stalling '99 5.4
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New User
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stalling '99 5.4
Hey guys, have heard many good things about the site and was sent here from the diesel stop. question, a freind of mine has a 99 150 with a 5.4 . A few weeks ago it started stalling at stop lights and eventually got worse. Now sometimes it will go around the block, but other times it will only go a matter of feet before stopping. She says she recently had a vaccum something-or-other changed for a similiar problem, and has had the fuel filter changed. it hasnt been driveable for a few weeks and i think in a few days we are gonna try and nurse it to a shop but trying to save her some time and money. any ideas of something that might be fairly easy to fix? maybe bad gas? water in something? electrical gremlins?
Thanks so much
Don
Thanks so much
Don
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Elder User
Joined: Jan 2003
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From: Baltimore
The first thing you should do is put a scanner on it and see if it is reporting any codes. If you don't have a scanner ( or a friend with one), take it to Autozone. I think they will scan it for free.
I am wondering if maybe the IAC is gummed up with carbon.
I am wondering if maybe the IAC is gummed up with carbon.
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Thanks for the replys! #1 i read the guidelines and nothing i cant handle. #2 getting codes scanned were also my first thoughts. BUT autozone is like 2 miles away of busy 6 lane roads. due to its issue it could be very risky to try and get there. Also to my knowledge it did not present a CEL or any other flashing lights. could it still have thrown a code? also, over the last 2 years i have kinda lost touch with new gas engines, what would an IAC be? and is it something i can check before a possible jurney to autozone?
Don
Don
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From: Baltimore
On the 5.4L, the IAC attaches to the throttle body and it will be close to the throttle position sensor. The IAC has an electrical connector and a hose attached to it and it will be very near to the throttle plate that opens and closes when you press on the accelerator. The IAC controls the amount of air that is allowed to bypass the closed throttle plate at idle.
The procedure for removing the IAC:
1) Disconnect the connector
2) Disconnect the throttle bypass hose
3) Remove the IAC valve
4) Remove and discard the gasket.
The procedure for removing the IAC:
1) Disconnect the connector
2) Disconnect the throttle bypass hose
3) Remove the IAC valve
4) Remove and discard the gasket.
Tuned
Joined: Aug 2003
Posts: 284
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From: Mena, AR
I have a '98 that started doing the same thing. Ran very rough, stalled at idle, etc. I dug around and found a vacuum hose that had failed at the very back of the engine. It was part of the crankcase ventilation. Turns out this is a very common problem on the 5.4L after several years. I am replacing all the rubber hoses just for good measure. Runs so much better with tight connections. By the way, it was throwing a lean mixture code for both fuel rails.
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New User
Joined: Jul 2005
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I have a 2000 F150 4x4, 5.4 L with the exact same problem as described. I've already changed the gas filter and added STP to the gas tank. The problem persisted. I will look into the IAC tonight when I get home.
Thanks for the info guys!
Gizman
Thanks for the info guys!
Gizman
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From: NJ ... the garbage state
IAC is the Idle Air Control ... in case that wasnt answered. If its bad, i would think it would only effect idle performance, and off idle (eg on the go pedal) shouldnt have stalling if it was the cause.
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So are you saying that IAC should not be the cause of the hestitant when the accellerator was pressed? If not, what do you suggest I look into? I used to work on cars a long time ago when everything was simple, now they added computers and the whatnots. It irritates me when they put in stuff that forces people to take it in the shop. I refuse. I like to fix anything myself. 
Freshman User
Joined: Jul 2005
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The symptoms you had are the same whether its a Ford 5.4 or a Honda 1.6L motor. Hell even my old Mitsubishi motor did it when the Idle Surge Controller died. Annoying as hell and no warning for when it will happen.
New User
Joined: Jul 2003
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From: Texas
I have the same problem with my 1998 5.4 with 155000 miles. I replaced the IAC, the rear O2 sensor and both front O2 sensors. Auto zone said thats what it needed per the codes.
Guess what it still does the same thing and the engine light is back on again.
I sprayed every7 ruber hose with carb cleaner looking for a leak and couldn't find it. I am now at my wits end. Ford want $100 to just hook it upto thae machine.
Help!
Ted
Guess what it still does the same thing and the engine light is back on again.
I sprayed every7 ruber hose with carb cleaner looking for a leak and couldn't find it. I am now at my wits end. Ford want $100 to just hook it upto thae machine.
Help!
Ted
Moderator
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From: Louisville,Ky.
Ted, Have you cleaned the MAF yet? That will cause a lean code and possibly hesitation. Just spray the wire element's in it with carb or throttlebody cleaner. Let it air dry and see what happens. Those little filiments are fragile so I wouldn't try to wipe them.
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Don't waste your time with Autozone or Advance Auto. Their scanners are generic units which kick out guesses at the actual cause and if you want a real answer you need to find a shop with professional grade diagnostic tools. The generic $100 scanners usually tell you things like crank/cam sensor, o2 sensor and things like that but professional units can actually give a more accurate reading. They can also test the systems as the vehicle is running in order to trace the cause as well as test the o2 sensors.
Also it could even be the EGR valve on some cars but without real testing your just tossing parts at the problem. The parts stores love the generic scanners for that very reason.
Also it could even be the EGR valve on some cars but without real testing your just tossing parts at the problem. The parts stores love the generic scanners for that very reason.