Hello Im new to this forum and need some help. I have a 2004 f150 4.6l. I have been having problems with jerking idle and jerking at acceleration. I had it diagnosed and it came up with P0303 code number 3 cyl. so I decided since there is 110,000 miles on the truck that I would change plugs and coils, changed them all and still have the same code and still runs rough, is there any suggestions what else it might be that is causing this, very frustrated!

Thanks for your help
brian

 

Take one of the old coils and spark plugs, hook it to the coil connection, grounding the threaded area and see if it sparks when running. If it does, the injector is where I'd look. Have you checked the vacuum reading or compression?

 

I will try that and post. I have not done a vacuum or compression reading as of yet

 

That code sounds familiar, i had that on my truck i beleive. It was a cam phaser sprocket.

 

It's as easy as going to Google.com, and typing in "P0303" in the search box...

Here's a link from that search:

http://www.obd-codes.com/p0303

Here's what it says as possible causes:

A code P0303 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

 

Hey [MENTION=38002]kayaker[/MENTION] did you ever fix the problem? I have a 2005 F150 5.4l and its doing the exact same thing. I plan on changing the plug and coil, but you say that didn't work. Did you ever fix the issue?