01 Exp - High Idle+ Stuck Throttle + Vacuum Leak
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01 Exp - High Idle+ Stuck Throttle + Vacuum Leak
Hello, I have an 01 Expedition with 180k miles on it, it isn't exactly in the best shape but I keep up with fluid/brake changes. Recently I have been encountering a problem where when you start the truck it starts at around 3k RPM then over the next 10-15 seconds it drops down to a high idle of around 1.5k If I give it some gas it takes the same amount of time to come down.
The dangerous part is when I am driving the high RPM increase my speed and really took my off guard when trying to brake against the motor raging at 2k RPM.
What i've done:
Cleaned the IAC + replaced gasket.
Manually operated the butterfly throttle and didn't notice any sticking.
Replaced the TPS.
Cleaned the MAF.
After I did all these I noticed a noticeable air leak coming from somewhere.
I searched for vacuum diagrams on the forums but it doesn't give me any perspective to the location of them.
The hoses in question are on the passenger side of the engine, right above the (I think fuel rail). Is there anything in that area that could cause a hissing sound and likely attribute to my problem?
I will get better picks in a bit.
The dangerous part is when I am driving the high RPM increase my speed and really took my off guard when trying to brake against the motor raging at 2k RPM.
What i've done:
Cleaned the IAC + replaced gasket.
Manually operated the butterfly throttle and didn't notice any sticking.
Replaced the TPS.
Cleaned the MAF.
After I did all these I noticed a noticeable air leak coming from somewhere.
I searched for vacuum diagrams on the forums but it doesn't give me any perspective to the location of them.
The hoses in question are on the passenger side of the engine, right above the (I think fuel rail). Is there anything in that area that could cause a hissing sound and likely attribute to my problem?
I will get better picks in a bit.
Laughing Gas
Joined: Feb 2003
Posts: 877
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From: South Florida
The PCV valve and associated plumbing is right there on that valve cover. Could be a HUGE source of your vacuum leak. Also when was the last time the fuel filter was changed ? On my Bronco the blocked fuel filter caused the high idle symptoms you described. But if you're hearing a big vacuum leak fix that first. Get a can of carb cleaner and spray it around the motor where you suspect a vacuum leak to see if you get an associated rpm response.
-Mike
-Mike
Fleet Owner
Joined: Apr 2008
Posts: 24,319
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From: 0,0,1
Disconnect the cable that runs from the cruise control servo to the butterflies and see if the problem goes away. If the servo is sticking or otherwise acting up, it could pull on the throttle.
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Okay, tried a few things, I found what I believe is the PCV valve.. it doesn't look like its in good shape, but QUESTION: where does the hose end so I can replace them both? Hopefully this is the problem I am looking for. I am a broke college student so I can't exactly run around fixing trivial/non essential items on a 12 year old car.
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Okay, this definately looks like it has been replaced before, funny since the truck has been in the family since 2007 (at 70k miles). This has ghetto rigged all over it.. ( stupid good year mechanics). I didn't replace the long tube which may be cracked, I should have but its routed REALLY deep in there. I replaced the cheap right angle that was taped to the other side with a proper right angle, I found a 100% fit in the MISC tube parts of auto zone. i think the rest of the tube might have a leak or I have another leak somewhere. The truck no longer idles as badly, instead of 1500 it drops down to 1000 then 700, I would say problem is fixed but until I let the comp sort the idle out I wont know for sure, but its definitely better. Thanks guys.
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HEpTJJ
1987 - 1996 F150 & Larger F-Series Trucks
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Sep 11, 2013 10:58 PM
