tktiger

I had a check engine light and the code said change EGR valve. The truck was running perfect before changing.
Now when I slow down to a stop and it stalls at idle.
I did:
After changing the EGR and the DPFE, blowing out the vacuum lines and the silcone hoses from the exhaust to the DPFE, and checking all connections it still is stalling.
Any ideas?

Good old Bill

You didn't tell us the year and engine. Backyard fix, put old parts back on and see what happens. May be one of the parts is defective.

torkum

Most likely your EGR is stuck in the open position or your DPFE is foobared. I've never heard of someone cleaning a DPFE so I would say it's the new problem. Remember the EGR functions are mostly performed at idle.

Just call me Sean

iTrader: (1)

No no, there is virtually no EGR function at idle. The EGR is active during part throttle and cruise conditions.

Good old Bill

I'm with you Sean, wonder what Torkum had on his mind.

torkum

I stand corrected, was thinking about base PCM testing and monitoring of the EGR/DPFE that is done at idle. This might help explain why I think his EGR is stuck open [from the Ford Shop Manual]: don't know why all the points are showing up as 1s, when posted they show as 1-5.


Exhaust Gas Recirculation (EGR) System Monitor—Differential Pressure Feedback EGR Exhaust Gas Recirculation (EGR) System Monitor—Differential Pressure Feedback EGR
The Differential Pressure Feedback EGR System Monitor is an on-board strategy designed to test the integrity and flow characteristics of the EGR system. The monitor is activated during EGR system operation and after certain base engine conditions are satisfied. Input from the ECT, CHT, IAT, TP and CKP sensors is required to activate the EGR System Monitor. Once activated, the EGR System Monitor will perform each of the tests described below during the engine modes and conditions indicated. Some of the EGR System Monitor tests are also performed during on demand self-test.

1. The differential pressure feedback EGR sensor and circuit are continuously tested for opens and shorts. The monitor looks for the Differential Pressure Feedback EGR circuit voltage to exceed the maximum or minimum allowable limits.
   
   The DTCs associated with this test are DTCs P1400 and P1401.

1. The EGR vacuum regulator solenoid is continuously tested for opens and shorts. The monitor looks for an EGR Vacuum Regulator circuit voltage that is inconsistent with the EGR Vacuum Regulator circuit commanded output state.
   
   The DTC associated with this test is DTC P1409.

1. The test for a stuck open EGR valve or EGR flow at idle is continuously performed whenever at idle (TP sensor indicating closed throttle). The monitor compares the Differential Pressure Feedback EGR circuit voltage at idle to the Differential Pressure Feedback EGR circuit voltage stored during key on engine off to determine if EGR flow is present at idle.
   
   The DTC associated with this test is DTC P0402.

1. The differential pressure feedback EGR sensor upstream hose is tested once per drive cycle for disconnect and plugging. The test is performed with EGR valve closed and during a period of acceleration. The PCM will momentarily command the EGR valve closed. The monitor looks for the differential pressure feedback EGR sensor voltage to be inconsistent for a no flow voltage. A voltage increase or decrease during acceleration while the EGR valve is closed may indicate a fault with the signal hose during this test.
   
   The DTC associated with this test is DTC P1405.

1. The EGR flow rate test is performed during a steady state when engine speed and load are moderate and EGR vacuum regulator duty cycle is high. The monitor compares the actual Differential Pressure Feedback EGR circuit voltage to a desired EGR flow voltage for that state to determine if EGR flow rate is acceptable or insufficient. This is a system test and may trigger a DTC for any fault causing the EGR system to fail.
   
   The DTC associated with this test is DTC P0401. DTC P1408 is similar to P0401 but performed during KOER Self-Test conditions.

tktiger

Details of the engine.
Put a second (new) DPFE on and have the same problem.
Issue happens when you slow down from speed to stop, as the truck begins to idle it races a bit and then dies.
When restarted it races and dies - may stay running if lucky.
Should I
A) Replace the new EGR with another one (I don't have the old one - turned in for warranty $$)
B) Pull out the exhaust pipe that ties into the EGR and clean it out? (already blew it with air but may not have cleaned the carbon)

generalmotor

check to make sure you didnt accidently leave some vacuum line off back there that could cause the racing and then dying

torkum

Try cleaning the IAC.

Mr B

Torkum I wish I knew half as much. Thanks. If the solenoid is fubar and stuck would it throw that code because it sounds like maybe a partial vacuum malfunction to me. I was under the impression that the EGR solenoid was basically an on or off vaccum switch to the EGR valve.