2.7 Turbo 4 Fan Club

[customboss]

2 hours ago, silveradosid said:

my 2020 has started throwing code p2c9b for the turbo. it only does it if the temperature is below freezing.first start of the day it triggers the code, i can clear the code and it is fine for the day. any ideas

Bypass circuit for warming be my guess. 

[silveradosid]

the code implies that it is taking to much power to do the test at cold start. i have taken the rod off and the wastegate moves freely, could this be a bad actuator

[TheRiver]

Bump to top.................

 

How do these engines do in weather like this.....................this was low overnight.

 

this is current at 1:00pm....

[newdude]

24 minutes ago, TheRiver said:

Bump to top.................

 

How do these engines do in weather like this.....................this was low overnight.

 

 

this is current at 1:00pm....

 

 

 

Never saw it that cold but mine did just fine in single digits with sub-zero wind chill. 

 

They heat up better than a regular 4 cylinder in a little car since they have that active thermal management.  It can go as far as bypassing the radiator and oil cooler to allow for as much cabin heating if the heat is on.  

 

Cooling Cycle

Coolant flows from the electric water pump outlet and into the engine circuit and turbocharger cooling circuit. It also provides cooled coolant flow from the radiator to the engine coolant flow control valve to be used as necessary to manage transmission and engine oil temperature. In the engine, the coolant flow direction and volume is controlled by the engine coolant flow control valve and the block control valve to provide necessary flow for optimal engine block, cylinder head, and exhaust manifold cooling. The engine coolant flow control valve can also provide the transmission and engine oil circuits warmed coolant from the engine to optimize the oil temperatures. Excess heat is removed from the coolant in the radiator and the cooled coolant returns to the electric water pump.

 

Mode 1 (Low Flow):

Flow Diagram - Mode 1

 

 

 

 

(1)	Surge Tank
(2)	Turbocharger
(3)	Auxiliary Heater Core (If Equipped)
(4)	Heater Core
(5)	Radiator
(6)	Condenser
(7)	Main Rotary Valve
(8)	Engine Outlet Coolant Temperature Sensor
(9)	Engine Cylinder Head Coolant Temperature Sensor
(10)	Integrated Exhaust Manifold
(11)	Cylinder Head
(12)	Engine Block
(13)	Engine Block Heater
(14)	Engine Block Coolant Temperature Sensor
(15)	Block Rotary Valve
(16)	Engine Oil Heat Exchanger
(17)	Transmission Oil Heat Exchanger
(18)	Radiator Outlet Coolant Temperature Sensor
(19)	Electric Water Pump
(20)	Engine Inlet Coolant Temperature Sensor
(a)	Valve Port A
(b)	Valve Port B
(c)	Valve Port C
(d)	Valve Port D
(e)	Valve Port E
(f)	Valve Port F
(g)	Valve Port G
(h)	Valve Port H

If the engine is started cold, the system will go to low flow mode, which means the electric water pump runs just enough for the sensors to provide reliable information on the state of the system. As the engine warms up, the heat stays around the combustion chamber and is not taken away by coolant flow. Low flow mode is the fastest method for engine warm up. Low flow mode will not enable if the interior HVAC is turned on.

COMPONENT	CONDITION
Electric Water Pump	Low Speed, Low Flow
Main Rotary Coolant Valve	Low Speed, Low Flow
Block Rotary Coolant Control Valve	Low Speed, Low Flow

Mode 2 (Engine Warm Up With Cabin Heating Only):

 

(1)	Surge Tank
(2)	Turbocharger
(3)	Auxiliary Heater Core (If Equipped)
(4)	Heater Core
(5)	Radiator
(6)	Condenser
(7)	Main Rotary Valve
(8)	Engine Outlet Coolant Temperature Sensor
(9)	Engine Cylinder Head Coolant Temperature Sensor
(10)	Integrated Exhaust Manifold
(11)	Cylinder Head
(12)	Engine Block
(13)	Engine Block Heater
(14)	Engine Block Coolant Temperature Sensor
(15)	Block Rotary Valve
(16)	Engine Oil Heat Exchanger
(17)	Transmission Oil Heat Exchanger
(18)	Radiator Outlet Coolant Temperature Sensor
(19)	Electric Water Pump
(20)	Engine Inlet Coolant Temperature Sensor
(a)	Valve Port A
(b)	Valve Port B
(c)	Valve Port C
(d)	Valve Port D
(e)	Valve Port E
(f)	Valve Port F
(g)	Valve Port G
(h)	Valve Port H

