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Q: RPM going up and down with hard startup on a Fusion

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I have my Fusion parked. I've noticed my RPM go up and down noticeably. I don't recall this before. I remember the times when the AC was up and definitely when it was on. I think the car starts hard too, like 1500. Do you think it is hill related?

A: If it only happens when you are on a hill, ...

If it only happens when you are on a hill, it is definitely hill-related. The fuel pump could be starting to go out, because then all the gasoline slides to just one side. But more often, if it happens all the time, it is either the carbon building up, the throttle that needs cleaning or a vacuum leak that is present. So, try my video "how to fix the car that idles poorly" and try cleaning the throttle. You can also watch my other video, "finding engine vacuum leaks with a cigar" and try to find where the vacuum leak is. A lot of times when you get a vacuum leak, it is going to go up and down and it’s going to idle higher because it is sucking more air in. If you still need help with this, you can have a certified technician from YourMechanic inspect your engine’s high idle and let you know what repairs are needed.

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