Lower Limit

Checking Throttle Body
- Ignition off.
- Check that seal on throttle body (TB) adjusting screw is not broken.
- Is seal broken?

No:
^ Proceed to test step below.

Yes:
^ Replace throttle body.
^ Then proceed to Verification section below.





Checking Link
- Ignition off.
- Check that the throttle spindle is in contact with the adjustment screw and that the throttle pulley is in contact with the idling stop.
- Is the throttle mechanism OK?

Yes:
^ Proceed to test step below.

No:
^ Check and adjust throttle spindle and throttle cable.
^ Then proceed to Verification section below.





Checking For Air Leakage
- Ignition off.
- Check for air leakage.
- Is there any leakage?

Yes:
^ Remedy as necessary.
^ Then proceed to Verification section below.

No:
^ Proceed to test step below.





Checking Idle Air Control Valve
- Ignition on.
- Activate idle air control (IAC) valve.
- A "clicking sound" should be heard from the valve.

If reading is OK:
^ Proceed to Checking Idle Air Control Valve Resistance section below.

If reading is incorrect:
^ Proceed to test step below.





Checking The Idle Air Control Valve Connector
- Ignition off.
- Check the idle air control valve and engine control module (ECM) connectors for contact resistance and oxidation and remedy.
- Reinstall engine control module and idle air control valve connectors.
- Ignition on.
- Activate idle air control valve.
- A "clicking sound" should be heard from the valve.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try a new idle air control valve.
^ Then proceed to Verification section below.





Checking Idle Air Control Valve Resistance
- Ignition off.
- Disconnect idle air control valve.
- Connect an ohmmeter between idle air control valve terminals 1 and 3.
- The ohmmeter should read 18 - 28 ohms at +20°C.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try a new idle air control valve.
^ Then proceed to Verification section below.





Checking Throttle
- Ignition off.
- Remove fresh air intake between air cleaner (ACL) and throttle body.
- Check that the throttle is undamaged, that it moves properly and that it has not come away from the throttle spindle.
- Is the throttle OK?

Yes:
^ Try a new idle air control valve.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Replace throttle body.





Verification
- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition on.
- Throttle position (TP) sensor and engine control module connected.
- Ignition on.
- Erase all adaptive functions but the flywheel.
- Start the engine and run it until it reaches operating temperature, at least 850°C.
- Engine idling.
- Read off idle air trim adaption.
- When the idle air trim adaption value has stabilized. Rev the engine to approx. 2,000 and idle it.
- Wait approx. 30 seconds and read off the value again. Repeat this until the value is stable.
- The value should be between -5 and +15 kg/h.

If reading is OK:
^ Fault corrected

If reading is incorrect:
^ Proceed to test step below.

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected

No:
^ Return to Checking Throttle Body section above.