VVC Information

The S1 143bhp EU2 VVC is controlled by the Lucas MEMS 2J ECU common with the early VVC MGFs

The S2 156bhp EU3 VVC is controlled by the Lotus K4 ECU (based on the Lucas MEMS 3 but NOT the same as the MGTF160).

EU3 & EU3 Differences

The mechanicals which are different from the EU3 to EU2 engine:

1. 52mm TB as standard (EU2 48mm)

2. Wasted spark coil packs on top of the plugs (EU2 under induction)

3. KTM plate oil/water cooler under the induction (EU2 none)

4. Dark blue 192cc/min injectors (EU2 cream 218cc/min)

5. TF160 pistons with marginally higher compression and expanded ring belt to strengthen ring lands, indentifiable by '160' engraved on the crown

6. Machining of the head around the inlet and exhaust valves both in the valve throats and combustion chamber to improve low lift flow

7. VVC control connectors are differnt colours and have different keyways

8. IACV MDQ100170 is PWM (EU2 is Stepper)

9. Cam Position Sensor NSC000010 has a longer pickup

VVC Failure Modes

ECT Sensor Error Limits to 6K RPM

MAP Sensor Error limits to 6K RPM

VVC Solenoid low resistance (should be 6.6 to 8.8 Ohms) Limits to 5.5K RPM

Cam Position Sensor Limits to 5.5K RPM (The VVC CPS is NSC000010 variable reluctance, different to the standard K16 Hall effect)

Excellent write up on the S1 EU2 VVC MEMS 2J logic and failure modes here * http://www.mgfcar.de/library/ENGINE_MANAGEMENT_SYSTEM_VVC_MEMS_2J.htm

Excellent write up on the S2 EU3 VVC MEMS 3 logic (which the K4 is based on) and failure modes here * http://www.mgfcar.de/library/ENGINE_MANAGEMENT_SYSTEM_%20MPi_VVC_MEMS_3.htm

Note: Connecting the battery on wrong polarity can blow the K4 ECU VVC control circut, as can running with a low resistance solenoid. Lotus issued a service note on this.

Lotus S2 K4 ECU VVC Connections

K4 Pin	Wire	Function	Connector
06	Blue	VVC Oil Temp Earth	BLACK
10	Green Orange	VVC Oil Temp Signal	BLACK
12	Black Yellow	VVC Decriment	BLUE
49	Brown Black	VVC Increment	BROWN

The S2 Connector order is LEFT < Blue - Brown - Black > RIGHT VVC Actuator

The S1 connector order is LEFT < Blue - Black - Brown > RIGHT VVC Actuator

Lotus S2 K4 ECU VVC DTC Codes

The S2 ECU is ODB2 compliant (ISO9141/KWP2000) so can be read by most scantools. Of course the S1 MEMS isn't OBD2 so no idea what that spits out ...

Code	Description
P1336	S2 Crankshaft Position System Variation Not Learned
P1480	S2 Exhaust flap relay open
P1481	S2 Exhaust flap short circuit
P1490	S2 VVC brown increment solenoid open circuit (Black Yellow)
P1491	S2 VVC brown increment solenoid short circuit (Black Yellow)
P1492	S2 VVC blue decrement solenoid open circuit (Black Brown)
P1493	S2 VVC blue decrement solenoid Short circuit (Black Brown)
P1494	S2 VVC black oil temp sensor LOW open circuit (Green Orange + Blue)
P1495	S2 VVC black oil temp sensor HIGH short circuit (Green Orange + Blue)

VVC and Emerald ECU

Emerald K3 ECU needs to be firmware revision 1.13 to filter out Cam Position Sensor noise that can cause VVC cam control issues at high RPM.

External Resources

VVC Sensors * http://homepage.swissonline.ch/TomsSeven/Navigation2/Map.htm

VVC Sensors * http://www.mgfcar.de/sensor/index.htm

VVC Mechanism Assembly * http://www.davebence.co.uk/mods_10.htm

VVC Timing * http://forums.mg-rover.org/showthread.php?p=1940938