Quick question related to EGR valve

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Quick question related to EGR valve

Post by belaprops »

Good day to you all,

I have a few error codes and trying to investigate.
First Question if i may
GPR valve , is it open or close during idle.
Its seems it has been repaired on the actuator as shown in the pics but seems to move ok when i move it manualy.
The inlet to the manifold has a good suction on it when on idle..and other then oily residu not much in there.

Thanks in advange.
My car is a citroen c5 HDi 16 diesel, 11 plate
Attachments
20200510_121901.jpg
Last edited by GiveMeABreak on 10 May 2020, 22:22, edited 1 time in total.
Reason: Edited Title to show 'EGR'

User avatar
GiveMeABreak
Forum Admin Team
Posts: 19524
Joined: 15 Sep 2015, 19:38
x 1886

Re: Quick question related to GPR valve

Post by GiveMeABreak »

Sorry but I've no idea what a GPR valve is (and neither does Google it would seem). Do you mean EGR valve?

It will probably be best if you put your VIN up with the actual fault codes so we can be certain.

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to GPR valve

Post by belaprops »

Thanks Marc, you are right EGR.

Vin VF7**************[VIN obfuscated, can be read by forum staff]. I heard it can be determent from the VIN which type of engine it is but have not figured that out.

The last codes were P14A4 , P0487 , P2562
Im trying to find the turbo boost controle sensor related to the last code so i can check this but not found the location as yet.

When scanning for the codes i got a whole list and am not sure from when they are and how to clear them to start with a clean slate.

The other codes were P1497 , P1499 , A0A1A , U1401 , P0215 , P0215 , P107A , P129F

Its such a nice car but the engine is not right at the moment, so i hope i can find the problems and let it run smoothly again.

Cheers
Bela

User avatar
GiveMeABreak
Forum Admin Team
Posts: 19524
Joined: 15 Sep 2015, 19:38
x 1886

Re: Quick question related to EGR valve

Post by GiveMeABreak »

Ok, so you have a DW10CTED4 2.0 HDi 16 Valve Diesel.

So P14A4 is EGR exchanger by-pass: Confirmed locked shut (R.H. side). Closed position of the EGR exchanger by-pass switch not reached after 4 seconds even though the control is below 5 %

Fault will go after driving for 5 minutes from a cold engine, when the coolant temperature reaches 80°C.

Suspect areas:
  • EGR exchanger bypass: By-pass locked shut - Electrical harness
  • EGR exchanger bypass control solenoid valve: Failure of the solenoid valve - Electrical harness
  • EGR exchanger bypass position repeat: Electrical harness
  • Vacuum circuit
P0487: Air mixer: Position incorrect (Open too far). The position measured is greater than the reference by more than 50% for 6 seconds.

The Engine Management Light will come on and the engine stop will be downgraded whilst this fault is active.

Fault will go after driving with the engine hot for 5 min while remaining below an engine speed of 2500 rpm under half-load.

Suspect Areas: Air mixer, Electrical harnesses, Air doseur electrovalve, Air mixer position copy, Vacuum circuit

P2562: Variable geometry turbocharger: Position incorrect in relation to the requirement - Not enough turbocharging. The position measured is greater than the reference by more than 40 % for 6 seconds.

Fault will go after driving with the engine hot for 5 minutes. Whilst this fault is active, the EGR is deactivated and the Engine Management Light will come on. You may also notice Noise, Smoke from the exhaust, Lack of power, Loss of braking.

Suspect Areas:
  • Turbocharger: Variable geometry open
  • Turbocharger solenoid valve
  • Position indicator of the turbocharger
  • Electrical harness
  • Vacuum circuit

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to EGR valve

Post by belaprops »

Thanks Marc,

So the EGR valve not being closed on idle is because the engine is not hot yet.
But once it is on temp it should be shut on idle.

So i guess the vibrations of the engine i can feel quite a lot in the seat when idle is nothing to do with these errors.

My friend said it could be the injectors. Any other suggestion on reducing the vibrations or not smootly running or is this just 154k the engine has done.
I done a full tank of redex mixture but no results. The engine did 51 mpg on 2/3 motorway and a total of 750 miles on 67 litre, so it seems to be happy here.

