Wierd problem when P&G used extensively - '01 Civic
 

So, as I use pulse and glide more and more, an odd problem is cropping up. One stretch of my morning commute allows me to P&G a lot, to where the engine is off maybe 2/3 of the drive. Near the end of this leg, my car will randomly lose all power, no radio, no dash lights, no speedometer, ultragauge cuts out. If I put it in gear and let the clutch out, the engine will turn over... and after a second or two, fire up. After that, it will run just fine other than sometimes needing to relearn its idle.

Any ideas what is going on?

No loose wires, and I have found nothing obviously wrong. I never see this while driving "normally". I have a theory, but I wanted to fish for other ideas first.

battery voltage getting too low?

Second that.
My Insight will shut the engine off when stopped (Auto-Stop) but restarts within 20 seconds or so, where it should last much longer.
I used to key off at the lights to prolong the autostop.

My new UG now shows the real reason why the engine restarts: the voltage drops below 11.6 volt, and continues to drop if I keep the engine off for too long (with lights and radio on)...

I 3rd that. A general rule of thumb with battery voltages (car is completely off with no load on the battery at all):

Full charge 100% is 12.7volts
90% is 12.6volts
80% is 12.5volts
70% is 12.4volts
60% is 12.3volts
50% is 12.2volts
40% is 12.1volts
30% is 12.0volts
20% is 11.9volts
10% is 11.8volts
0% is 11.7volts

Check your battery voltages with a volt meter with the engine off to see where the battery voltage is at.

This is also why if you us heavy p&g...you should also switch your battery out with a deep cycle battery

Put up battery voltage as an ultragauge gauge and see how low you're draining that poor little battery. :)

Yeah, sounds like you're getting low on battery voltage. When you really do intensive EOC P&G the issue becomes that the alternator only runs when the engine's on and the battery draw during the glide is greater than the battery charge during the pulse. This is particularly true this time of year (for those of us in the northern hemisphere). The days get shorter, so you need to drive more in the dark. That means more current draw for the lights. Colder temps also mean more current draw whenever you need to use the starter to crank the engine over.

I ran into this issue just a little last winter, and it's starting to happen again to me. Currently I average % for the engine running is about 15%. For me, it'll happen when I do a cranking start--the engine may crank a little slow, then when it starts up the ECM resets: trip meter, hr meter, FE meter, etc. all just reset. Occassionally, I've also seen the odometer lose a couple miles.

I believe Pale has also run into this issue (at least with his last car).

Here are some optons:
1) Do whatever you can to avoid cranking starts (starter use). This can be done by managing lights better , scubbing speed off and then bump starting, etc.
2) Do whatever you can to reduce current draw. Leave the radio off, HVAC blower off, etc.
3) Start using a trickle charger at least occassionally to restore the charge back up.

This is what i do every night when i get home. Plus with the battery topped off...it means a little less draw on the alternator...means slightly better mpg.

Yes I have had to deal with this.

LED taillights, markers, license plate.
Eco halogen headlights (10% lower power). No HID's because I'm not a jerk.
DRL disabled, but I use my LED marker lights instead for visibility.
Trickle charger overnight when it's low, but...

I just ordered a solar panel to charge it while I'm at work every day. I'll be sure to report back when I have some time with it.

I had word that Santa's Chinese elfs are carpenting a fine small solar panel for the December festivities to aid my poor battery. If it makes December. We'll see.

And only now I see PaleMelanesians post, and see what I forgot to mention; I got LED license, dome, door entry, map, city & fog lights and HIDs for the low beams since January. The rears are LED as OEM. There's not that much load on my battery.

No trickle charge, but neither the CVT nor my commute allow for much EOC P&G, so I get less chances to drain the battery. Got about 50% engine load (says UG) on even the fairest of steady 50 mph highway (long) drafts.

Well, my theory was that I was draining down the battery and at a certain voltage, it just cuts all power. By everyone's responses, I'd say my theory is confirmed.

I very rarely start with the key, it's almost always bump starts. I typically lead the headlights off as much as possible, but it is getting darker. I have been running with just the parking lights, I may have to look into LED bulbs as Pale suggested.

The beginning and end of my commute both have much less opportunity for P&G, so the battery tends to get more charge built up then. It's only the middle leg that I find I have trouble with it.