[b3lha]

Originally Posted by svxistentialist

Two questions occur; in the JDM car, we are accustomed to thinking the ECU has software that "restricts" the top speed to 180 kms/h. Would it be safe to presume the TCU, which handles the speed signal before the speedo, has no role in this? In other words, using a European ECU with a Japanese TCU should not impose the Japanese speed limit to the arrangement?

The speed limiter is in the ECU, I have proved this by bypassing it on 4 JDM SVXes. Read this thread for information about how the speed signals differ between JDM and Euro/Aussie cars. Harvey, JJ, Tony and I figured it all out: http://www.subaru-svx.net/forum/showthread.php?t=31506

The other question is similar; the JDM ECU is tuned to use top grade petrol, while the Eu models are tuned to handle our rubbish. Would the JDM TCU be tuned in any way to suit the better grade petrol they enjoy? I presume not?

I've noticed that my cars run MUCH better on 98 octane than 95, so the ECU may have some tuning for higher octane petrol. The TCU wouldn't care about that. It just has to measure a few input signals, run a little algorithm and set the output signals to select the correct gear.