Rajczak Posted January 31, 2010 Share Posted January 31, 2010 I have (OK...my wife has) a 2003 Expedition with a 5.4L (120,000km) that runs great except for one issue. When warmed up, and stopped in drive (or reverse) it runs rough. It otherwise runs fine, idles in park fine, drives great! Gas usage isn't affected. Any help would be appreciated. Thanks all in advance! Karl & Lisa Quote Link to comment Share on other sites More sharing options...
Ron W. Posted January 31, 2010 Share Posted January 31, 2010 First thought the Idle air control valve or IAC, diamond shaped mounting base 2 small bolts and one electrical connector. Is your check engine light on - does the check engine light work - any codes? 1 Quote Link to comment Share on other sites More sharing options...
Rajczak Posted January 31, 2010 Author Share Posted January 31, 2010 The check engine light works, but isn't on....and I don't know how to get the codes. I'll have to take it to the dealer for that I imagine. It may be a coincidence, but this started happening after sitting outside in a snow storm, then being brought in to thaw out in the garage. Quote Link to comment Share on other sites More sharing options...
theDuff Posted January 31, 2010 Share Posted January 31, 2010 I assume your check engine light is on? Sounds like a vacuum leak. With the engine running at idle, pop the hood and listen for a loud hiss (not a soft one, the intake naturally has a kind of hiss sound, especially when you goose the throttle). Follow the vacuum line that starts at the pcv valve on the passenger side valve cover and leads to the rear of the intake manifold (it might also tee off to the upper intake elbow). Its a hard plastic line with thick rubber connections. Inspect every rubber connection for any collapsing, holes or tears. There will be oil residue in all these connections. If you find any problems at all go to your neighborhood ford dealer's parts department and replace the entire thing. Do NOT try to repair it. They should have it in stock . Your pcv valve is probably original and it probably needs to be replaced anyway and should come with the new tube. If it doesn't, get one. This is a fairly simple repair you could do yourself with very simple tools and save yourself some cash, just put it back exactly how you found it routed. To ease installation you can mist a little wd-40 on the rubber connections. If all this looks great it could be bad intake gaskets, ignition coils, or anything, and you should go to the dealer and have it checked out. 1 Quote Link to comment Share on other sites More sharing options...
Rajczak Posted January 31, 2010 Author Share Posted January 31, 2010 The check engine light isn't on & I have checked all the vacuum lines/connections, and they all appear fine. As well, no vacuum leak is audible. Hopefully it isn't the intake gaskets! Anyway, I will change out the PVC valve, as I am not sure of it's age, and go from there. Thanks again for your time, I appreciate it. Quote Link to comment Share on other sites More sharing options...
Ron W. Posted January 31, 2010 Share Posted January 31, 2010 The check engine light isn't on & I have checked all the vacuum lines/connections, and they all appear fine. As well, no vacuum leak is audible. Hopefully it isn't the intake gaskets! Anyway, I will change out the PVC valve, as I am not sure of it's age, and go from there. Thanks again for your time, I appreciate it. If I remember correctly the IAC being dirty or worn out will not set a code. If you have a vacuum leak and you stated the CEL works you'd have a code, but sometimes a code will be stored even without the CEL flashing. You can go to almost any parts store and buy a scan tool - I'd raccomend one that stores / shows "pids". The OBD2 connector should be under the dash just to the right of your steering column. Investing in a scan tool will pay for itself in the long run. As far as changing the PCV go to your local Ford dealer and buy the pcv and tube assembly Ford base number 6C324 I beleive. Most common vacuum leaks on the 5.4 are caused by the 90% rubber elbows used on the PCV tube, second would be the tube from the VMV (vapor management valve) on the firewall to the intake. Good Luck 1 Quote Link to comment Share on other sites More sharing options...
darrellblackmore Posted November 1, 2014 Share Posted November 1, 2014 If I remember correctly the IAC being dirty or worn out will not set a code. If you have a vacuum leak and you stated the CEL works you'd have a code, but sometimes a code will be stored even without the CEL flashing. You can go to almost any parts store and buy a scan tool - I'd raccomend one that stores / shows "pids". The OBD2 connector should be under the dash just to the right of your steering column. Investing in a scan tool will pay for itself in the long run. As far as changing the PCV go to your local Ford dealer and buy the pcv and tube assembly Ford base number 6C324 I beleive. Most common vacuum leaks on the 5.4 are caused by the 90% rubber elbows used on the PCV tube, second would be the tube from the VMV (vapor management valve) on the firewall to the intake. Good Luck I had this same issue twice now and it's been the VMV on the firewall both times Quote Link to comment Share on other sites More sharing options...
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