well the truck is a 99 f150 xlt with 4.6, The original problem was EGR valve insufficient flow, so I removed the throttle body and cleaned EGR port holes which were plugged solid, still getting the same reading, check the vacuum line and there is good vacuum, when I pulled off the vacuum line while the truck was running it did not make a difference in the way the truck was running, now when the truck is cold it runs like crap, once at running temp it smooths out and runs great, any help would be great.
Thanks

 

Your post indicates your a bit mixed up about the EGR system operation.
Pulling a hose off won't make any difference because the EGR is not open for there to be any effect.
To check the EGR path, you would need to put a small amount of vacuum on the hose to the EGR so it 'opens' a small amount.
Doing this lets a small amount of exhaust gas into the intake.
It has an effect on idle quality and indicates the path is open and the EGR seals when closed and will respond to a vacuum signal from the regulator when commaned by the computer to open.
Then next part of the system is the DPFE sensor.
This measures the flow accross a small orfice in the metal tube.
If it measures a low flow on two sucessive tests, the 401 code is set.
From this you can see how to test the EGR flow manually.
If all responds correctly, the DPFE sensor could be suspect if it cannot report the flow test results to the computer.
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As for poor running before warm up, you may have an additional seperate issue to be found such as a faulty cylinder head temperature sensor, thermostat not opening, poor OX sensor performance etc.
Here is how cold start is handled:
At key 'on' the computer sees the coolant temp value and the intake temperature value.
This sets up the fuel tables to be rich for fuel same as a choke on a carb.
It opens the IAC for extra air that also raises the idle speed same as a fast idle cam on a carb would do.
The ignition timeing is also changed.
About 45 seconds into a start, the OX sensors heat enough with exhaust and their own heaters to begin to respond to the oxygen in the engine exhaust and take over feed back control of the fuel injection from that point on.

.
With two possible issues it may be causing you to run them togather as one fault causing confusion.
You are dealing with a fully computer controlled system and must be delt with in that fashion.
Good luck.

 

Thanks for the info, I'am going to try the manual test with the EGR and go from there, Thanks again.

 

well, I put vacuum to the line going to the EGR and the engine stumbles not sure what my next step should be?

 

You got the correct response with fault free EGR hardware.
I would consider replacing the DPFE with a Ford only part.
.
Refer back to the DPFE discription above. If the sensor is faulty it can't report the test results even though the flow may be correct.
Good luck.

 

Thanks again! I will tackle the DPFE tomarow,I did change the T stat still runs ruff until I drive 5 miles or so then smooths out?

 

update, replaced the DPFE fixed that problem, now the truck cold or hot runs rough and there is no CEL yet, had it scanned at autozone and it came up o2 sensor pending any thoughts ?

 

At this point,the OX sensor pending may be old history.
An Ox sensor usually does not cause rough running because they only report the Oxygen levels in the exhaust gas to in turn control fuel injection amounts.
Even disconnecting them would not cause undo driveability issues except poor fuel mileage and codes.
My suspect is the EGR may be allowing exhaust gas back into the intake.
When this happens the motor will get rough from a lean mixture, advanced ignition timing and a cut back in fuel as a normal reaction to a leak.
Take the EVR solenoid off.
Remove the round cap and clean the filter.
Clean the internal body as well.
This is a 3 port device even though it has only 2 hoses.
The third port is through the filter. When the EGR is commanded to close, it need outside air through this filter to allow it to close up quickly.
If not, the EGR will be slow to close and cause driveability issues.
Work on clearing the the rough running first then clear the codes out to see if any come back.
Good luck.

 

ok cleaned EVR ran truck and made no difference, did find a calapsed hose at PCV changed that out now it seems that the rough running is intermitant, runs rough at idle and OD it is not as bad as it was?

 

Did you disconnect the battery before replacing any sensors?

 

I did not diconect the battery before I changed the sensor, I did after to clear previous CEL.

 

Well seems as though the EGR issue is solved, still have a miss CEL came on and code was p0308 so I changed the plugs and used autolite's gapped @ .052 running smooth again, but there is still an occasional miss most noticeable in over drive, any ideas what this could be ?

 

The peticular miss condition is often a low output coil.
In OD and light throttle, the EGR is commanded open.
This makes the air fuel ratio very lean and requires the coils to output near their maximum voltage in reserve.
If one cannot fire a cylinder reliably you feel it as a 'skip' type of missfire.
Since it comes and goes with driving conditions, no code is set such that you don't know which cylinder it is.
Either by sub or a dealer stress test is about the only way to find which coil is the cause.
If you try to wait it out to become a hard failure that will set a code and tell which cylinder, you may wait a long time and have to put up with the driveability issue it causes.
Good luck.