When the driver requests passenger compartment heat or windshield defrosting, the electric water pump will control flow to maximize coolant heat transfer from engine to passenger compartment. This heater circuit is fed by a combination of warmed coolant from the cylinder head, integrated exhaust manifold and turbocharger cooler. The engine coolant flow control valve is at an all-closed position at this time. The warmed coolant goes directly to the passenger compartment heater core. Heater core flow returns to the electric water pump.

COMPONENT	CONDITION
Electric Water Pump	Low Speed or Speed-Controlled to Heater Core Demand
Main Rotary Coolant Valve	Low Speed, Low Flow
Block Rotary Control Valve	Low Speed, Low Flow

Mode 3 (Engine Warm Up With Cabin Heating And Radiator Bypass):

Flow Diagram - Mode 3

(1)	Surge Tank
(2)	Turbocharger
(3)	Auxiliary Heater Core (If Equipped)
(4)	Heater Core
(5)	Radiator
(6)	Condenser
(7)	Main Rotary Valve
(8)	Engine Outlet Coolant Temperature Sensor
(9)	Engine Cylinder Head Coolant Temperature Sensor
(10)	Integrated Exhaust Manifold
(11)	Cylinder Head
(12)	Engine Block
(13)	Engine Block Heater
(14)	Engine Block Coolant Temperature Sensor
(15)	Block Rotary Valve
(16)	Engine Oil Heat Exchanger
(17)	Transmission Oil Heat Exchanger
(18)	Radiator Outlet Coolant Temperature Sensor
(19)	Electric Water Pump
(20)	Engine Inlet Coolant Temperature Sensor
(a)	Valve Port A
(b)	Valve Port B
(c)	Valve Port C
(d)	Valve Port D
(e)	Valve Port E
(f)	Valve Port F
(g)	Valve Port G
(h)	Valve Port H

The cylinder head, integrated exhaust manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. As combustion chamber temperatures get hotter, it is necessary to flow coolant through the cylinder head without losing heat to the radiator or engine/transmission oil heat exchangers. The block rotary coolant valve will allow flow through the cylinder head by opening the radiator bypass loop, which returns coolant directly to the electric water pump.

COMPONENT	CONDITION
Electric Water Pump	Speed-Controlled to Engine Demand
Main Rotary Coolant Valve	Bypass Radiator
Block Rotary Control Valve	Position-Controlled

Mode 4 (Engine Warm Up With Cabin Heating, Radiator Bypass And Oil Heating):

Flow Diagram - Mode 4

 

(1)	Surge Tank
(2)	Turbocharger
(3)	Auxiliary Heater Core (If Equipped)
(4)	Heater Core
(5)	Radiator
(6)	Condenser
(7)	Main Rotary Valve
(8)	Engine Outlet Coolant Temperature Sensor
(9)	Engine Cylinder Head Coolant Temperature Sensor
(10)	Integrated Exhaust Manifold
(11)	Cylinder Head
(12)	Engine Block
(13)	Engine Block Heater
(14)	Engine Block Coolant Temperature Sensor
(15)	Block Rotary Valve
(16)	Engine Oil Heat Exchanger
(17)	Transmission Oil Heat Exchanger
(18)	Radiator Outlet Coolant Temperature Sensor
(19)	Electric Water Pump
(20)	Engine Inlet Coolant Temperature Sensor
(a)	Valve Port A
(b)	Valve Port B
(c)	Valve Port C
(d)	Valve Port D
(e)	Valve Port E
(f)	Valve Port F
(g)	Valve Port G
(h)	Valve Port H

The cylinder head, integrated exhaust manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. Once the optimal combustion chamber temperature has been reached, warmed coolant can be used to quickly raise the engine and transmission to their optimal temperatures. The engine coolant flow control valve will still allow flow through the cylinder head with the open radiator bypass loop but will now also allow coolant flow to the engine/transmission oil heat exchangers. Coolant flows from the bypass and heat exchangers returns to the electric water pump.

