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High RPMs on neutral, possible vaccum leak?


New Member
May 29, 2011
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Hey everyone, happens to be my first post!

I just recently bought a used Ranger (2003 2.3L 4cyl) and it just developed a small RPM issue. I'll do my best to be verbose:

When I start the engine, the RPMs are very slow to settle down. Starts out at about 2k and works its way down to ~800 over the course of about a minute. This isn't too abnormal and isn't the real issue.

When I hit the gas, still in neutral (or even in gear, for that matter), the RPMs obviously go up. However, they hang around 1500 for just a second or two, before dropping back to the regular ~800/900.

What I have done so far:

I disassembled the throttle body and cleaned it out. Note that I did not replace any of the gaskets for the TB, I simply took a drop of olive oil and ran it over the existing gasket to "reseal" it. Took a look at the TPS, dosen't look overtly damaged, and the fact that the truck accelerates alright tells me that it is likely not my main issue, if at all. I took off and looked at my IAC valve, and it looked a bit dirty, but I was told over at the local parts store it is highly likely not to be the problem, as the car does not stall. I did not clean the valve.

Also, when I hit the throttle from within the engine compartment, there is a hissing sound apparently coming from the throttle body/manifold cover area. Just off sound alone, it appears that is where it's coming from, however I cannot locate any leak with plain soapy water.

I'm thinking it must be a vacuum leak, but I just cant find it???

Now, mind you, the issue did improve after I removed and cleaned the throttle body. Before, it was revving up to 2k RPM before dropping back down to the normal ~800/900 RPM. Not sure if that was coincidence or if the cleaning actually helped that much.

This truck has been my first foray with auto mechanics. I've generally got a knack for this sort of thing, but when you don't know the nature of what you're working on (i.e. the rules of the game) its a bit harder to play.

Anyways, suggestions are obviously welcome. Would appreciate any past experiences with similar issues.


PS: Figured it was fitting that my user name reflect my first issue with my truck... hopefully that doesn't turn out to be horrible luck

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