i got a misfire on cylinder 1 at idle not all the time but every now then but the truck idles a little rough ive cleaned the maf sensor,cleaned the throttle body,cleaned the iac valve, i replaced the coil (motocraft),plugs (motocraft), and wires they aint motocraft i thought about goin back and getting motocraft wires and i put techron fuel system cleaner in it and stp injector cleaner but as far as the insuffient egr flow goes ive replaced the dpfe sensor, egr valve, egr solenoid what else could it be??? maybe vacumn leak in a hose? or some other sensor??

 

I recommend going with the MC wires. The 4.2l only like MC everything. Trust me, I know!

I've had 2x 4.2l's and a 3.8l (pretty much same engine). All three of them only liked MC plugs, wires, and parts in general.

To be honest, the prices really aren't that much different, and you are guaranteed they will work without issues.

 

Look in the corner of the engine bay behind the battery tray. There is a bundle of vacuum hoses that go to a canister of some kind inside of the right fender. One of these hoses goes directly to the EGR Solenoid. On my truck, the hose was broken. It is an easy fix, but you have to find it first. High on the firewall there is a monument where the electrical system has several branches that are bolted together. Straight down from this monument (electrical bus) is a bundle of vacuum lines. There is a block of four lines, one of the lines is white and goes directly to the EGR solenoid, next to the DPFE sensor, and when the solenoid is turned on, the vacuum goes to open the EGR Valve, but the vacuum is low so you get insufficient flow, P0401.

 

is it under the battery tray or to the right of it

 

Behind the battery. Remove the battery to get at it.

 

alright ill check it out tommorow thanks

 

i checked the hoses and they all looked good

 

There is a white hose in that bundle, it goes to the EGR Solenoid. Vacuum goes to the solenoid, the solenoid is energized and the EGR valve is activated. The DPFE measures the difference in the pressure on both sides of the orifice in the tube that connectes to the EGR valve on one side and the exhaust manifold on the other. If the white hose has a hole, then the solenoid will not pass vacuum to the valve, and the EGR efficiency will be low. I had a P0401 code, and it took weeks for the Readiness Monitor to come to ready, or for the code to come up again.

Youtube has a good test procedure to check the components. You can have all good stuff by the diagnostic procedure, but the procedure does not test the integrity of the white hose. To perform the tests, you will need a vacuum pump. You can get one of these at the auto parts store. AutoZone has a tool rental program where they rent you tools for free. You buy the tool, then bring it back later for a full refund.

 

My bad. I've been telling you about the 4.6L Triton V8. I'm sorry. I might have given you a bum steer.

 

I've done that too. It happens... lol