Car is Myvi 2005. Had about 300,000KM on this old thing.
Now having problem - engine died at random during stop at traffic light. Usually when A/C is on and radio is turned on.
All radio settings got reset once the engine died.

No check engine light.
Repairs done: changed fuel pump, cleaned throttle body, new spark plugs.

My usual mechanic under the tree stumped on this curious problem. Bit of googling says that it might have something to do with radio but it was a really old thread, so I thought that this might be a common problem that I didn't know before.

Many thanks.

EDIT: checked alternator and battery. Normal.

Now sometimes the engine died when turning on the headlights lol. Happens when stuck in jam.

This post has been edited by Steponlego: Jul 7 2022, 09:59 PM

Not done yet. How does a bad battery can cause this problem?

I think last time I replace the battery was back in 2020. Amaron brand.

Makes sense.

Come to think of it, electrical stuff isn't exactly the mechanic strong suit. Never saw him hold an OBD tool. I think I have reason to doubt his word saying that the battery and alternator is good.

Where to do this test? Battery shop?

about 700RPM, normal for the engine as stated under the hood.

battery and alternator is okay.

looks like have to send few days to workshop for thorough wiring checking.

this myvi is actually my brother's. said that he went to a battery shop yesterday and they said charging capacity and whatnot is at almost 100%.

to be honest, this car is not really well taken care of, just a beater car for commuting to work. it's full of literal garbage inside. i wouldn't be surprised if this problem is caused by cockroach that bite into some of the wiring or got shorted in between the electronics. only reason i even bothered to open a thread is because i don't want him borrowing my car because the myvi keep giving problems.

if you mean the 5 years old battery, that's on a 2007 Persona. that one doesn't give any problem for the time being.

i do notice that the RPM slightly increased and engine revved and make more noise when headlights are turned on.

oh and the car uses Exora's A/C compressor, which definitely changed the load of the engine because the car makes lousy acceleration and noticeably a lot more noisy when it's on. the A/C workshop said it's totally okay to use larger compressor but I don't really trust it.

want to send to workshop but they had too much car today. oh well.

Went to new workshop. They looked into the problem, test drive to replicate, but no success. Everything working normally. No trouble code was found. Throttle body works fine. Electrical is fine. They suspected the idler valve, but can't be sure because it looks like its moving normally.

They put some grounding wire on battery and then ask to try few days until it happen again. Zero charge for the service.

They didn't manage to find the problem. It simply doesn't happen again and everyone doesn't know why. Workshop put an extra grounding wire on the battery and somehow it was fixed. The grounding wires are well known snake oil for old cars, but somehow it worked.

They take like random wire from their junk bin, then connect it from the battery negative to random point on the engine bay. Wanted to pay them for their trouble but they won't take it haha.