COMPONENT	CONDITION
Electric Water Pump	Speed-Controlled to Engine Demand
Main Rotary Coolant Valve	Bypass Radiator and Oil Heating
Block Rotary Control Valve	Position-Controlled

Mode 5 (Engine-Demand Cooling With Cabin Heating And Oil Heating):

Flow Diagram - Mode 5

 

The cylinder head, integrated exhaust manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. At this point, the combustion chamber temperature has reached its optimal temperature and the engine needs to dissipate heat through the radiator. Based on engine temperature, the engine coolant flow control valve will split the flow between the radiator and bypass in a ratio necessary to maintain optimal engine temperatures. Additionally, coolant flow will continue to flow to the engine/transmission oil heat exchangers. Engine oil and transmission oil can take significantly longer time to reach optimal temperatures after the engine is already warmed. Coolant flow from the radiator, bypass, and heat exchangers returns to the electric water pump.

COMPONENT	CONDITION
Electric Water Pump	Speed-Controlled to Engine Demand
Main Rotary Coolant Valve	Position-Controlled with Oil Heating
Block Control Valve	Position-Controlled

Mode 6 (Engine-Demand Cooling With Cabin Heating And Oil Cooling):

Flow Diagram - Mode 6

 

(1)	Surge Tank
(2)	Turbocharger
(3)	Auxiliary Heater Core (If Equipped)
(4)	Heater Core
(5)	Radiator
(6)	Condenser
(7)	Main Rotary Valve
(8)	Engine Outlet Coolant Temperature Sensor
(9)	Engine Cylinder Head Coolant Temperature Sensor
(10)	Integrated Exhaust Manifold
(11)	Cylinder Head
(12)	Engine Block
(13)	Engine Block Heater
(14)	Engine Block Coolant Temperature Sensor
(15)	Block Rotary Valve
(16)	Engine Oil Heat Exchanger
(17)	Transmission Oil Heat Exchanger
(18)	Radiator Outlet Coolant Temperature Sensor
(19)	Electric Water Pump
(20)	Engine Inlet Coolant Temperature Sensor
(a)	Valve Port A
(b)	Valve Port B
(c)	Valve Port C
(d)	Valve Port D
(e)	Valve Port E
(f)	Valve Port F
(g)	Valve Port G
(h)	Valve Port H

The cylinder head, integrated exhaust manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. In extreme hot driving conditions, the engine and transmission become extremely hot and their oils need to be cooled. The engine coolant flow control valve will continue to split the flow between the radiator and bypass in a ratio necessary to maintain optimal engine temperatures and will now allow colder coolant directly from the electric water pump to flow to the engine/transmission oil heat exchangers. Coolant flow from the radiator, bypass, and heat exchangers returns to the electric water pump.

COMPONENT	CONDITION
Electric Water Pump	Speed-Controlled to Engine Demand
Main Rotary Coolant Valve	Position-Controlled with Oil Cooling
Block Control Valve	Position-Controlled

Mode 7 (After Run Cooling):

The after run mode is after key off and is needed only after extreme hot conditions with high engine, oil and coolant temperatures. For after run mode, the same valve positions are used as in Mode 6, but the electric water pump is run at a lower speed to continue cooling.

COMPONENT	CONDITION
Electric Water Pump	Low Speed
Main Rotary Coolant Valve	Max Cooling
Block Control Valve	Open

SHUT DOWN

At engine shutdown, the control valves remain open to permit radiator flow and allow coolant service fill by gravity alone. Both control valves also undergo an diagnostic check after engine shutdown, which is sometimes audible.

Edited January 23 by newdude

[silveradosid]

it is minus 9 farenheit this morning, it is amazing how fast you can get heat in the cab

[Coastie05]

On 1/24/2026 at 10:16 AM, silveradosid said:

it is minus 9 farenheit this morning, it is amazing how fast you can get heat in the cab

I totally agree. I've never owned a vehicle that heats up so quickly. Definitely very happy about that since it's been freezing outside. 

[15 Z71]

Sometimes when it's really cold like low signal digits or negative out my parking brake is on and Sometimes I get service 4wd message and my forward collision light is on. When it sat all night. But only does it Sometimes.  After I drive it and re start it it's all off. Anyone else experienced this before?