[b3lha]

Originally Posted by Hocrest

I found this thread over at Legacy Central, where they discuss getting into the ECU on Legacy's. I'm not sure if any of it would be useful to those trying to get into the SVX ECU, but I thought I'd post it for your info.

Thanks Hocrest,

I've seen that thread before, and yes it is relevant. Thanks for posting it.

Vikash made some comments on Legacy Central about the scaling formulas being wrong in the vwrx software. I had a look at his software and there are some differences. I can't say who is right and who is wrong.

For example, suppose the ECU stores the TPS voltage value as F8 hex.
Kevin's vwrx software calculates (N * 5) / 256 and reports 4.84 volts
Vikash's legacy software calculates N / 50 and reports 4.96 volts

At some point I'll check with a voltmeter and see which one is correct. Assuming my cheapo meter can measure accurately to 0.01v.

There are other examples too. If you look back at the screenshot of the vwrx software, you will see that the knock correction is reported as 128 degrees. According to Vikash's source code, the number 128 actually corresponds to 0 degrees retard. It counts up in quarter degree increments. 129 is 0.25 degrees retard, 130 is 0.5 degrees, 131 is 0.75 degrees etc. Presumably this value is subtracted from the ignition advance value somewhere in the ECU code.

I don't want to say that one software is better than the other, just to highlight that the values reported by either one may not be spot on.