buddy of mine has a 08 LMM, the dpf has been removed, quadzilla programer, 6in stacks. but something has gone wrong, it dosent through any codes, it just says ENGINE POWER REDUCED. the it wont go over 15mph. anyone got any ideas?
Could be any number of things. anything from the accelerator pedal to the ECM. Most likely there will be a dtc present with the reduced power message that will give more information as to what may be going on. You may only be able to retrieve the dtc with a Tech II.
I have seen changing the air filter to a new one from being plugged do reduced power. Also a water and junk plugged fuel filter did this to me from a slug of bad fuel.
A plugged DPF will do this if clean DPF is ignored or air filter change above happens.
An aftermarket intake or air filter may also put the MAF out of range and limp you.
Pull both batts and reset the computer to exit this mode. (For awhile)
mine did the same thing with my new intake so i pulled it off and it worked fine after the stock filter was put back on.it did throw a code for mafs. it only would do it if it was really cold or if there was a change in temp of around of 10 to 15 degrees. i noticed the lmm trucks are pritty finicky.