2011 r60 sall4, 6spd

Been trying to run this thing down for a week now, but made some progress tonight ruling some things out.

TLDR: battery is ~3 months old. No issues at all with starting. Then one day, she started acting like battery was dead. clicks when starts (like it's a dead battery). can't jump using neg batt terminal. CAN easily jump using engine block. And what I found tonight, i CAN "self jump" by connecting jumper cable between neg batt and engine block loop. to me it seems pretty obvious it's something between neg batt term and negative starter.


For my complete saga-

Due to ordering parts, having my daughter 50%, and finding more parts that needed to be ordered, it took me 3 weeks to swap out my turbo that ate itself. My Mistress has a new battery from early March, and i hadn't had it on a trickler charger during that 3 weeks.

First start attempt after getting her all back together after 3 weeks, started right up, like nothing! awesome!

The next day I took her out for some new turbo check out motoring. several stops/starts. no issues restarting. (and upgrading to the 41mm jcw turbo, catless DP, and noise generator deletes from stock are -definitely- noticable perrformance gains!)

The day after that, my mistress would not start. made clicking sounds typical with a dead battery. odb2 simple scanner was listing between 11.8-12V inbetween start attempts. put her on trickle charger for a few hours. still clicks. tried jumping her using termainls to terminals, wouldn't jump. reseated cables, finally jumped.

scoured NAM and the internet for ideas on where to look.

later that day, after driving for 30-45 min, no start again after a stop. tried jumping again. wouldn't start. changed jumpers so it went to engine block on mini for negative and.she.started.right.up. odb2 scanner showed varying 11.8-14.4v when driving home.

click-no-start again the following day a few times. was able to jump no prob when using engine block ground loop (next to PCV connection off intake) for neg.

put her on a trickle overnight. charger shows battery is full. clicks again when trying to start her.

today I took battery fully out, did the wiggle test on neg batt to chassis. real solid. no visible corrosion or rust anywhere.

disconnected IBS. click.

took airbox out, visually inspected starter connections. no corrosion rust that i can see. wiggle test seems solid. put everything back.

light bulb.

took jumper cables and connected neg batt to engine block loop. she started right up.

so it HAS to be something between neg starter cable and neg batt term, right?


to recap, here's what I've checked/done-
1. new battery 3mo ago, everything has been fine (also, it was registered with new battery specs)
2. no visible corrosion on battery terminals/cables, or on neg batt chassis connection, wiggle test solid on chassis connection
3. no visible corrosion on pos/neg cables on starter, wiggle test soild
4. disco'd IBS for a bit
5. can "self jump" by connecting jumper cable between batt neg term and engine block ground loop

based on everything so far, i feel-
1. battery is fine, no dead cell
2. alternator is fine
3. starter is fine
4. must be wiring, but all seems good from what i've been able to check.


next to interrogate is-
1. the engine ground strap (do manuals actually have this?)
2. wherever the neg cable off the starter connects to. with all my scouring, i haven't found anything (i could be using the wrong search terms) that can show me where the other side connects to. Can anyone point me towards danger?


After those two, i'll be out of things to look at, so I'd appreciate any other tips.

thanks!

 

annnnnnnnd the winner was (at least it seems so far....)
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loose engine ground strap. the one that bolts to the top motor mount. the strap was super loose. tightened her down, and started right up 🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️