OK I have searched and tried all so please don't blast me! My daughters cobalt is the dreaded 05. Would stutter now and then from the day I bought it (rpm would stutter, gauges would fall) but only for a second then good to go. Her first car so I said 'drive the wheels off it.' Got to the Eng. Pwr reduced/disabled messages and would die. Key off, 10 seconds, crank and go. Left car sitting one month during cold weather. Now car will start and within 5 seconds 'eng pwr reduced/engine disabled message.

I have;

Ran enough grounds to lightning proof a warehouse. Replaced MAF, MAP, crank sensors, ignition control module, plugs, and coil pack. Traced every wire I can find for possible shorts. No dice.

The only things I haven't replaced are the throttle body itself and the evap solenoid. I don't think this model has a secondary air injection pump. I can't find it anyway. Did switch the throttle body onto a running cobalt an it worked fine.

ANY ideas?? This little car runs amazing when it does run an I don't want to scrap it but I also don't want to keep beating my head and wallet against this wall

 

It throws a dozen codes but since the sitting I've not ran them. Ordered a little scanner so I'll post those codes when I have them. May be note worthy that holding the + and - battery cable ends together (unhooked of course) will no longer reset the computers/eliminate check engine light

 

most power reduced messages relate to the drive by wire throttle system...throttle body or accelerator pedal position sensor.

see what the codes are and diagnose from there. probably will need a throttle body.