EGR flow issues- where do i go from here?

[airline tech]

I am in the process of a very detailed description of the system and still fine tuning it, as your readings and another members readings (EGR System)

I want to know at KOEO and IDLE -- Compare
I want to know how much these readings change between the 2

The Following: PID Readings
BARRO: (Pressure)
MAP Press (PSI)
MAP Press (Voltage)
Exhaust Press Sensor (Pressure)
Exhaust Press Sensor (Voltage)
DPFE (Press)
DPFE (Voltage)

I know you do not have a DPFE Voltage PID - so with the connector connected and at KOEO you can (Back-Probe) the Signal Return & Signal Wire - and when connected to a meter this will show what the voltage display (should be) on the scan tool.

Ford Spec for this voltage is 1.3 to 1.7 Volts which also equals the -0.30 to +0.30 PSI Reading you have and at KOEO this reading should be STABLE, and this reading also should remain stable if it is reading - the sensor is programed to read - True 0 (Centered) however has the tolerance zone above- (True actual (0) is the goal to be at) or just slightly below such as (1.48 Volts or -0.06 PSI)
So, for REF: 1.5 Volts and (0) PSI is what the sensor should be reading at KOEO and the PCM slightly biases the sensor negative by a small margin.

Since you have confirmed that - with disconnecting the hoses - the reading remains the same then this rule's out tube blockage as throwing the reading off (KOEO Test-Only)

I also need a second confirmation from you on your DPFE Voltage reading you had:
5.04 Volts or 5.40 Volts with meter.

During your drive tests record the above PIDs plus the following

EGR Valve Position Desired
EGR Valve Position (Actual) or (Flow)
EGRT - EGR Temp (Degrees)
EGRT - EGR Temp (Voltage)
Throttle Position (Percent)
Calculated Load or Actual Load (Percent)

It also would be helpfull to get a PID Reference of (ALL) Temp Sensors on a cold engine:
Ambient
ECT
CHT
IAT
IAT 2

The EGR valve does not (APPEAR) to be opening, and it should be but is being disable by the sensor readings that control it.
The goal is to find which one is (Off)

I am wondering if the real issue is in the VREF circuit on the DPFE as that is where so far - the reading is out of (normal) but however in (Tolerance)
and for me - it would be the VREF Reading (Voltage)

Just in case the PCM has the sensor (Bias) locked into a learned - status of normal (0) try running a PCM Self-Test and or disconnect the battery for 10 minutes or so.
The backprobing and seeing the actual voltage reading on the DPFE signal wire will reveal it.
is it in spec - 1.3 to 1.7 volts at KOEO and stable

As I stated - I am in process of putting together a very detailed system operation

So, provide what you can on the PID Data and I can use that as a guide to see if I note something else that is out of normal specs at this point its the DPFE VREF Circuit as the source of the issue.

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[airline tech]

I had a subscription to Forscan that ran out, although it will let me run some limited diagnostics. I scanned it for codes and it had none in the PCM module. Only a code for a TPMS tire in BCM
I ran the KOER self-test and it picked up code P1116:00 Engine Coolant Temperature Sensor out of range .This is the first time I have seen this code and maybe the other scanner did'nt pick it up?. Could this possibly be related? I am goint to clear it and see if it comes back

YES- This is a Tie IN

VREF: Circuit: 5.0 Volts
Fuel Rail Press Sensor
DPFE Sensor
Oil Press Sensor
MAP Sensor

VREF Signal Return:
ECT - Eng Coolant Temp
CHT - Cyl Head Temp
DPFE - Sensor
EGRT (Temp)
Ex Pressure Sensor
HO2S-12 (Rear O2 Sensor)

This may explain the higher VREF voltage and your negative bias on the DPFE

 

[afbryant]

I will see if I can run live data tomorrow with Forscan just to see what they read. I will looking at coolant temp sensor a little closer. I am sure I will be changing it. Wow, this has been an adventure. Thanks, I will post results. It will be a while. Feels like Alaska around here

 

[airline tech]

I got the Rock Auto DPFE sensors last week and I put on on and have driven it around 400 miles since. I tested it while connected without the hoses and it read -0.004 without much fluctuation.(KOEO)

I have been running live data most every drive and the demanded and actual EGR readings remain a 0. Neither PIDs never leave 0.
"Desired Position of Exhaust Gas Recirculation (EGR) Valve" and
"Position Sensor A Of Exhaust Gas Recirculation (EGR) Valve -Corrected Linear Lift Position" These Standard DPFE sensors from RA look basically the same as the OEM Ford sensor with FoMoCo rubbed off. The DPFE sensor reading is fluctuating -0.36 to 0.39 with the higher number at brief WOT higher RPMs.

