 
> - Anybody else know how to do it ?.
> 
> - I guess my real quest is how to get a 1996 GM2litre 16V to run fully open loop 
> for performance reasons only.  The CAT can be put back when returned to 
> road use.  In the UK Group N ECU's were available (189bhp) for 
> pre-CAT early (non-EcoTech) 16V units, but not for later ones.
> 
> Martin
> ----------------------------------------------------------
> martin at mgass.demon.co.uk
> ----------------------------------------------------------
> 
You could try a simulator circuit for O2 sensor, then offset air flow 
voltage.  Our maybe just disconnect O2 sensor, apply voltage of 0.1 
volts if needed, the computer will then reprogram itself rich.
Alex