Quote:
Originally Posted by sflgator
...so they ECU thinks it's running normally.  |
I could only see how this could be true when the piggyback signals are within normal ranges. Presumably, the piggyback only works by counting on the ECU to compensate correctly. The ECU still knows the exact parameters for boost pressure, fuel delivery rate, and timing values, for example.
However, boost spikes are a normal occurance w/out the piggyback. And presumably, the ECU routinely deals with these events appropriately w/out raising a red flag. But it is conceivable that the ECU could maintain a running average of boost level and qualify some range to be out of spec. The running average could be over several seconds, which would disqualify a spike and indicate an abnormal regulation.