2002 Ford F-150 Will not idle in Park

WOODROW95

MEMBER
2002 FORD F-150
V8
2WD
AUTOMATIC
98,000 MILES

I have a 2002 F-150 Supercrew w/ a 4.6L V8 (about 98K miles). When I start the engine, it will not hold an idle and stalls. If I start the engine and hold the RPM at about 1500 for a few seconds, I hear a 'pop' noise followed by a 'hiss', then it idles just fine. If I start the engine and immediately put it into gear, it will idle OK, but not that well. Other than when it is started, the truck runs just fine.

Here's what I've tried:
-Cleaned the PCV valve & checked hoses (best I could for a quick once-over)
-Cleaned and lubed the IAC valve (with good resistance checks)
-Cleaned the MAF sensor

Someone recommended cleaning the EGR valve, but I did that same thing about 6 months ago. Plus changed the DPFE sensor.

Haynes recommended removing the PCV valve while idling and checking for a vacuum. When I did it the engine died.

Thank you for your time. Have a great day!

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,355 POSTS

When you pulled the PCV, you created a large vacuum leak causing the engine to die. However, it sounds like a vacuum issue. The hissing and pop you hear, can you tell aprox where it is coming from? To me, any hissing is a vacuum leak.

Let me know.
Joe

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Friday, July 2nd, 2010 AT 10:00 PM

WOODROW95

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4 POSTS

Its been a week since I did the last repairs/cleaning and the truck seems to start and idle fine now. Both my wife and I have driven it the past few days without any start-up problems.

Joe, I thought it was a vacuum issue too, but I discovered the 'pop and hiss' only happens when the A/C is on, but not when the vent is on. Maybe its the A/C compressor kicking on or something (?).

I am still not convinced yet, but we'll see how she does in the upcoming week. I appreciate any feedback. Thanks!

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Monday, July 5th, 2010 AT 9:36 PM

JACOBANDNICKOLAS

MECHANIC
108,355 POSTS

It could be the compressor clutch. It will click (pop) on and when engaged, is can make a noise that may sound like a hissing.

Let me know how things go or if you have other questions.

Joe

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Monday, July 5th, 2010 AT 9:54 PM

WOODROW95

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4 POSTS

Could the compressor clutch cause the stalling problem I was seeing?

I'll keep you posted. Thanks again for all the help.

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Tuesday, July 6th, 2010 AT 12:01 PM

WOODROW95

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4 POSTS

OK, here's the latest.
-Replaced the EGR valve (& gasket)
-Replaced the IAT sensor
-Replaced a badly worn hose from the distributor(?) To the throttle body intake

Not sure which one did it, but the truck seems to start just fine now. I'm not sure I'm convinced, as my troubles began when the summer rolled around and I think it has something to do with the heat. But we'll see. Thanks for all the help!