User avatar
GiveMeABreak
Forum Admin Team
Posts: 19524
Joined: 15 Sep 2015, 19:38
x 1886

Re: Quick question related to EGR valve

Post by GiveMeABreak »

This is how the system works on this engine, which may be worth a read first, then see the last paragraph concerning operation parameters.

Role
To comply with the emission standards, the quantity of nitrous oxide (NOx) thrown out by the exhaust must be the lowest possible.
The exhaust gas recycling (EGR) device reduces the amount of nitrogen oxide (NOx) emitted by the exhaust.

Function
Exhaust gas recycling
  • The high temperatures, caused by the excess air combustion mode proper to diesel engines, produce a large amount of nitrous oxide (NOx).
  • The admission of exhaust gas into the combustion chamber reduces the quantity both of oxygen and of nitrogen present at combustion.
  • The temperature of combustion is then lessened, which reduces the amount of nitrous oxide (NOx) emitted.
  • Some of the exhaust gas is diverted into a duct linking the exhaust to the air intake.
  • This duct is closed by an electric EGR valve.
    On the command of the engine ECU, the electric EGR valve opens, giving the exhaust gases a controlled access to the inlet manifold.
Note: Too large a quantity of recycled exhaust gas causes an increase in emissions of soot, of carbon monoxide (CO) and of hydrocarbons (HC) by reason of poor combustion due to lack of air.
In addition to opening the electric EGR valve, the engine ECU orders the air mixer to close partially.

The closing of the air mixer causes:
  • A vacuum in the inlet manifold, drawing in the exhaust gases
  • A diminution of the amount of air entering
Cooling of the recycled exhaust gases
Cooling of the exhaust gases enables the emissions of nitrous oxide (NOx) to be further reduced.
The exhaust gases are able to be cooled, in order to prevent the total mix of air from reaching too high a temperature (Mixture of inlet air and recycled exhaust gas).
In certain operating phases, the exhaust gases do not have to be cooled before being admitted into the combustion chamber (Notably during cold starts, to allow the engine to warm up more rapidly).
The engine ECU, by means of a pneumatic electrovalve, operates a by-pass by which the exhaust gases go directly to the air inlet without passing through the EGR exchanger.

Initialisation of stops
To mitigate ageing and soiling of the EGR valve, an automatic initialisation of the high and low stops is performed when the EGR valve is at one of these limits for more than 0,5 seconds.
Taking account of the stop positions initialised automatically and comparing them with the original position initialised at the factory, the engine ECU adapts the setting for control of the EGR valve.
Initialisation of stops is not possible if the battery voltage is lower than 10 V or higher than 14 V.

Note: Initialisation can be performed using Diagbox.

Cleaning
To prevent soiling of the electric EGR valve, there is a cleaning phase on switching on the ignition.
This cleaning phase consists of one or more successive opening and closing cycles.
At the end of the cleaning cycle, the engine management ECU tries to reach the upper stop (maximum opening) of the electric EGR valve.
If during this attempt a blockage is detected, the cleaning cycle is repeated.
If, after this second attempt, the valve remains stuck, a fault appears.

Antisticking
The engine ECU estimates the state of sticking of the electric EGR valve, as a function of the following factors:
  • Speed of movement of the gate of the electric EGR valve
  • Errors in regulation of the position of the electric EGR valve
If the electric EGR valve is stuck or is beginning to stick, the engine ECU commands the electric EGR valve via a conventional control signal.
This signal is followed by a vibratory signal that makes the gate of the electric EGR valve vibrate in order to prevent the sticking.

Note: The amplitude of the vibratory signal depends on the degree of sticking detected by the engine ECU. The antisticking strategy is used only during phases where the electric EGR valve is being operated.

As for the operation of the EGR itself, see the following graph that will give you some indication of operation:
EGR Graph.PNG
"G" Zone of activation of the electric EGR valve.
"N" Engine speed.
"T" engine torque.

