I've got an '05 with 100,000 miles, 5.4 auto. Xcalibrater tuner, Magnaflow single exhaust, AirForce One intake.
The other day right after I filled up at Shell, I noticed the idle just didn't seem quite normal. When I got to work I shut it off and a couple hours later I went to start it and I had to keep cranking on it to get it to start. Then the CEL came on.
The four codes were:
P0171-System too lean (Bank One)
P0300-Random misfire detected
P0307-Cyl #7 misfire detected
P0308-Cyl #8 " "
I put a bottle of heat in the tank and drove 50 miles home but it didn't help. I replaced the fuel filter, which was very dirty inside ( I cut it open ). Cleaned the MAF sensor with Elec. Contact Cleaner, and filled up with premium at another station. Still didn't help.
It seems like it does this only when the motor is cold, but fires right up when the motor is hot. The truck runs just fine down the road.
This morning after it had been sitting all night, I turned the ignition on and waited a little longer this time before I began cranking, and it fired right up.
Could it be the fuel pump? Is there an easy way to check the fuel pressure?

 

Have you changed the plugs? IIRC they need to be changed at 100k.

 

No, the plugs are still factory original. I've been dreading that job.

 

I can't seem to find P0171 and PO307, but will keep looking.

P0300-
P0308
P0320
P0340
P1351-
P1364 Electronic Ignition (EI) EI system concerns EI system has a malfunction which may cause a transmission concern. Harsh engagements and shifts, late WOT shifts, no torque converter clutch engagement. Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

At least you got some codes, where they can go from there, best of luck to ya.

 

That sounds like the same thing that happened to me. I have a super chip in my truck. Try selling your computer back to stock drive it a little and then put it back to the setting you had it on before. It worked for me, hope it does for you too.

 

A P0307 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #7.


SymptomsSymptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
CausesA code P0307 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
Possible SolutionsIf there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

You may the dreaded fuel injector in # 7 going bad. I sugest you take it in to dealer and get it diagnosed.

 

Boy, thats a pretty good list you have there 007. Can you tell me where the schrader valve is? There's nothing on the fuel rail.

 

As far as I know the rail doesn't have a schrader valve anymore. Has a
fuel rail pressure and temperature (FRPT) sensor. Measures the fuel pressure and temperature and sends these signals to the PCM.
uses intake manifold vacuum as a pressure reference. I believe you can disconnect the sensor to relive pressure in the fuel system when you crank it over until the engine dies and probably set another code, but don't think you would need to do this because most pressure will bleed off overnight, if so, hook it back up, cycle a few times and it should be fine. I know i used to like hooking up a pressure gage the the valve and check fuel pressure years ago. Not now as far as I know, it all goes to the PCM.

I'm assuming you have a 2005 f-150 w/5.4, if wrong, my bad

 

Sounds like a new set of Plugs & Cops to me!...........

 

I don't know, it kind of seems like a fuel thing. If I leave the key on for 5-10 seconds before I start cranking, then it fires up.

 

I really think you need to get your truck to the dealer and diagnose the codes, they can do wonders and save you $ installing parts not needed. You can throw a whole lot of parts at it with nothing to gain. But that's why they have the tools to properly diagnose the problem. I used to work on Mercedes, and you couldn't even Begin to fix something without the laptop, unless you've been there before. Take it to shop you can trust. With 100,00 miles plus on it, I'm sure spark plugs would be #1 if not replaced earlier. Then go from there.

 

My dads truck has the same symptoms. Cylinder 1 misfire P0301 and a P0316. P0316 means a misfire was detected on start up. Quintin said it sounds like a stuck injector for the #1 Cylinder. I cleared the codes and they have not came back. Truck started better for a day or two and then the hard start came back but not the CEL. He hasnt taken it to the dealer yet. Here is the thread that I started.
https://www.f150online.com/forums/sh...81#post3110981

 

Could it be a stuck injector that is closed on two cylinders? Or possibly it is 1/2 working and just about ready to fail?

 

#7 injector it sounds like, could be wrong though, hard to diagnos on-line

 

True... I've seen this before, where the injector malfunctions and it's like on the verge of going... and this is the tell-tale signs.

Maybe it's a good idea to check them anyhow, before you end up with a gas filled cylinder and create a hydrolock on the engine.

One of them might get stuck open and dump a whole lot of fuel in.