High Idle After Cleaning Throttle Body? Land Rover ETC Reset Guide

Your Land Rover LR4 or Range Rover was idling a bit roughly.

You watched a YouTube video, bought a can of cleaner, and scrubbed the carbon buildup off the Throttle Body. It looks brand new now.

But when you started the engine, disaster struck. The RPMs shot up to 2,000. Or worse, the engine is "hunting"—revving up and down uncontrollably. The Check Engine Light is on.

Don't panic. You didn't break it. You just confused the computer. Here is how to fix the "High Idle" problem using the iCarsoft LR V4.0.

iCarsoft LR V4.0 ETC Reset Tool

The "Re-Learn" Button for Your Engine

Why Cleaning Caused High Idle

Over time, carbon builds up around the throttle plate (butterfly valve), reducing airflow.

The Engine Control Unit (ECU) is smart. It slowly opens the valve wider and wider over the years to compensate for this blockage.

The Conflict: When you clean the carbon away, the gap suddenly becomes huge. But the ECU still thinks the valve is clogged, so it keeps it wide open.

Result? Too much air rushes in, and the engine races.

The Fix: ETC Adaptation Reset

You cannot fix this by driving around. You must wipe the old "adaptation values" and force the ECU to learn the new "Zero Position."

Step 1: Connect and Prepare

Plug in your iCarsoft LR V4.0.
Turn Ignition ON, but keep the Engine OFF. (This is crucial!).
Ensure the battery voltage is good.

Step 2: Perform the Reset

Select Service > ETC (Electronic Throttle Control) > Land Rover.
Select your model (e.g., Discovery 4 / LR4).
Choose "Reset Adaptation Values" or "Throttle Valve Adaptation".
Press OK. You might hear a click-whirr sound from the engine bay. That is the throttle valve opening and closing to measure its range.

Step 3: Verification

Once the screen says "Successful," turn the ignition OFF for 10 seconds. Then start the engine.

The idle should immediately drop to a smooth, steady 700-800 RPM. No more surging.

Still Running Rough?

If you reset the throttle body but the engine still shakes or knocks, the issue might not be airflow—it could be fuel.

On diesel models, this is often a sign of uncalibrated injectors. Check our guide on How to Code Fuel Injectors to solve persistent rough idle issues.

Finish Your DIY Job

Cleaning parts is only half the battle on modern cars. The other half is telling the computer you did it. Get the iCarsoft LR V4.0 to complete the repair.

Get Your Adaptation Tool