I have a 05 Mini Cooper s the past couple months my gas mileage has dropped to around 23mpg, where before it was at least 29mpg. I cannot figure out why, my girl just turned over 130k miles. I just bought new spark plugs it's been about 50k miles since. the air filter is clean and changed every oil change( I have 2 I clean I don't buy new every time). I have also noticed a loss in power, I was reading a out the timing tensioner? Any info on that would be great also.

My question is what can I do to improve my gas mileage. Also what would be some things to look at replacing. Should I change out the fuel filter maybe new plug wires or ignition coil. To my knowledge everything is original on the car except the air intake and reduced supercharger.

Also what else should I look at being high mileage. Nothing major has ever been done I want to make it well past 200k so any preventative maintenance advice would be nice. Thanks and happy motoring

 

Could be a difference in your driving or the quality of gas at specific gas stations. Some have better gas than others. Also, highway driving verses city driving. Maybe run a can of BG 44k into your gas tank. You'll see a drop in MPG with that tank, but once you burn through that tank the BG will help with MPG for a little. You can also take a look at our tech articles and see what other maintenance services you can perform to help keep it running for many more years.

-Luccia

 

Feel you rear brakes....see if one is warmer than the other....
Next...I might suggest some seafoam through the pcv...clean up the map/t-map....washable cotton gauze filters are good for 50,000 miles plus between cleanings unless you live in a very dusty place.... So I'm thinking your sensors are oiled up pretty well...
If it persists, might be worth doing a compression check...might be some valve wear, but just a guess.

 

Most don't realize that the pre-cat O2 sensor is the feed back sensor to the ECU that controls the fuel systems. The O2 sensor voltage that is sent back to the ECU represents if the engine is burning a rich or lean Air/fuel mixture. The ECU make adjustments to the Fuel trims to correct the mixture. An old O2 sensor may not pull a MIL code but could be marginal because of it is slow to respond to the change in the detected O2 levels. If you have a ODB2 meter that can graph the pre-cat O2 sensor voltage it should look some what like a sine wave transitioning between .9 to .1 volt. Before swapping out the O2 sensor you should check the overall tune, plugs, airfilter, gas quality,etc,etc. But don't over look the possibility that the Pre-cat O2 sensor could be a culprit, especially at 130K miles

 

Yea my service engine light came a while ago, I had a buddy read the code and it was an O2 sensor don't know which one though. The light is intermittent it comes and goes so when it comes back I am going to have a professional read it and find out which one. Any idea if Rhodes are a pain to replace or not?

 

The Mini has only a single bank(#1), sensor#1 is the pre-cat and sensor#2 is the post-cat. Sensor#2 (post cat) is easy to remove, but Sensor#1 (pre-cat) is a little more difficult because of the tight fit. You will have to get a 22mm Sensor tool (a socket, maybe 5 bucks) to make is a little easier. The Pre-cat sensor connector is in the engine compartment. It is mounted on a metal bracket, to remove it turn the connector about 90 degrees and pull up.

 

+1 on the sensor , you will see the mileage drop, then eventually get a CEL light and its reads cat one or cat two malfunction.

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But first make sure the rear brakes are not dragging:

https://www.northamericanmotoring.co...rake-wear.html