graemewl

My 2004 ES300 stalled at traffic lights twice yesterday . No other weird symptoms, no check engine light, it just idled normally for 20-30 seconds or so, then stalled. It took a little cranking to get it started, but then ran fine until later in the day when it did the same.
I'm at a loss where to even start diagnosing this.
Any help or suggestions before I have to take it to the dealer would be most appreciated.
Thanks,
Graeme

steviej

iTrader: (1)

for any reason, just prior to the onset of the stalling, did you disconnect the battery and reconnect it?

steviej

graemewl

No, I have never had to touch the battery (yet).
I have also noticed a very high idle when cold and a little hunting during idle once warm. I'm suspecting a vacuum leak right now. Time to break out the starter fluid...

Thanks,
Graeme

Lexucan

Check your coolant temperature sensor. If it is sending false readings to the ECU, it can cause the sort of idling problem you are experiencing.

steviej

iTrader: (1)

sounds like the idle air control valve is a little dirty, too.

graemewl

Update:
I went around the engine bay and re-seated all of the vacuum lines I could find. Car idled a bit rough after that, then after a nice 40mile round trip on the freeway has settled down and is running like it was before the stalling incident. I can only surmise that one of the vacuum lines was a little loose and the ECU was trying furiously to compensate for the extra air. Once I sealed the leak, it took a little while for the system to purge the bad sensor readings.

Fingers crossed that I have actually fixed the problem.

Graeme