Piggyback ECU

Newer piggy backs like the e-manage ultimate can control your ignition timing separately from your airflow readings, but there are still catches. You are able to change ignition timing maps but the e-manage simply changes the output signal the ecu sends to the coils. The problem is the ignition timing numbers are not always consistent with the changes you make to the load sensor, whether its your map, or maf sensor. So you are guessing the timing numbers. The stock ecu also has multiple maps it can run for different conditions so you are not always consistent with the tune.