Limiting the max RPM during cold start

[Azmio]

Hi everyone,

I came across the BMW M5 engine management system. It is kinda interesting how the ECU limits the maximum engine rev during cold start to 4000rpm only.

Anyway, I am looking for the possibility in using the ECU to limit the engine rpm during -30 C cold start.

My question is, at such a low temperature, how will the ECU know that the engine will be started at such a low temperature. Is it through the coolant water temperature sensor only, or there is other mean in knowing that the engine is about to be started at such a low temperature?

AO

 

[gregdachs]

It ultimately doesnt matter how cold ambient air is for the start, does it? What i mean by this is if the engine is hot already then the coolant temp is hot and it is no longer a cold start. Thus, the coolant sensor is all you would need. Unless, however, the coolant sensor cant see temperatures that low.

 

[Azmio]

Gregdach

Here is the situation, a grandma in Tempe Arizona uses 15W50 engine oil for her car. During very cold winter, she drives to Canada to visit her grandchildren. One freezing morning, she was in a hurry and was on full throttle to climb a steep hill right after she started the engine.

The question is, does the ECU know that the at -30 centigrade the 15W50 oil viscosity is bad? Will the ECU be able to stop bearing and piston seizure or excessive wear to the moving component from happening?

I would agree with you that the ambient air doesnt matter much if the cold temperature does not affect the coolant and oil. Unfortunately, the tests that we conducted in the cold chamber revealed that the ambient air really affected the coolant and oil. As a result, the moving components of the engine got really affected.