High rpms at start up

[Bo Loo]

Hi,



Lately, when I start the ST, it revs higher than usual/normal - too high; around 2200 until I put in gear.



Sometimes, it will slowly adjust down to the 1800 range before I shift into gear, but is still a bit too high for idle.



Also, recently on 2 occasions, while stopped at a red light, the engine "shuddered", but otherwise ran fine.



Once I do put it in gear, it generally runs OK.



Ideas?

 

[Vic Sorlie]

How many miles? I'd look at intake system, starting with air filter. Clean MAF sensor, throttle body and IAC (see Projects section this site). Replace EGR valve. Add bottle of injector cleaner to fuel tank.

 

[EddieS'04]

Have you cleaned the IAC and TB lately.?

 

[swshawaii]

+3 Vic and Eddie. Service all three, but start with the IAC. Easiest to clean and well known fix for idling issues.



Also check the PCV elbow linked below if you haven't yet.

http://www.explorerforum.com/forums/showthread.php?t=314670

 

[Scott Tanner]

100% your IAC valve....

 

[Kody Budinger]

I have this same problem. Sometimes when working on my engine things get messed with such as this hose that connects to the intake from the engine (not sure the exact name for it) but that hose regulates your idle and once in a while it comes disconnected and I will know when my rpms shoot up when I turn on the truck. Check that hose.

 

[Bo Loo]

Many thanks for everyone's input. I know what my weekend plans are.



Updates to follow.

 

[Taylor Corn]

Sea Foam in the tank and the brake booster vacuum line. Works wonders for me and I just used in in my intake because of hard starting, starts like new now and settles fast.

 

[Bo Loo]

Cleaned the MAF, IAC and throttle body and it's running normal again. Of note, I didn't need the torx T20 to remove the MAF, i just removed the air intake housing and sprayed the MAF sensor.



It had been idling around 2400 at startup and then would fall to 1800; now the start up idle is 1700 and falls to 1200.



Idle falls below 1000 once put into gear.



Thanks again for everyones assistance.

 

[Yardsale]

1000 RPM seems high. Mine hovers around 700 warm. Is that when the engine is warm?