I recently filled up with gasoline (not sure if it is related) approximately 2 miles afterwards the truck began running very rough. It had a loud lifter noise while going up hills and had an obvious miss. The CHECK ENGINE LIGHT came on steady but after a few minutes began to blink.

I had to drive 60 miles to return home and experienced the rough idle the entire time.

I went to autozone where they ran the tester and came up with the following codes....

P0401
P0302
P0307
pending P0113

I was told I needed an EGR which i purchased, replaced and returned to have the code re-read.....this time the only code was P0302

I replaced the plugs with Bosche Titanium with no change in performance or code

I replaced the plug wires...same thing

removed the two coil packs and had them tested...they tested in specs

I replaced the PVC and found a large hole in the elbow hose and replaced that as well.....still no change in performance and code....

I replaced the throtle idle control (this is probably not correct name...its the small canister thing that does both vacuum and fuel..mounted sorta below the EGR)

I swapped injector locations to see if the misfire would move also....nope

I then swapped locations of the two coil packs to confirm that putting them under a load wasnt making it mis....nope

I checked PCV tube to verify not clogged

I switched from Bosch plugs to MotorCraft...code changed.....now have P0302...and pending P0305...and P0401..which I didnt have yesterday with the bosch plugs...

I think that exhausts all ideas but am open to try anything you guys think may be it

I have been dealing with LXman1 who is an amazing source of info and I appreciate your help very much btw

 

so no incredible ideas left?

 

It looks like you are now getting a misfire on cylinder 2 and insufficient EGR flow. Lets tackle the EGR code first.

Some common symptoms are a bad DPFE sensor, blockage in the EGR tube, faulty EGR valve or a lack of vacuum for the EGR valve to open.

Seeing as you have replaced the EGR valve, I would look at the EGR tube first and make sure that it is not blocked with carbon. Also make sure that the DPFE hoses are not split or plugged. Another possibility is that you got a bad EGR valve.

After we get the EGR code taken care of, the misfire might go away.

 

After replacing the egr valve all codes except the p0302 disappeared. I then replaced the wires, pluges, pvc and the cracked pvc hose and for two days the egr did not show as an error. It was after I replaced the new bosch plugs to new motorcraft ones that the egr returned.


By egr tube, are you referring to the pipe that hooks to the exhaust? the pipe that also has two rubber hoses that T off of it and return to the DPFE?

Those two rubber hoses are in very good shape. Other then unhooking the large nut end of the egr pipe and reconnecting it to the new one, I did not check it for clogs if this is the one you are talking about.

Also...when in park the engine runs fairly smooth. If i put it into reverse or drive it then has an obvious miss. If I hold the brake and rev it up to 1500-2000 rpm the miss is pretty bad

 

Ok I finally broke down and paid the $95.00 for the dealer to diagnose the truck....

They say the egr ports are plugged and they believe that the valve in #2 cylinder is damaged...he specifically said burnt....that it would cost $380.00 for him to tear into it to confirm the actual damage...

Could someone please tell me how to clean out the egr ports? and also...if the #2 cylinder is burnt what are the reprocussions of continued driving on it?

The mechanic is expecting it to cost $2,000 or more on the low end to fix it

 

Did anyone have a link that explains cleaning egr ports?


We have had to continue driving the truck since its our only vehicle....if it is a burnt valve should i be expecting to blow the engine? or will it just mean bad performance until fixed?

And one other thing...is the diagnostic showed low voltage on the DPFE...or whatever the egr sensor is called...but they didnt say if it could be a contributing factor or not

 

Here is a useful link that I was given for my EGR problem. http:/www.ford-trucks.com/howto/throttlebodyclean.php[/URL]

I cleaned the ports and problem went away. I would strongly suggest you follow the step about the cruise control cable, it makes things alot easier. I picked up 3 gaskets from the Ford dealer for about $15. Make sure you have the gaskets in hand prior to starting the job. My Ford dealer had to order the gaskets and it took 3 days. Once I had the gaskets, it took about 2 1/2 hours to finish the job.

As for the DPFE having low voltage, various voltage readings are supposed to be low. 4-6 volts are supplied to the DPFE and depending on the EGR needed you will have as low as .2 -.7 volts with no EGR supplied, up to 4-6 volts when EGR is signaled by the computer.

So, clean the EGR ports first and see what that will get you.

Good luck.

 

I think I would run a compression test on #2 and another cylinder, maybe #6, to check and see if you have a burnt valve or not.

By comparing the two cylinder pressures you should be able to tell if you are having problems with valves..

 

I agree that is my next step....looking for a link now on how to do a compression test on this engine

 

How can you replace spark plug wires? There aren't any. You sure replaced a lot of stuff. Sounds like you're one bolt away from a radiator cap overhaul. Have removed the negative cable from the battery to clear the codes? Then drive it again. If all else fails you can go to a dealer and let them diagnose it. Usually dealer computers can go into more diagnostic depth than what's available to other shops.

 

No plug wires on a 4.6?? I wish you would have shared that with the list before I spent $100 on a wire set, a couple hours of my time, several skinned knuckles, and many choice words as I tried to undo the wire looms that were difficult to get to and rethread all the wires I recently changed the plug wire set on my 98 4.6 Expy. If I had known there weren't any spark plug wires, I wouldn't have bothered changing them.

 

As stated in the middle of this thread, I spent the $95.00 to the dealer to diagnose the truck....

Basically they said that the EGR ports were plugged, the EGR Sensor had a low voltage reading...

I am going to clean the ports today using the link that was kindly included above.

Yes there are wires on a 4.6L. It was a bit of a nightmare to replace them with the many clips that had to be unlocked and such.