by David Gentleman » Sat Jan 07, 2006 1:17 pm
Units such as the Dastek on 'normal cars' tap into the throttle pot feed to monitor load, map sensor and TDC signal, so the timing can be modified.
The GTA doesnt have a 5v pot which can be used (as it is a digital switched affair), so that rules out most part throttle and cruising mapping... The air and knock sensor inputs have a multiplier which retards and richens the ignition and mixture too much for safety (this is why the GTA's get low RR readings when hot), and the Piggyback unit has no control over these readings.
So, if you try and shift all the ignition up to compensate, when the engine is not running 'so' hot, there will be too much ignition advance and most likely knock (which kicks in the original knock retard!)
Most places that fit piggyback chips are around £500 so its no even as if its a cheap mod to do initially..