Hey there guys. i have a 2002 f-150 5.4L magnaflow exhaust, k&n intake, superchips tuner and am having an intermitant miss that seems to be more noticable when damp outside. spark plugs have been replaced in recent history. truck has 115,xxx miles on it. seems like i can "force" it to miss when i apply slight throttle when the truck is in overdrive. the codes i can get to come up always seem to point to cylinder three missfire or left bank running lean. i'm thinking that it is the COP for number three that is messing up. what is all involved with removing a cop. removing fuel lines and such? thanks ahead of time

 

If you're getting P0303 that's a no brainer. These Ford truck engines have three very common problems which Ford has made millions on fixing out of warranty trucks. COPs, EGR system faults and cracked or collapsed rubber hoses which cause LEAN codes due to vacuum leaks. Since you have a DTC on cy#3 you should zoom in on that one as Ford is very conservative about setting misfire DTCs compared to other manufacturers. By the time you get a misfire DTC on a Ford Truck you've been having this problem since before you went to visit grandma the last time and that's been a while. Some people can get the COPs out without removing the fuel rails. Some cylinders are easier than others. The necks on the COPs are flexible rubber so you can bend them any which way once you get the little 7mm bolt out. You can find faulty COPs and injectors by unplugging the connectors one at a time and listening for the idle speed to drop and watching for the engine to shake while the connedtor is removed. This is done with an assistant in the drivers seat/truck in gear/BOTH brakes on FULL/engine revved to about 2K. You pull the connectors off of all 8 COPs and injectors one at a time and plug them back when you finish with each one. If the idle speed drops and the engine shakes while the connector is removed that COP or injector is GOOD. If there is NO CHANGE that COP or injector is faulty and it doesn't make a difference whether it is plugged in or not. This is a shadetree mechanic method, but I've used it for years and it works. If you have P0303 you can zoom in on #3 and forget checking the others by removing their connectors. As far as your lean code you can spray something combustable on all the rubber hoses that have manifold vacuum. When idle speed goes up you've found a leak.

 

Reading the link at the top of this section, (1997-2003 F-150 Frequently Asked Questions) is a great resource full of helpful info on replacing COPS/plugs. It's the forth link down from the top of this thread...

 

Remove the connector to the injector, remove the connector to the COP, remove the one bolt that holds the COP in place - lift the COP upward. done,