Mario

G'day,
I've never heard of "overboosting" switch, what is it?
Anyway here:






I would ensure that earthing circuit are correct. Y61 is notorious for bad earths, indeed I recommend running extra earth cable between chassis and body and en
gine and chassis.
Regards
 

G'day,
Chances are that ECU from the wreckers will not be very useful to you without immobilizer recoding. However hold on to that ECU cause you can send (unless you are close to mid coast of NSW) it to have it re-maped and as a part of it they can disable immobilizer so not only you gain extra ponies but keep your original ECU as well. Much better option then diesel "piggy back" dodgy chip.
As far as that "overboosting switch" there is no such thing as a switch.... What happens is that ECU monitors MAF output and correlates it to TPS position and RPM and if values are too high it will derate until you release pedal and re-apply which resets the limp process. That is what happens not the overboosting indeed ECU seems to ignore boost values in regards of this function on Series 1, 2, and 3. From Series 4 onwards there is mapping for boost as well incorporated in ECU fuel mapping and it will limp if you exceed 18 psi but still MAF, RPM and TPS% is considered.
Regards