Battery Q before trip - opinions wanted

I do find a number of people that were tuned have more issues and I think it's more a need to do a CASE relearn procedure for a tune setup that doesn't idle well.

In the myraid of potential issues for low voltagle is the idea that the non-volitle memory wipes then it loses some of the sensor ranges especially the spark time to crank angle and goes back to stock and wants to relearn the crank angle sensor map (CAS or CASE depending on the book you have).

anyway donkey dick cam -bad idle tuning - need to do a case relearn but it seems to keep dieing at idle or worse won't start back up after dieing. Well it must be a bad ECU.... No it was a shit flash but it ran fine for a while.

However the ECU replacement fixes it becasue one you also replaced or recharged the battery - reflashed the new ECU and while at it adjusted the idle. presto case relearn takes and by jove it's fixed. well it is but you might have done too much.

But they don't just die - they tend to be pretty well made but yes it is true all the electronics are senstive to undervolting. and it's true of all new cars since 01+ more modern cars watch this better, like the G8 for example is has battery protection circuts and watches battery state of charge (no a voltage value) and as such prevents some issue.

Napalm said:

I do find a number of people that were tuned have more issues and I think it's more a need to do a CASE relearn procedure for a tune setup that doesn't idle well.

In the myraid of potential issues for low voltagle is the idea that the non-volitle memory wipes then it loses some of the sensor ranges especially the spark time to crank angle and goes back to stock and wants to relearn the crank angle sensor map (CAS or CASE depending on the book you have).

anyway donkey dick cam -bad idle tuning - need to do a case relearn but it seems to keep dieing at idle or worse won't start back up after dieing. Well it must be a bad ECU.... No it was a shit flash but it ran fine for a while.

However the ECU replacement fixes it becasue one you also replaced or recharged the battery - reflashed the new ECU and while at it adjusted the idle. presto case relearn takes and by jove it's fixed. well it is but you might have done too much.

But they don't just die - they tend to be pretty well made but yes it is true all the electronics are senstive to undervolting. and it's true of all new cars since 01+ more modern cars watch this better, like the G8 for example is has battery protection circuts and watches battery state of charge (no a voltage value) and as such prevents some issue.

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you sound a little confused, too. the whole idea of non-volatile memory is that it doesn't lose data when voltage is removed. you are confusing it with volatile memory. non-volatile is like an eeprom, for instance. volatile is ram. unplug the ECM completely, it doesn't lose the information stored in non-volatile memory, such as the OS and calibration.

ECM's are designed to be fairly robust and operate in a range of conditions, including voltage. they include types of fault protection. i've seen cheap simple electronics burn up because of low-voltage conditions, but i doubt it will happen with an ECM. i've had enough cars with very low or dead batteries and never had a faulty ECM because of it.

the interesting thing is... just took a peak at the E40 calibration file... injector offset vs battery voltage vs kpa vac. lowest voltage value in the table is 4.5V. it's also got values up into the 20's, and this example doesn't mean that either very high or very low situation is good.... but it does indicate that the designers took a wide range of system voltage into account. the ECM is going to try to keep the engine running in a variety of system voltage situations. it will also try to run in as low a voltage as possible until it just doesn't have the power to.

a dead battery is under 12 volts with no load on it, just for reference. if your battery voltage is under 9 with no draw, you've got some dead cells or something really bad going on. no charging is going to bring that POS back to life.

there's far more danger just killing your battery without having a tender than killing your ECM.

Nothubertjfarnsworth said:

any ecm shouldn't be flashed with a low battery or an under or over voltage condition.

and low voltage causes weird issues, already stated. get the system voltage back where it belongs and clear the faults. common issue, and ecm's aren't taking craps left and right.

anyway, cool fear mongering story bro. so when your e40 ends up failing anyway and spits a checksum error in your face, you'll come up with some other story. maybe ball lightning crawled up your tailpipe. you'll be telling us to cram aluminium foil where the sun doesn't shine so our ECM's won't fail. the p59 in my 04 will still be kicking it.

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Well you asked for it, so here’s some real fearmongering bruh.

