Hi all. I have a 2008 Land Rover Range Rover 4.2L Supercharged full size. I am having an issue when letting off of the gas pedal at low speeds (under 25 mph) where the rpm will continue to climb for a few seconds to about 2,000-2,500 rpm. Some things I have tried are cleaning Mass Air Flow Sensor, cleaning throttle body, replacing PCV valve, changing Air Filter. Still have the problem. Could it be an issue with the Supercharger? Any thoughts would be greatly appreciated.

2008 Land Rover Range Rover 4.2L Supercharged

 

No codes? Does it slowly lag down to idle or does it return normally after the initial run-on? A faulty or misaligned Throttle Position Switch will exhibit those characteristics.

 

Thanks for your reply Ahab. I have no codes. The rpm returns to normal after a few seconds after I let off of the gas pedal. The surge in the rpm after I let off of the gas pedal can happen several times on the same drive at speeds under 25 mph stop and go traffic or in parking lots. More noticeable on hot days. It is not a persistent problem but happens several times a week.

 

I will concede that I know very little about supercharged Range Rovers however the function of the TPS is to tell the ECU that the throttle plate is closed, and therefore to cut fuel delivery back to idle maps. If your truck has a TPS, that's where I'd look.

 

Thanks. I will look into it and let you know what I find out.