eolys or lack of it

[renagade]

Hi Guy's
Well the car ( c5 2011 1.6 egs6 ) has done 81k now (still as good as ever now) but I keep waiting for the eolys light to come on to tell me I need some putting in the tank. What I would like to know is , where is the warning light and what does it look like ???

[milleplod]

I keep wondering when mine will come on too.....83k miles, no sign of it so far!

Pete

[Stickyfinger]

As the system is triggered by refilling the fuel tank (cap sensor) then if the car has been filled from Empty to top each time rather than frequent "top ups" then does this not reduce the total amount of Eolys injected and thus a reduction in the amount used ?

[milleplod]

From reading threads on here, I think that multiple refuellings (ie repeated £10 top-ups, rather than a tankful a month, for example) will make the system 'think' its used more eolys than it actually has - so the light comes on to say its low based on the number of times the fuel cap has been on and off, rather than it being any sort of actual measurement of the quantity used. Note that I said 'I think' though!

Pete

[GiveMeABreak]

Ok, so here is a how one of the Bosch system works on the X7 - there are other systems - Magneti Marelli / Siemens etc., that are similar, but here is the general principle for the additive element:
In order to inject an amount of additive proportional to the amount of fuel injected, an additive system has been developed.
The system is made up of the following components:

• A suction device with low level detection on the additive tank
• An additive injection system in the fuel tank

If the larger image does not display, click on the smaller one below to zoom it

• 1st case: So simply, if the new fuel level 'n2' is greater than the memorised fuel level 'n1' and the fuel filler cap has been opened and closed for longer than 5 seconds, a normal additive operation is completed.
• 2nd case: If the new fuel level 'n2' is greater than the memorised fuel level 'n1', but the fuel cap opening cycle has not been opened - then the faulty condition is applied (see the backup mode at the end).
• 3rd case: If the new fuel level 'n2' is equal to the memorised fuel level 'n1' and the fuel filler cap cycle has completed, then fuel additive equivalent to 0,5 litre of fuel is actioned.
• 4th case: If the new fuel level 'n2' is equal to the memorised fuel level 'n1' and the fuel filler cap cycle is faulty or has not completed a cycle, then no additive is injected - Normal operation.
• Engine stopped.
• Checking the additive level.

(*) Fuel filler cap cycle:
Opening of the fuel filler cap
Closing of the fuel filler cap

Note: The fuel filler cap cycle is effective if the time interval between opening and closing is greater than 5 seconds.

Checking the additive level: The engine management ECU continuously calculates the theoretical level of the additive reservoir(fuel quantity is counted from 0 to 168 g).
When the minimum additive reservoir level is reached by calculation, the engine management ECU authorises an additive adding margin corresponding to 5 additions of 80 litres of fuel, then it prohibits the injection of additive.

Total amount of additive injected
Each time additive is added, the engine management ECU memorises the quantity of additive injected.
This value is added to the previously injected values to give a value representing the total amount of additive injected since the beginning of the particle filter’s life.
This value is transmitted to the engine management ECU which uses it as the basis for management of the level of clogging of the particle filter by the cerine.

So here are the 'Backup Modes' for the Additive System in case of a fault:

3 main strategies are used if the additive systems develops faults.
Fuel filler cap faulty:
The engine management ECU uses the vehicle speed information in conjunction with the fuel gauge information to inject the additive.

Fuel sender fault:
The engine management ECU makes an addition equivalent to filling of the fuel tank; When the fuel filler cap is opened/closed.

Failure in communication on the multiplexed CAN network:
The engine management ECU makes an addition equivalent to filling of the fuel tank; When communications are interrupted for more than 10 seconds.

[Paul-R]

The image is not showing for me Marc. According to the properties it doesn't exist any more.

[GiveMeABreak]

Thanks Paul - I as experimenting to try and get a larger image for the table - you should see the smaller one now which you can zoom by clicking.

