AEM 30-6620 Series 2 Plug & Play EMS - Manual (Page 5)

5) Troubleshooting an engine that will not start
a) Double-check all the basics first… engines need air, fuel, compression, and a
correctly-timed spark event. If any of these are lacking, we suggest checking simple
things first. Depending on the symptoms, it may be best to inspect fuses, sufficient
battery voltage, properly mated wiring connectors, spark using a timing light or by
removing the spark plug, wiring continuity tests, measure ECU pinout voltages,
replace recently-added or untested components with known-good spares. Check
that all EMS sensor inputs measure realistic temperature and/or pressure values.
b) If the EMS is not firing the coils or injectors at all, open the Start tab and look for the
‘Stat Sync’d’ channel to turn ON when cranking. This indicates that the EMS has
detected the expected cam and crank signals; if Stat Sync’d does not turn on,
monitor the Crank Tooth Period and T2PER channels which indicate the time
between pulses on the Crank and T2 (Cam) signals. Both of these channels should
respond when the engine is cranking, if either signal is not being detected or
measuring an incorrect number of pulses per engine cycle the EMS will not fire the
coils or injectors.
c) If the Engine Load changes when the throttle is pressed this usually indicates that
there is a problem with the MAP sensor wiring or software calibration (when the
EMS detects that the MAP Volts are above or below the min/max limits it will run in
a failsafe mode using the TPS-to-Load table to generate an artificial Engine Load
signal using the Throttle input). This may allow the engine to sputter or start but not
continue running properly.