This is getting confusing. This truck is actually running as smooth as ever since I put this RA sensor on. I have checked for codes several times after driving this week but it has NO codes. I don't know whether to trust this scanner or this new sensor, but the scanner was reading the EGR demanded and actual readings fluctuating on the OEM DPFE sensor. I tried again to get the scanner to open it manually, but it is not compatible with this demand.
To be sure , the truck would throw codes if the EGR valve was not actually opening, right? I am going to put in the other RA DPFE sensor on if it ever warms up around here.
Cheers guys

Sorry I missed that it went to normal in your first paragraph- I only saw the negative numbers -0.36 , so now at koeo you have a normal reading , what does it read at idle? Same or the high negative numbers - if it moves to high negative numbers it’s the Tube restriction that’s causing the issue. Something is restricting the equal pressure on each side of the orifice - most common is the smaller port on the tube (The Downstream) pressure ref port being that you have cleaned it as best you can then the issue is in the orifice itself which is in between the small and large ports on the tube.
As I said I missed that the reading moved to a normal reading at KOEO, this is a key factor here. If it still reads high negative at KOEO then yes it’s in the circuit and I am going bet it’s in the signal return , driving the higher than normal VREF voltage reading you have up. I suspect every sensor on the signal return is slightly biased negative of normal.
The best thing to do (if circuit) related is to meter the VREF circuit or use the DPFE pressure PID as a ref , and disconnect every sensor on the Signal Return- and note which sensor causes the circuit to shift back to normal- That would be the problem sensor - as far as the CHT , we do not know if it’s the sensor or is it just the only sensor that is picking up and faulting a bad signal return circuit.
So removing each sensor from the circuit one by one may help isolate (if it’s a sensor) repeat the process for the VREF feed the same as the signal return.

 

[airline tech]

Sorry forgot to add - plus a correction, I noted CHT and meant ECT as the sensor reading coded.
What I believe is happening and why the issue returns, the tube is clogged and the DPFE diaphragm is being held in the max pressure position for so long it damages the diaphragm- and locks it in place - this is why your old sensors (x4) are all reading negative- you installed the new sensor - reads normal at KOEO and off off spec at idle - eventually it going to do the same as the previous sensors , if I am correct and you actually had a good reading at first - it’s a clogged tube that is producing your issues.

 

[afbryant]

"I want to know at KOEO and IDLE -- Compare
I want to know how much these readings change between the 2"

The Following: PID Readings KOEO / IDLE
BARRO: (Pressure) --- 14.6 PSI / 14.6 PSI
MAP Press (PSI) --- 14.6 PSI / 4.2 to 4.8 PSI
MAP Press (Voltage) --- 1.55 V / 0.45 V
Exhaust Press Sensor (Pressure) - 14.9 PSI / 14.8 to 15.1 PSI
Exhaust Press Sensor (Voltage) - 1.02 V / 1.02 to 1.04 V
DPFE (Press) --- -0.00 PSI / -0.00 PSI
DPFE (Voltage) --- 1.5 V / 1.49 to 1.50 V

I had to go buy a laptop so I can now use Forscan. Cut out "some" of my confusion.

"It also would be helpfull to get a PID Reference of (ALL) Temp Sensors on a cold engine:"
Ambient
ECT
CHT
IAT
IAT 2 "

Engine Coolant Temp----48*F
Ambient Ait Temp----48*F
Cyl Head Temp -----50*F
Intake Air Temp (IAT) 48*F
Intake Air Temp Bank 1 sensor 1 (IAT11) 48*F
Intake Air temp Bank 1 sensor 2 (IAT12) 50*F
Intake Air Temp Bank 1 sensor 3 (IAT13) -40*F negative
Intake Air Temp Bank 2 sensor 1 (IAT21) -40*F negative

I I took the connector off the DPFE sensor and checked it again with the meter and it is 5.03 to 5.04 V, not really much fluctuating. Also the same to ground
I have not driven it to record the PIDS yet but I will as soon as I can. Thanks ,
Allen

 

[airline tech]

Everything Looks Normal - So Far

ok for a test drive:
Use The Following PIDs:

Barro:
EGR Desired:
EGR Actual - Variously Labeled
(May be labeled as EGR Valve Position Sensor A (Lift Position) Corrected) or (Flow Area or Duty Cycle Position)
DPFE Pressure:
DPFE Voltage:
MAP (Hi Resolution): This is the one the PCM actually uses for (PCM Inputs)
MAP (Pressure):
MAP Voltage:
Calculated Load or Actual Load - Variously Labeled:
Ex Pressure Sensor (Pressure):
Ex Pressure Sensor (Voltage):
Ex Gas Recirculation (Temp) - EGRT:
Ex Gas Recirculation (Voltage) - EGRT:
Engine RPMs:
Vehicle Speed:

Hopefully you can view frame by frame of the recording - Note: A EGR Event is only about 2-Seconds - Open and Closed - and it may be that your scan tool may not be able to (pick it up - refresh rate)


I am still working on my (ref data) and have a number of Live Data - Drives to put into a chart format for easier views vs screenshots - easier to see the EGR Event - Open and Closed and what happens when EGR is commanded (open)

 

[afbryant]

