I have a 08 Ford Expedition with a 5.4 L engine. Recently I changed all spark plugs and the fuel filter and now the engine is not running smooth. I had the fuel pressure checked and is 60 before start and 70 while idle. Is this normal? I should mention that the old spark plugs were bad and so was t…

No check engine light on and use the OEM plugs.

Check for vacuum leaks. Make sure you didn’t upset some hose or connection when you did the plugs.

Don’t take this the wrong way, please are you sure all the spark plugs are tight and down all the way? If the threads in the head are buggered up, the plug will seem tight, but it won’t be down all the way On this application, you have to remove the coils. Are they all plugged in correctly? How…

Thank for all the suggestions. I should have mentioned that the tune up was a result of intermittent problems while driving long trips. When accelerating uphill the engine would feel like is losing power and then I would hear a strange sound that dissappear as soon as I take my foot of the gas. This…

@al78 By chance, does this engine use those mile long spark plugs? You’ll remember them, if this is the case, because of the length, and the strange electrode design Did you have a difficult time removing the plugs? Was the coil boot black in color, as opposed to brown?

db4690 no black color Yesterday I had a friend check my work and he took all spark plug out and put them back checked all wires still running rough Tester thanks for the specs, this means the fuel pressure might be too high since on running it goes over 70. Is the regulator in the fuel pump or som…

@al78 I’m not sure if I explained myself very well, earlier By black in color, I meant this . . . are the rubber boots on the ignition coils black in color, as opposed to brown in color? I didn’t actually ask if the plugs are black, which would have indicated a rich condition Since you were appa…

These were regular spark plugs, initially the store gave me the long ones but I had to go and have them changed. Based on what I have is it safe to say that I have to change the fuel pump?

In my opinion, the fuel pressure is within specs According to my information, fuel pressure is supposed to be 35-70psi key on engine off I’d be very hesitant to recommend a fuel pump replacement, especially because I don’t have the truck in front of me

08 Expedition 5.4 L fuel pressure

Maintenance/Repairs

Tester August 27, 2015, 12:04am 8

The fuel pressure spec for your engine is:

Key On Engine Off…35-45 PSI

Engine Running…62-69 PSI

Tester

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08 Expedition 5.4 L fuel pressure

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