Car allergic to vanilla ice cream (2000)

"If the person's different activities _actually_ resulted in a significant difference of time the car has been sitting, it's likely the owner themselves would be able to easily deduce what could really be the issue."

Oh, I wouldn't even remotely bet on that. Even in my professional sphere of programming I've been caught by what I call "cognitively available" theories of what the problem is that turn out to be entirely wrong in the end, because the real problem is something I wasn't even remotely considering before hand, and possibly even would have dismissed if it had crossed my mind.

If you don't even know what "vapor lock" is, and I assure you this will describe the majority of car owners, why would you think "time in store" is the difference?

What is cognitively available to this person is that they buy different sorts of ice cream and that causes the problem. It puts the spotlight of cognition on that factor to the exclusion of other things. Even the engineer trying to solve the problem was probably slowed in his investigation by such an appealingly available issue being proposed first; again, I've certainly experienced this in my own professional sphere where someone proposes some explanation that ultimately turned out to be completely spurious, and it takes actual effort to get both myself and my team off of that line of thought.

> Moral of the story: even insane-looking problems are sometimes real.

To me the moral of the story (and my experience) is: user's problems are usually real, but don't trust their ability to diagnose the actual cause.

My wife's car right now is low on windshield wiper fluid. It warns us at a particular spot while we are driving. Not a particular distance from home, a specific geolocation. First thoughts were that it was the amount of time as she went to something and came back. But it does the on screen and audible warning at that location every time, no matter what was driven before that, whether it was 5 minutes, 5 miles, an hour, or 60 miles. The only additional clue is that exact same spot is a dead zone for most phones/carriers.

We got the wiper fluid filled, so the mystery is in remission, but I'm wondering if all warnings will pop up right then. I'm guessing it has something to do with the telemetry of the car being nudged in that spot, waking up and saying something.

i learned that these things typically are grounding issues. it usually came down to a single source of ground being a loose connection which is why it was intermittent. as a personal anecdote to this, as a first car as a teenager, i drove a GM/Chevy S-10 that one day started to have issues where all of the gauges on the dash would just go crazy and the lights would go on and off, and then suddenly just start working again. after taking it to the shop my dad recommended, a mechanic walked out to greet me. after i told him the symptoms, he stepped back to look at the truck model, asked me to confirm the year model. he promptly opened the driver side door, reached under the dash, located a specific screw, hand tightened it as a test, and everything worked. he came back with a screw driver to properly tighten in before sending me on my way free of charge. he told me that specific model was notorious for the screw holding the ground wire to come loose. it would cost him more in time to write up a sales slip to charge me.

I have a 2009 Mercedes SLK that had the same symptom. It was absolutely fine 99.9% of the time, but one time in a thousand it wouldn't even try to start. No clicks, no indication that it even knew I was in there turning the key. Just dead. And then seven or eight hours later... it would start fine, as if nothing ever happened. Couldn't correlate it to anything.

Had it towed to a service center a few times when this happened. Every time, by the time they got around to trying it (a few hours later)... it would start fine, with nothing to diagnose.

Then, it was 99% of the time it was fine. I was with a group of folks car-camping off road to fly a human powered airplane for a couple days, and... no start. Finally started -- with no sign of any problems -- around noon the next day, and I high-tailed it out of there a day before the rest of the group, because getting stuck there /after/ the rest of the group would have started pushing my comfort level. So at this point it's actually interfering with my life.

I've tried all the usual stochastic troubleshooting (swapping out fuses, light to moderate percussive maintenance, alternate keys) and nothing. Finally it fails to start in my driveway, and I get it towed to an independent mechanic. It's short tow, and it fails to start when it gets there! So now he's seen the problem, and is as puzzled as I am. Of course, when he tries again the next morning, it starts fine.

He proposes two possible fixes: replacing some ECU module, or replacing the fuse box itself (under the theory that it's the connector or connection into the bottom of the fuse box that is having some moisture ingress or intermittent connection). Of course whatever we choose, I won't know if it was right or not until the next time I'm stuck. The ECU is multiple thousands of dollars, and the fuse box is This was six or seven years ago, and that car is still my main and only car. Hasn't had a single mechanical issue since swapping out that fuse box. A good independent mechanic and a good guess!