ECM code mystery

[Santop]

Got 2000 5.7 plus mpi ,330 hp with no codes given but motet goes into power reduction at 2000 rpm any ideas ?

 

[makomark]

Are you Sure it is going into power reduction mode? Inadequate fuel pressure will cause a similar behavior.

If it is going into power reduction mode, a DTC does NOT have to be set but one or more of the ECM's inputs has crossed a threshold. You need to get the scan tool out and measure the inputs the ECM sees. As an example, if the coolant temp sensor reads 'higher than reality" but is within the "expected range", PR mode could be induced. No DTC is set because the sensor is within the expected window....

Not hard, but you need to know how the ECM operates and the right tools to get the correct info