I have a 99 F150 4x4 with a 5.4l with 178,xxx miles on it. Truck runs great. It just starts a little hard at times. You have to crank it over a few times before it will fire and then sometimes it will fire a couple times and crank it a few more times and it will take off. Then other times you just bump the key and it fires right up. The check engine light was on and I had a P0171 & P0174 code. I narrowed that down by a homemade smoke test to a back PCV elbow on back of intake. Replace the whole PCV assembly line with Ford OEM part. Took throttle body off and IAC and cleaned both. Put back together and codes are gone. Gas milage is a little low at 12 but think that was due to the vacuum leak in PCV. I am just wanting to get some more thoughts on what could make it be starting hard? I'm not sure how long its been since the plugs have been changed as to we got the truck with 170,000 miles on it but that is my first thought is they are due. But before I tackled changing them I just wanted to get some more opinions. Any help would be appreciated! Thanks!

 

Well your pulling at straws now.
There is a specific cold starting operation that goes on.
How does the computer know it's to be a cold start vs a hot restart?
Here is how it knows;
1. Key to Run before cranking, the PCM looks at the resistance values of the intake air temp sensor and the cylinder head temp sensor to tell. It's the only way is has, to tell.
2. The fuel pump runs about 1 second then shuts off.
3. Fuel injection amounts are increased.
4. Ignition timing is advanced.
5. Intake air control is increased for added air and higher idle.
6. Fuel pump restarts full time when you crank the motor..
And you thought it was simple.
If any of these parameters are faulty in some way cold starts become difficult.
.
First, check cold fuel pressure with a gauge by cycling the key to run several times to build pressure. Look for about 35 psi +/-.
It's not the air meter, Ox sensors or other parts if the truck runs otherwise.
Be sure there is no water in the gas.
Be sure the IAC is not sticking closed from the last time the tuck was driven.
Leave everything else alone for now.
Good luck.

 

I am going to change the fuel filter. Was going to the other day and didn't realize that you have to have the special tool to get the lines off. I am going to run some seafoam through it and check the fuel pressure this weekend. I imagine the spark plugs are due to be changed that is in the near future anyways.