Transcript Ford DPFE EGR System

The Whole System
The Whole System
Ford DPFE EGR System
1.
vacuum
applied
2. Pintle opens
3.
EXHAUST GAS FLOWS
No Electronics at the Valve
Ford DPFE
•Differential (Delta) Pressure Feedback EGR Sensor
•Detects EGR Flow
Note Tube
connections
“REF”
Valve open
Valve closed
DPFE Basic Schematic and Sensor Data
EGR Vacuum Regulator (EVR)
1. EVR Regulates vacuum to EGR
2. Controlled by PWM to open and close EGR valve.
3. As duty cycle increases, EVR increases vacuum to EGR.
4. EGR opens at about 40% duty cycle.
5. Note “filter” is where vacuum bleeds
EGR Vacuum Regulator (EVR)
Normally Bleeds about 1”Hg of Vacuum
With Solenoid at 100% duty should output about 7”Hg
Vent through filter cap
Basic EVR Schematic & Spec
VPWR = Battery voltage
ORIFICE TUBE
Tube feeds exhaust gas to EGR valve
Requires no maintenance
DPFE measures pressure drop across metering orifice
Ford DPFE EGR System
Diagnostics
•KOEO self-test: Checks for DPFE sensor out of
expected range (Pass codes here indicate DPFE & EVR
circuits are in expected range
•Continuous Memory: Stores any intermittent faults
•KOER self-test: Functional test of DPFE, EGR Valve,
and EVR (Pass codes here indicate EGR system OK)
•DPFE Scan DATA .55V to 1V with valve closed
KOEO Circuit Checks
DPFE sensor is tested for out of range values (typically >4.96 volts, <0.195 volts) and if this is
detected the DTC P1400 or P1401 is set.
EVR Output circuit is checked for opens and short using the internal smart driver in the PCM,
and a failure records P1409.
KOER Idle Valve Stuck Open Test
•PCM checks DPFE voltage and compares it with last KOEO DPFE voltage state
•If voltage is different this indicates a exhaust gas flow is present at idle
•PCM stores DTC P0402 EGR Flow Excessive Gas Detected
•(EGR poppet (pintle) valve has stuck open (false DTC sets if tube leaks)
KOER Hose Test
•During acceleration (or KOER test), PCM commands EGR closed
•PCM checks DPFE signal for a voltage consistent with zero flow
•A DPFE voltage difference during acceleration with EGR shut indicates a hose fault
•P1405 DPFE sensor Upstream hose off or plugged
•P1406 (or P1401) DPFE sensor Downstream hose off or plugged.
Functional Flow Checks (gas restriction or DPFE signal incorrect)
•Cruise speeds, PCM checks EVR duty verses DPFE sensor voltage
•If EVR duty is too high, there is insufficient gas flow
P1401 EGR Insufficient Gas FLow detected (with EVR above 80%)
(1401 also: possible sensor, open in VREF or down steam hose off)
P1408 EGR Flow out of self-test Range (KOER self test, not Monitor)