I have been graphing a few drive cycles using FORscan and it seems that the EGR valve is opening. The other scanner evidently was not picking it up. Here are some of the data PIDs during one drive cycle. I had 16 PIDs going, but I am going to try to condense it down for space

EGR % demanded	EGR % actual	DPFE V	DPFE psi	MAP psi	MAP V	RPM	VSS MPH
0	0	1.5	-0.1	6.5	0.69	900	0
3.92	4	1.5	0	8.8	0.95	1300	5
8.24	8	1.54	0.1	13.9	1.48	1717	23
9.41	9	1.55	0.3	16.6	1.43	2105	31.7
10.59	10	1.55	0.5	13.6	1.41	2205	33.6
7.84	7	1.5	0.1	13.2	1.39	1514	51
1.57	2	1.49	0	8.6	0.92	1514	51
0	0	1.49	-0.1	6.7	0.73	1514	51

 

[afbryant]

I think this last STANDARD DPFE sensor did the trick but the scanner that I was using was not pick up the EGR opening? Correct me if I am wrong Airline. These numbers look about normal according to the info that you can see.. There are still no codes and still no surging

 

[airline tech]

I have been graphing a few drive cycles using FORscan and it seems that the EGR valve is opening. The other scanner evidently was not picking it up. Here are some of the data PIDs during one drive cycle. I had 16 PIDs going, but I am going to try to condense it down for space

EGR % demanded	EGR % actual	DPFE V	DPFE psi	MAP psi	MAP V	RPM	VSS MPH
0	0	1.5	-0.1	6.5	0.69	900	0
3.92	4	1.5	0	8.8	0.95	1300	5
8.24	8	1.54	0.1	13.9	1.48	1717	23
9.41	9	1.55	0.3	16.6	1.43	2105	31.7
10.59	10	1.55	0.5	13.6	1.41	2205	33.6
7.84	7	1.5	0.1	13.2	1.39	1514	51
1.57	2	1.49	0	8.6	0.92	1514	51
0	0	1.49	-0.1	6.7	0.73	1514	51

This is a - NORMAL - EGR Event and if you would have added the EGRT to the list, you would also have seen the EGRT - Temperature climb along with EGR Flow and when EGR Valve closed the temp would drop back down.

Since you (frame by frame) reviewed - you noted that the EGR Event is actually very quick (Only a few seconds) Open to Close.

Let's use this as an example of what happens - failed DPFE or under reporting DPFE

Failed DPFE Example Only

Using EGR Command & Actual - 10%
DPFE - would be under reporting (say still showing negative) or a lower Differential Pressure
Map - is still showing - 13.6 psi
PCM - expects the DPFE to be a (More Positive) reading than what it is reporting
PCM - Responds by - Commanding the EGR Valve to open farther
DPFE - Reports a slightly higher pressure - but still does not match (what the PCM wants to see)
PCM - Responds by - Commanding the EGR Valve to open farther
DPFE - Reports a pressure of some positive flow - PCM finally is happy and EGR event ends

So, as you can see and note - The MAP pressure will increase each time the EGR Valve opens farther - chocking the engine or (over diluting) it with EGR Gas for your current engine and vehicle speed.
The EGR flow is still there - it's just overloading the intake with un-needed EGR flow, so what should be 10% EGR - turns out to be 70% EGR.
This would be a visual on how the DPFE fails and also how moisture can plug the Ref port and skew the pressure readings.

 

[afbryant]

Uh oh, i WAS feeling good about all this data. I have 3 graphs of different drive cycles and the EGRT never changed from -40*F they are PIDS:
Exhaust gas recirculation Temperature Bank 1 Sensor 1 (EGRT11) and
EGR Exhaust gas recirculation Temperature Sensor C Bank 1 sensor 2 (EGRT_C)

Neither never left -40 *F through all the drive cycles looking at the graphs. I may have put in the wrong PIDs or I do have a problem. I will have to look again, I never noticed the temps even though I did have them graphed. I did notice that -40*F was a strange temp but neither fluctuated off 0

 

[airline tech]

Uh oh, i WAS feeling good about all this data. I have 3 graphs of different drive cycles and the EGRT never changed from -40*F they are PIDS:
Exhaust gas recirculation Temperature Bank 1 Sensor 1 (EGRT11) and
EGR Exhaust gas recirculation Temperature Sensor C Bank 1 sensor 2 (EGRT_C)

Neither never left -40 *F through all the drive cycles looking at the graphs. I may have put in the wrong PIDs or I do have a problem. I will have to look again, I never noticed the temps even though I did have them graphed. I did notice that -40*F was a strange temp but neither fluctuated off 0

The PID is Labeled - Exhaust Gas Recirculation Temperature - Sensor B - this is the EGRT mounted on the EGR Tube assembly - the other PIDs are not installed so they display a default value when viewing them on a scanner - one of those misleading things about scan tools - if you do not know the system - my scan tools display the same (-40) on a vehicle that had this specific PID tied to that sensor - then you would see a real value.

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