03 G35 stalls while Driving

[916_03_gthree5]

While driving the car completely looses all power including electical. The electical and performance fluctuates; sone times it comes back on before going in a complete stall. Just started happening. No check engine or other idiot light on. Brought to dealer and since it is an intermittent problem and no codes from computer, they don't know. Any advice?

[TommyGunnZ33]

The only thing that comes to mind is a loose battery cable, hard to say without a code... Loose ground somewhere?

[RED_DET]

I second checking the battery terminals.

[tjrob2000]

I have similar symptoms with my '07 G35 Journey with the HR engine, but I'll elaborate a bit more and 916 can chime in if they've had the same.

Wife started car this morning and said it barely started. Tach was below 1000 rpm and fluctuating wildly. Slip, CEL, ABS, pretty much all lights were on.

Later I start the car and it starts normally. Take it for a drive (was going to Autozone to see if there are any pending codes) and after pulling into heavy traffic it starts bucking, slip, VDC, CEL, ABS, Brake lights are all on. Speedo drops to 0 at one point even though we are going 20mph. Initially after startup it would rev normally. At this point, after the stumbling occurred, it would barely make 3000 rpm. Searching I've done appears to lead to the Crank sensor or one/both cam sensors. I'm going to get it to a service shop tomorrow morning (hopefully), but thought I'd post here to see if anyone has other ideas.

[tjrob2000]

Update: shop diagnosis is the alternator not putting out consistent voltage so they are replacing the alternator tomorrow. We'll see if this is truly the fix since there were no codes.

[tjrob2000]

The shop installed the alternator yesterday morning and when they went to start the car they found the battery was at 5vdc, same as Thursday morning for me. Took the battery to autozone where they charged it and tested it giving it their seal of approval. Shop installed it (they continued with one of their batteries in the meantime) and all looks good. Checked the battery last night and it was sitting at 12.85vdc, much better than it was previously at 12.3. I'll keep monitoring it, but it looks like the regulator in the old alternator drained the battery.

[tjrob2000]

Update: Car has been running normally for last two weeks so the alternator was the problem.