Strange complete loss of power
 

This has happened 4 times in last 6 months. While accelerating, the engine will lose ALL power. It doesn't stall. The engine continues to run, but RPMs drop to an idle. Depressing the peddle does not increase RPMs. Like it's become disconnected. In gear or out of gear, car will roll to a stop. If I kill everything (turn off electrical) with the key and restarting it fixes the problem and everything seems normal. It's happened after the car has sat for an hour or more, it's also happened after running for a couple of hours...seems totally random. I've owned everything from a 68 Charger with a 383 to a 1641 VW bug and never seen anything like it.

'04 G35 coupe
Engine was "blown" and rebuilt by racing shop
rebuild has around 50k;

Any ideas?

Keep an OBD2 scanner in the car to check for codes next time this happens.

If it doesn't throw a code I'd suspect something is failing in the accelerator pedal switch. This car is "throttle-by-wire", the gas pedal is merely two inversed rheostat switches, one scales 1-5 volts, the other 5-1 volts. The ECM reads both and calculated throttle position then sends the voltage signal to the throttle body.

If something fails on both APP (accelerator pedal position) switches then the ECM won't thing there's something wrong, you just wanted not uave any throttle input.

Since it happens after the electronics are hot that makes me think APP but you need to scan for codes while the problem exists because it might be a hidden code which will not trigger the SES light.

That's what I was thinking....
 

I had a feeling it had something to do with the drive by wire system. What that system was, I had no idea. I did want to say, but I doubt it makes a difference, but you mentioned it....it happens not just when things warm up, but it's happened within minutes after starting and having sat for hours. So, hot and cold.

Getting a code wont be easy. I have I have a scanner, but so far it's occurred at I'll inopportune times...getting on freeway, making a u-turn, and morning traffic. One of these times I'll catch it happening while parked!

Thanks for your input!

Just make sure to not turn off the engine next time it happens, pull over if possible and pull codes immediately without turning off the engine.