I have a pretty stock engine that used to get 400km out of a full tank. Gradually over the last 6 months it is getting worse and worse. Last night I filled up at 300km. I drive mostly always in the city. My engine runs just as good if not better than the day I used to get 400km out of a tank. One thing that did happen 4 days ago was a symptom I had with my old engine flooding and having to use my aftermarket switch to cut off the fuel and flipping it on once it started. That never happened with this engine. The conditions aren't dramatically extremely cold this year either and don't warm up my car. What is going wrong?

Thanks

 

you might want to invest in a new O2 sensor. that helped me get much better gas mileage in my n/a. also, throw some fuel injector cleaner in there...or maybe sending away the injectors to get cleaned would help wtih the flooding issue.