jluis
Member
- Messages
- 1,703
I continue my quest to figure out why my 3200 AC doesn’t start once it’s hot and i have managed to at least consistently reproduce the problem and rule out a few things.
Starting with the obvious, the throttle body is refurbished and that made no difference.
The car always starts well when cold and up to the coolant 90C temperature.
When I shutdown the engine the throttle body becomes quiet, turn the key again. Throttle body hums and I can start the car.
Now, once the coolant is past 90C if I shutdown the car and remove the key, the throttle body will continue humming for a minute or so. If I try to start the engine it just cranks without starting.
Digging a little bit on the electric schematic and fiddling with the control relays I figured out that the spark plug coils control relay is energized when cranking the engine under normal conditions but when it’s in this hot state it simply will not energize, hence the no start condition.
It feels like the ECU initiated the engine shutdown procedure but it’s waiting on something, that only happens once hot, to complete until it times out and during that minute or two, I cannot start the engine.
And since the ECU is directly powered by the battery, removing the key will not make it reboot.
Being an IT guy this sounds a lot like a software bug but if that was the case then a lot of people would have the same issue.
Is there anything I’m missing that could be fooling the ECU into thinking the engine is still running?
OBS reports 0 RPMs
Starting with the obvious, the throttle body is refurbished and that made no difference.
The car always starts well when cold and up to the coolant 90C temperature.
When I shutdown the engine the throttle body becomes quiet, turn the key again. Throttle body hums and I can start the car.
Now, once the coolant is past 90C if I shutdown the car and remove the key, the throttle body will continue humming for a minute or so. If I try to start the engine it just cranks without starting.
Digging a little bit on the electric schematic and fiddling with the control relays I figured out that the spark plug coils control relay is energized when cranking the engine under normal conditions but when it’s in this hot state it simply will not energize, hence the no start condition.
It feels like the ECU initiated the engine shutdown procedure but it’s waiting on something, that only happens once hot, to complete until it times out and during that minute or two, I cannot start the engine.
And since the ECU is directly powered by the battery, removing the key will not make it reboot.
Being an IT guy this sounds a lot like a software bug but if that was the case then a lot of people would have the same issue.
Is there anything I’m missing that could be fooling the ECU into thinking the engine is still running?
OBS reports 0 RPMs