High idle when parked after driving

[eREdge]

Well I'll post this again since my last one didn't get any answers and the truck is acting up again...

Original post

Another day, another problem lol recently my ranger has been acting up again. This time, it starts to idle high at 1500 to 2000 RPMs in Park after it's been warmed up and driven. When I shift it back to drive or reverse the idle drops down to 1200 or so whatever is normal. When I rev it in Park the RPMs don't drop. It stays consistently at high idle. Only when I restart the truck the RPMs are normal until I drive and park it again.

Under the hood, the lines look fine, I don't hear any hissing. And I cleaned the throttle body, mass airflow sensor and IAC when I bought the truck a few months ago. And no, there were no codes when I scanned it.

Need some insight

 

[Craig0320]

Sounds like a faulty idle air control valve but when is the last time you replace your PCV valve

 

[hank857]

disconnect the IAC and see what happens. Mine has been disconnected for over 150000 miles no issues.

 

[eREdge]

Yeah the PCV valve is new and didn't make a difference.
I'll try disconnecting the IAC when I can. They're not that expensive so I'll replace it if it's faulty

Thanks for the suggestions, guys!

 

[telsar]

Look at live data with a scan tool. Should show something out of wack.

 

[91stranger]

my old 2.3 did that same thing. I never worried about it because it idled fine while driving. Mine had the 8 spark plugs so I just figured it was common with those lol

 

[eREdge]

Look at live data with a scan tool. Should show something out of wack.

How do I read live data and determine what's out of wack?

 

[eREdge]

my old 2.3 did that same thing. I never worried about it because it idled fine while driving. Mine had the 8 spark plugs so I just figured it was common with those lol

Does it sound like engine is being revved high? That's how mine sounds

 

[eREdge]

Bump. Happened again last night. I popped the hood and went to disconnect the IAC valve but as soon as I touched it the problem went away

 

[Denisefwd93]

Bump. Happened again last night. I popped the hood and went to disconnect the IAC valve but as soon as I touched it the problem went away

Loose connector would be my guess

 

[rusty ol ranger]

I had an aerostar (yeah dont laugh) once that did this and it was in the cruise control shit. I cut some wires and fixed it.

 

[eREdge]

Loose connector would be my guess

I doubt it. I have disconnected it and cleaned it twice because of this. I always push it til it clicks

 

[1990RangerinSK]

I doubt it. I have disconnected it and cleaned it twice because of this. I always push it til it clicks

Just because it clicks doesn't mean it's a tight connection.

 

[Dirtman]

disconnect the IAC and see what happens. Mine has been disconnected for over 150000 miles no issues.

If your IAC is disconnected and your truck can still idle decently you've had a vacuum leak for 150,000 miles...

 

[Denisefwd93]

Let me add this to the mix, check your brake booster, or check your vacuum by plugging the vacuum line from the brake booster.

I had a bad booster on my truck it made a groaning noise and had a constant but not large vacuum leak.

truck definitely has a better idle now when and doesn't race when starting cold