You may already know about this, but you have to disable the checksum. There are threads with posts by various folks that reference this, but there isn't a glaringly conspicuous thread dedicated to it (at least that I found). So I'm hoping this helps other people.

I found this out by essentially by accident during a search... and it found Moates' website.

https://shop.moates.net/pages/obd1-gm-checksum-disable

Here's the thing... for years when running the Ostrich 2,0, occasionally when I'd upload a bin to the Ostrich, the ECM would go into hard fault mode with the SES light coming on and the engine running really rough, in what appeared to be limp mode. I'd have to pull over, shut the engine off, clear the ECM memory, and then re-start the car. I wired the ECM battery power to a rocker switch in the glove box for this very reason, so I could clear the memory without having to actually pull the plug out of the ECM. I had always attributed this to a random software glitch and didn't think much more about it.

There were also cases where I’d make a small change to something and the change to engine performance (good or bad) was a bit out of proportion to what I did. So there was always this head-scratching behavior that just seemed like random software glitches.

On the average, the car ran great... but I'd get these periods of odd behavior and occasional inconsistent operation, after I'd make a change. But I always attributed to random software glitches.

The other day I started searching around for possible causes of this and then discovered the notification by Moates.

But then when I saw this info about the checksum vs emulation, I started wondering if these anomalies was this issue with the checksum and the Ostrich. Like the ECM is going into some “soft” limp mode or some weird mode of operation where it’s ending up with reduced performance or something.

So I did the checksum change and have been driving the car quite a bit lately and I’ll be damned if it didn’t solve that problem. The hard fault mode thing is gone and I’m getting very consistent operation... VERY consistent.

Basically in Tunerpro, change the checksum to AA. My checksum for 8D is in fact 8D... so I just changed it to AA.

Note that if you're running Tunercat, when you open the file you'll get a pop up window saying that it detected an incorrect checksum. You just click OK and ignore it... it'll load the bin just fine. Tunercat RT also has no issues uploading the file to the Ostrich either.

The only thing is if you download the Ostrich contents using Tunercat RT and then save it, TC RT will reset the checksum back to the factory value. You'll have to disable it again.

Tunerpro doesn't do this. I may contact Tunercat to see if they can change that.

Hope this helps other folks!

 

Great info

 

Yanno when I don’t quite understand things but know that it works, I won’t delve into any further. Anyhoo, to disable the checksum, you change the mask id to AA. I.e. 6E to AA, 8D to AA etc. btw have you pressed F2 while having any of the parameters selected in the tree on the left hand side? If written well by our pioneers, it shares a wealth of information.

 

Oh man, have I ever...

In fact there is no freaking way I would have gotten my Miniram to where it without that. The S_AUJP series of files, Tunerpro with all of it's commented parameters, scalars and tables, Moates' Ostrich II emulator. Absolutely no way.

 

The only checksum I see is "0" zero?
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If you're looking at the 6E xdf, look at the Mask ID parameter.

 

Thank you very much @ULTM8Z

What is the $32B equivalent? and does it need to be manipulated? I see no mask ID in $32B.
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Ill have to look later...

 

The 32B xdf from Tunerpro.net didn't have the Mask ID (or checksum). But I found a different 32B (for a V6) on Gearhead EFI that had the Mask ID parameter. So I copied the parameter over to the one from Tunerpro.net. It should be the same hex location in the bin file.

When I open a few 87 Vette bins with it, I see the Mask ID as 32 (which it should be). So it looks correct. The checksum is always the mask ID... 8D, 6E, 32B, etc...

You can try this xdf and see what happens (use at your own risk of course!). Simply set the parameter to AA to disable it.

I can't post it here.... if you email me at ultm8z@yahoo.com I'll email it to you.

 

Thanks for all the work.

Is evap PURGE in there anywhere ?????