Hello fellas. I could use some guidance using the Hex editor in TPRT. I'm working on a 1989 GTA that we converted from MAF to SD (165 to 730 ECM) and now the VSS input is non-existent in the datalog. Most of you have probably seen the instructions, but they say, "requires PROM change: MAG VSS at 0x18 b6 for $8D PROM". Unfortunately for me, I have no clue how to make this change; never worked with the Hex editor before.

The car is a 1989 GTA with a newly rebuilt 383 HSR, 230/236 cam, hooker 2055's and a T56. It's running but it's really down on power and sluggish. Every data point in the log is pulling 6+ degrees SA right now and I'm not sure if it's because of the VSS or not. I've been pulling timing and fuel, but want to eliminate the VSS as a problem. I'm using TPRT with Moates Ostrich 2.0 to tune the AXCN bin with matching XDF and ADX files. I was hoping the XDF would have had this field defined, but it doesn't. Any help I could get with the Hex editor is very much appreciated. Thanks in advance!

 

Vss optical is pin c6 on the 730. It’s just a flag change from
magnetic pulse.

 

 

Make sure you disable the checksum if you're using the Ostrich. Need to change it from 8D to AA.

https://www.thirdgen.org/forums/diy-...-checksum.html

I don't think the VSS has anything to do with your timing.

That said, I would probably switch over to S_AUJP as a starting point with a setup like that.

 

No need for a hex editor.

i don’t know what Youre looking at but if x18 means x018 address bit 6 you can simply create a new flag in tuner pro by right clicking and adding one at address x018 bit 6 and when you open it check or uncheck it.