I was driving down the road when the original ECM took a dump and the engine just quit running. That’s what can happen when the ECM pukes its non- volatile memory with no warning. Lucky me I had the Aeroforce Interceptor to tell me it was a ECM checksum error. The ignition switch wouldn’t even activate the starter until after it sat for a few minutes.

I’ve owned a lot of vehicles but this one takes the prize for the most fucked up electronics. The GM engineers did a wonderful job with the BCM wiring harness too, but I pulled the glove box out and wrapped it while it was still under warranty. To be fair the crappy AC Delco ECM probably wouldn’t have died at 56k mikes if I hadn’t been screwing around with two defective Optima yellow top batteries, the kind that you don’t check the electrolyte because it’s AGM.

Now back to the OP’s original question . If you can’t tell if a lead acid battery is good or bad get it tested by someone who can.

HMBLGOAT said:

Guess I’ll ask, why are you driving the goat 4,000 miles anyway?
That alone could be considered balsy

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So...feel I owe you all a reply.
4,033 miles, in the G8 GT I bought from former coworker, that I had driven a few wks after he bought it new. It was a lot more better trip car, what with it having a Trunk and all, than either GTO would have been - ride quality a lot better overall. Remember when I 1st drove it, I thought it was 'milder' than my GTO, even tho a bit more HP from the LS2-adjacent motor. And my bud of the same name, who I used to take to lunch in my Fiero then later in the GTO, is very picky, so I knew everything was well taken care of. He even spent the extra $$$ on a GM replacement windshield.

L A to Henderson to Claim Jumper's for white pizza (xlnt), then to St George UT to Zion Natl Park, then to Panguitch for Bryce Canyon, to Moab for Arches but stopping at Capitol Reef along the way, since we had our Parks pass. Then to Grand Junction & the Colorado Natl Monument since nearby (and since the wife said I don't want to go to Colo, it became a must see state). N to Rawlins WY, because too far to Jackson / Hole in one day. Along WY driving day picked up a 3" T25 screw in RR tire - not LF as shown (or checked by me when I looked at ALL THREE other tires when TPS warning 1st showed up 😒) took big 5 5 1/2 hrs to fix it despite being there 5 min after they opened the next morning - consistently 5? Nothing like pumping up a tire near a vaguely interested pronghorn antelope, or while seeing the sun set over the Tetons for the 1st time.
3 days in Yellowstone, followed by a few hrs to Bozeman, down the 191 to the Cafe of the same name in Big Sky (not at All like the tv show of the same name btw), Idaho which I don't recommend, don't mean to offend but least fav of the 8 states we went thru, then to friend's near Reno who I met when he bought a 66 GTO from me thru an ad I didn't place or even see in 1989?. After a day off from driving, to my cousin's in Los Altos, which included a brief drive of her 94 Caddy w/72K on it , very much the pristine little old (87) lady car. Then back here to thankfully no Memorial Day traffic jams - besides, had them all up near the Bay area on the 101 - which we took After I found out that the Coast Highway was closed in 3 places thru Big Sur (any one would have done) Would have been interesting to see how the G8 would have gone thru there
Ironically, charging the GTO batt as we speak, as it was One: % charged. quickly up to Six, but seems stalled at 44%

G8 got 25.8? mpg at 45ish mph avg - on Regular, that still impresses me - as stops in the Parks, and a bit of local driving around. Other than tire screw, one bogus ABS warning in Panguitch (btw - if you're ever going to Bryce, eat at Kenny Ray's or Cowboy Smokehouse) after dinner which I fretted about for 8 blocks back to the motel & til I woke up the next day to frost on the roof, a full master cylinder, and No problems. used about a 1/2 qt of oil, and no anti frz near as I could tell. Highest temp on the trip was a bit over 80 I think, and highest altitude was 9600 ft, on an unnamed random pass in Utah. Did not expect most of the trip to be spent over 6000 ft.

Not really 'ballsy', but an epic trip of the kind we only too Once, driving out across the country in my 66 GTO as the 1984 Olympics were going on