[06aeroSS]

I was trying to find some info on the v6 and came across this in some Saab literature on the 2.8 v6 engine launch.

The engine controller provides a limp-home mode for ignition timing, in the event either the crank or cam sensor fails. It will continue to control timing based on data from the functioning sensor, and advise the driver with a warning light. It also provides coolant loss protection, which allows the V6 Turbo to operate safely at reduced power, even after there has been a total loss of engine coolant, so the driver can reach a secure location.

How can this be? Has this ever happened to anyone?

 

[ChrisAero]

The loss of either a cam or crank sensor can be made up by the other sensor to allow the engine to keep running. Items like VVT will be disabled. For the coolant loss condition, GM developed an algorithm originally for the Northstar V8 that allows continued operation for a short time. When it is determined that a catastrophic loss of coolant has occurred, the engine will shut down cylinders in an alternating odd-even manner, as well as limit total throughput via electronic throttle control. When the cylinders are shut down they continue to pump air, effectively air cooling. If the total output is limited in conjunction with the air cooling effect, the engine can maintain temperature control long enough for the driver to get to a service station. The function is meant to avoid stranding someone at the side of the road

 

[06aeroSS]

Cool. I never knew that. For once I guess we can be thankful GM had their hands in the cookie jar.

 

[Pilgrim]

Anyone who trusts such a system is asking for a lot. The only safe thing to do in such a case is to shut it down NOW and either have it towed in or fix the leak.

 

[theSandySaab]

My Saab garage/workshop had a red 2008 V6 Aero Hirsch'd for rent that someone drove for over 200 km with the engine light on due to low/lack of coolant. That engine seized up! Renter was asked to pay but somewhere along the line they found an insurance to cover most of it.
Still, only an [email protected] (or in a desperate situation) would continue to drive without trying to fix the coolant issue...

 

[06aeroSS]

Anyone who trusts such a system is asking for a lot. The only safe thing to do in such a case is to shut it down NOW and either have it towed in or fix the leak.

Yeah I have to agree there. I was just completely unaware that this was part of the design. Never heard of it in any car.