The electric EGR valve is deactivated in certain operating conditions:
  • Under conditions of engine speed and engine torque defined by the zone of activation "G"
  • At idle for a maximum time of 300 seconds
The exhaust gas is not cooled in the following conditions:
  • Engine torque below 140 N.m
  • Engine speed below 2500 rpm
  • Coolant temperature between 15°C and 60°C

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to EGR valve

Post by belaprops »

Again, thanks Marc,
What would your advice be where to find the schematic of the vacine.
I found that the problems might be the vacuum system as it not creating a vac on the lines. The pump is ok and sucks but somewhere there is something open.
Trying to figure out where they all go but as it is all behind the engine is hard to see.

Any suggestion
Regards
Bela

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to EGR valve

Post by belaprops »

Finally found the bad solenoid, i hope it is correct that the EGR solenoid either taking vacuum.to the actuator or not. At the moment it's going from the vac input straight to both outlets when it's on or off.

User avatar
GiveMeABreak
Forum Admin Team
Posts: 19524
Joined: 15 Sep 2015, 19:38
x 1886

Re: Quick question related to EGR valve

Post by GiveMeABreak »

Have a look at my post on this thread here - it gives you the layout of them on this engine:

viewtopic.php?p=643201#p643201

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to EGR valve

Post by belaprops »

Thanks Marc.
I'm wondering if a previous engineer has messed up the vac lines.
I'm trying to determine via the pictures how they run but is there a diagram of them.

To be sure , the final valve which I removed should be swichting between ports 100%, not as it is now were it's not fully closing on energizing.

I also found the voltage on the first solenoid was only about 8 volt, when idling.

Thanks again for your help

User avatar
GiveMeABreak
Forum Admin Team
Posts: 19524
Joined: 15 Sep 2015, 19:38
x 1886

Re: Quick question related to EGR valve

Post by GiveMeABreak »

Ok so here are the components of the vacuum circuit:
bela A.PNG
Bela B.PNG
Bela C.PNG
(1) vacuum pump.
"a" Vacuum reserve supply.
"b" Output to the brake servo unit.
(2) Air inlet manifold with integral vacuum reserve.
(3) Breather and filter for all the control electrovalves.
"c" Outlet towards the proportional electrovalves controlling the double mixer.
"d" Pressure drop inlet for the vacuum pump.
"e" Outlet to electrovalves:
Proportional electrovalve controlling the variable resistance turbocharger
Control electrovalve for the EGR heat exchanger by-pass
(4) Proportional electrovalve controlling the variable resistance turbocharger.
(5) Cold air circuit electrovalve.
(6) Hot air circuit electrovalve.
(7) Variable geometry turbocharger.

Here is the Air Supply Circuit:
Bela D.PNG
Key:
"A" Fresh air
"B" Cooled compressed air
"C" Hot compressed air
"D" Air inlet
"E" Exhaust gas
"F" Control vacuum
"G" Electrical links
ReferenceDesignation
"a"Turbocharger blades control diaphragm (With position copy sensor)
(1)Engine ECU
(2)Variable geometry turbocharger
(3)Proportional electrovalve controlling the variable resistance turbocharger
(4)Air flowmeter by mass
(5)Air filter unit
(6)Turbocharger air cooler
(7)Double air mixer with position repeat sensors
(8)Inlet air pressure and temperature sensor
(9)Turbo air cooler by-pass control electrovalve
(10)Air metering unit control electrovalve

belaprops
Posts: 41
Joined: 05 Dec 2019, 23:20

Re: Quick question related to EGR valve

Post by belaprops »

Thanks Marc,
With your help I be a Car mechanic soon, No work in technical Theatre now ! need to diversefy

What baffles me is when I close the vaccuum line where the 3rd (EGR ) solenoid was ( broken one ) with my manual vacuum pump/tester , and pump it , the actuator with which is operated by the 1st solenoid valve eventually retracts ( with 12v on the solenoid ) , engine off

But then when I start the engine and the vacuum is created by the pump, showing at least -30 on the dial , the actuator does not move a bit.
makes no sense to me , I must be missing something which is holding the actuator from moving.