Dash warning - Diminished Engine Performance

[olbear1962]

have a 2007 RR Supercharged, 28k on the clock and had it 2 weeks. I am currently on a long road trip - all highway and interstate. I gassed up at a Love's Super Gas Station- Premium gas of course and not 5 miles down the road I had the engine warning light come on and a code on the dash came up "diminished engine performance" or similar wording. It was like the supercharger was "turned off" and throttle was limited (like a "limp home mode"). Pulled over, shut engine off waited a few minutes started up and all was good. About 25 to 30 miles down the road this happened again... did the same thing. After this happening 4 times I was finally thru the tank of gas and refilled at a Shell gas station. About 150 miles later no "engine performance" issues happened and the engine light went off. Went thru the whole tank of gas no issues - was it just bad fuel??

Has anyone else had this issue?? Am new to Range Rover Supercharged autos, and was panicked for a while.......

 

[joey]

Sadly bad fuel sound like the issue... I normally have no issues with Love's fuel, but it can happen at any station, if they just filled the tanks it could have got enough of the water and sediment into the fuel to cause you an issue.

 

[umbertob]

It sounds a little too coincidental to be anything but bad fuel in your case, but I have had "Reduced Engine Performance" fault messages pop up on my 2006 RRS (HSE) because of a dirty MAF sensor in the past - the result of off roading it, I pulled it out, cleaned it and solved the problem. Also, on S/C engine the cooling pump of the supercharger could malfunction at high engine loads (there were actually a few auxiliary pumps that were miswired at the factory between 2006 and 2007, TSB # LTB00041), causing a similar power loss as the ECU cuts power to prevent overheating of the blower, and throws that same fault message on the dash. If I were you I would bring up the issue with your SA next time you are in for service, hopefully a DTC has been stored identifying the issue that caused that fault message.

 

[olbear1962]

It sounds a little too coincidental to be anything but bad fuel in your case, but I have had "Reduced Engine Performance" fault messages pop up on my 2006 RRS (HSE) because of a dirty MAF sensor in the past - the result of off roading it, I pulled it out, cleaned it and solved the problem. Also, on S/C engine the cooling pump of the supercharger could malfunction at high engine loads (there were actually a few auxiliary pumps that were miswired at the factory between 2006 and 2007, TSB # LTB00041), causing a similar power loss as the ECU cuts power to prevent overheating of the blower, and throws that same fault message on the dash. If I were you I would bring up the issue with your SA next time you are in for service, hopefully a DTC has been stored identifying the issue that caused that fault message.

Umbertob, Thanks very much for your reply. I will be taking in the RR SC on Saturday morning to my local dealer when I get back to Dallas. In todays driving, Today I had more hills (higher loads) than when the code/message came up and no issues - finger crossed......
My SA responded to me today and has ordered the required parts and mentioned the exact same issue you did. Am glad I was able to get a second opinion from the forum. thanks again...