I changed the solonoid and check valve. When I go up a hill at high speed SOMETIMES the tin can noise is heard. The IWE trying to engage. I just bought a hand vacuum pump to dig deeper. I read that a member put inline another check valve? Any suggestions on a fix. The IWE system works fine, expect on a hill during a 2 hour trip. I may hear the noise once or twices. Taking my foot off the gas , the vacuum builds and all is good. Suggestions.