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Lotus Elise / Lotus Exige. Instruction - part 43

Page 46

Lotus Service Notes

Section EMP

EMP.4 - MECHANICAL THROTTLE SETTING PROCEDURE (Prior '06 M.Y.)

To avoid throttle cable strain, and ensure correct idle control and pedal operation, the following adjustments

must be maintained. If the pedal downstop is incorrectly set, overloading of the throttle body cable quadrant

can occur, resulting in quadrant distortion, closed throttle position error and engine stalling:

1. Check the throttle body cable quadrant for distortion and mis-alignment. If necessary, repair or replace

the quadrant.

2. Check that there is 2 - 3 mm free play at the throttle pedal, adjusting at the throttle body cable abutment

bracket if necessary.

3. If an idle control problem has been reported, reset the closed throttle stop screw on the throttle body:

With ignition off, use a hexagonal key in the bottom end of the throttle stop screw to allow the throttle but-

terﬂy valve to fully close, and introduce clearance between the screw and quadrant stop bracket. Screw

upwards until contact is just made, and then a further ½ turn upwards. Secure with the locknut. Recheck

cable adjustment as above.

4. Adjust the throttle pedal downstop such that vigorous full depression of the pedal achieves full opening of

the throttle butterﬂy without allowing the cable or mechanism to be strained.

5. If the throttle stop screw was adjusted, allow the engine to idle for 15 minutes to relearn settings.

6. An alternative pedal position which may be preferred for 'heel and toeing', may be achieved by replacing

the rubber upstop buffer with an M5x15 hex. head setscrew, with three ﬂat washers beneath the head for

a total thickness of around 7mm. The cable must then be re-adjusted at the engine abutment as above.

The foopad downstop bolt should then be replaced by an M8x20 setscrew and reset as above.

Throttle cable

Closed throttle

stop bracket

Cable quadrant

Throttle stop screw

sb77

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Lotus Service Notes

Section EMP

Page 47

EMP.5 - 2006 MODEL YEAR ELECTRONIC THROTTLE CONTROL (ETC)

For '06 model year, the 2ZZ-GE engine is equipped with an electronic 'drive by wire' throttle in order to

meet Low Emissions Vehicle 2 emissions standards as dictated by California Air Resources Board. This is

achieved by allowing fuel pre-scheduling and consistency of load demand.

The mechanical throttle control cable is replaced by a pedal actuated potentiometer unit which feeds

pedal movement and position information to the engine management ECU. The ECU compares this demand

information with existing engine throttle position data, and outputs a suitable command signal to the DC step-

per motor which operates the throttle valve. For optimum safety, two output curves are produced by the pedal

unit and are fed into two processors contained within the ECU. Similarly, two streams of engine throttle valve

positional information are fed back into these processors, which are then compared by the ECU software. Any

discrepancies are analysed and appropriate safety oriented commands outputed to the throttle valve which may

be limited to a maximum 15% opening, or to a 7% mechanically sprung setting for 'limp home', or in extreme

cases, the injectors may be shut off.

Note that no IAC valve is required, as the idle air control function is incorporated into the electronic throt-

tle system.

ECU Communication

2006 model year cars with ETC have the VIN included in the ECU memory, without which the MIL will be

illuminated, and a fault code stored. The Lotus Scan tool requires an updated operating programme which

includes VIN download facility and is available on CD under part number T000T1466/2. This programme must

be downloaded on to a PC before being transferred to the Scan tool. The ECU progamme is also speciﬁc to

ETC, with an i.d. of A120E0030H (non USA) or A121E0010H (USA) .

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Lotus Service Notes

Section EMP

EMP.6 - DIAGNOSTIC CODE SUPPLEMENT - '06 M.Y.

New fault codes for '06 M.Y. cars with electronic throttle control are as follows:

DTC Fault Description Page

P0016 Crankshaft Position – Camshaft Position Correlation Error 49

(P0121/P0122/P0123 Throttle Position Sensor 'A' - see page 12)

P0222 Throttle Position Sensor 'B' Circuit Low 49

P0223 Throttle Position Sensor 'B' Circuit High 49

P0630 VIN Not Programmed or Incompatible – ECU 50

P0638 Throttle Actuator Control Range/Performance 50

P2100 Throttle Actuator Control Motor Circuit/Open 51

P2102 Throttle Actuator Control Motor Circuit/Low 51

P2103 Throttle Actuator Control Motor Circuit/High 51

P2104 Throttle Actuator Control System – Forced Idle 51

P2105 Throttle Actuator Control System – Forced Engine Shutdown 52

P2106 Throttle Actuator Control System – Forced Limited Power 52

P2107 Throttle Actuator Control Module Processor 52

P2108 Throttle Actuator Control Module Performance 53

P2122 Pedal Position Sensor 'D' Circuit Low 53

P2123 Pedal Position Sensor 'D' Circuit High 53

P2127 Pedal Position Sensor 'E' Circuit Low 54

P2128 Pedal Position Sensor 'E' Circuit High 54

P2135 Throttle Position Sensor 'A'/'B' Voltage Correlation 54

P2138 Pedal Position Sensor 'D'/'E' Voltage Correlation 55

P2173 Throttle Actuator Control System – High Airﬂow Detected 55

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Lotus Service Notes

Section EMP

Page 49

Crankshaft Position–Camshaft Position Correlation Error P0016

Description

The crankshaft position sensor is used to identify engine position and speed via a pole wheel mounted on the

front end of the crankshaft. The camshaft position sensor is used to determine camshaft position from a three

vane reluctor on the rear end of the inlet camshaft. The Variable Valve Timing system (VVT) on the inlet cam-

shaft can vary the timing by up to 25°, with fault codes P0011 and P0012 allocated to errors with the variable

timing. Fault code P0016 indicates a mechanical timing error such as incorrectly set, or 'jumped' cam timing.

Enable Criteria:

# Engine running (for up to 4 seconds)

Disable Criteria: None

Potential failure modes:

# Crankshaft/Camshaft alignment

Throttle Position Sensor 'B' Circuit Low P0222

Description

Two potentiometers are built into the throttle valve actuator unit in order to provide a throttle position signal to

the ECU. Note that the sensors operate on 5 volts.

Enable Criteria: None

Disable Criteria: None

Potential failure modes:

# Signal short circuit (< 0.283 V)

# Reference voltage open circuit

# Reference voltage short to ground

# Sensor failure

Notes: A maximum throttle opening of 15% may be imposed due to this single code. In the case of multiple

codes, a mechanically sprung 7% opening may be applied.

Throttle Position Sensor 'B' Circuit High P0223

Enable Criteria: None

Disable Criteria: None

Potential failure modes:

# Signal open circuit (> 4.487 V)

# Reference voltage open circuit

# Reference voltage short to ground

# Sensor failure

Notes: A maximum throttle opening of 15% may be imposed due to this single code. In the case of multiple

codes, a mechanically sprung 7% opening may be applied.

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