maf to map conv. requires vss prom change?

89gta5.7tpi · Post by **89gta5.7tpi** » Sun Dec 18, 2005 9:37 am

I'm in the middle of converting my 89 GTA 350tpi from maf to map going by a post off TGO (http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/). I've got every thing I think I need, but in this article he states that the PROM requires a change: Mag VSS at 0x18 b6 for $8D PROMS. I haven't seen this listed in the prom editor on Tuner Pro RT v4.12. How do I get this changed?

Post by **Mangus** » Sun Dec 18, 2005 5:17 pm

You might try a different XDF file. Craig's site (www.moates.net) has another $8D XDF file. Look or it in the file manager at his site. Perhaps that has it?

89gta5.7tpi · Post by **89gta5.7tpi** » Wed Jan 04, 2006 7:42 pm

After a few hours of reading over at TGO and finally asking for help, I found out that even though 89 gta's have a magnetic speed sensor like the 91/92's, they still run the pulse signal through an inline buffer which more or less converts the magnetic vss signal into an optical type signal, so the AUJP bin. I was using had to have this changed (magnetic vss to optical vss) so that the ecm would operate properly without showing an error 24(speed sensor error).

The change in TunerPro RT v4.12 using Super_8dm2.ecu to view the AUJP bin. is a simple switching off of "Switch 18" bit 6 (the vss switch). This is done by unchecking the checked box. Now my car runs fine with no error codes