The controls for that sit right on the front of the engine and when the engine reaches a certian RPM it opens, well mine stopped opening and I lost a lot of top end power, I use to have a powerband around 3500-4000 RPM. So what I did was Tie that lever open to see if that was my problem and now I have that top end power back, but the low end sucks now and it gets about 10 mpg.