[Hell Razor5543]

I can now see it as well.

[Lenny]

When I had the fuel tank out of my C5 I saw nothing at all resembling a sensor by the fuel cap.
I expected a connector on the filler pipe as mentioned in the Citroen Service guide but mine had nothing - no electrical connections around the cap at all.

[Hell Razor5543]

Normally they use a simple magnet and reed switch affair. It is not unknown for the magnet to fall off, which means the ECUs do not 'see' when the cap is opened for fuel.

[Lenny]

Normally they use a simple magnet and reed switch affair. It is not unknown for the magnet to fall off, which means the ECUs do not 'see' when the cap is opened for fuel.

But there was no wiring or anything really.
The Citroen Service procedure said there'd be a plug up there to disconnect but there was nothing at all and everything I removed to get the tank out looked like it hadn't been disturbed since the car left the factory so I doubt anybody had been at it before me.
Was the fuel cap sensor thingy fitted to all C5 X7s or did they change the idea late in production?
(mine's a late 2010 160bhp)

[GiveMeABreak]

It may also depend on the type of injection variant fitted to your vehicle Lenny (Siemens, Delphi etc.). I can check if you can provide your VIN or Injection ECU type.

[Lenny]

It may also depend on the type of injection variant fitted to your vehicle Lenny (Siemens, Delphi etc.). I can check if you can provide your VIN or Injection ECU type.

Thanks Marc. I'll PM you the VIN.

[GiveMeABreak]

Ok Lenny, I've done some digging and you have the Delphi Injection ECU DCM 3.5. Now this system is different depending on the type of engine. In your case the DW10CTED4 engine.

So the additive system operates thus: (note there is no Fuel Cap Sensor used for this system on this Engine Type)

Fuel Additive Function - Engine ECU
The Engine ECU determines the amount of fuel put into the car from:

• The Fuel Gauge
• The Wheel Speed Sensors

Depending upon the quantity of fuel put in, the ECU takes the following actions:

• To determine the quantity of additive to be injected into the fuel tank.
• To control the fuel additive pump.

The engine ECU sends a request for additive to a total volume made up of one or more individual volumes each not exceeding 1265 mm3, to the fuel additive pump, via the BSI.
The engine ECU records in memory the weight of additive that is accumulated in the particle filter.
The engine ECU authorises or prohibits the applying of additive, as a function of the following parameters :

• State of the additive pump
• Level of additive remaining
• State of clogging of the particle filter
• Fuel gauge state

Note: The engine ECU sends an alert on the risk of clogging of the particle filter and on the level of additive being insufficient, as a function of the quantity of additive injected and of the weight of additive accumulated in the particle filter.

The additive pump sends to the engine ECU, via the BSI, the following information:

• Status of additive system (diagnosis of the additive system)
• Quantity of additive actually added

Role of the BSI:

• To memorise faults and to command alerts sent to the instrument panel
• To receive and transmit to the engine ECU information on the quantity of fuel put in
• To serve as a bridge between the engine ECU and the fuel additive pump

When the vehicle is stationary (wheel speed sensor information) and the ignition
switched off, the BSI memorises the level of fuel present in the tank.

When the ignition is switched on again and the vehicle starts moving, the BSI acquires and compares the level of fuel with the latest value memorised. If the new value is higher, the BSI transmits to the engine ECU the quantity of fuel that has been added.

The BSI receives the following information from the engine ECU:

• Minimum fuel additive level warning
• Risk of particle filter clogging

The BSI sends the following information from the engine ECU:

• State of the additive pump
• Fuel gauge state

Conditions for use of the fuel additive function
The engine controlled ECU controls the fuel additive pump when the following conditions met:

• Vehicle speed above 40 km/h or last fuel addition over 300 seconds
• Internal combustion engine running
• Starter switch in the ignition positive position
• Adequate additive level

[Lenny]

Marc that is absolutely brilliant.
Thanks very, very much for looking into this for me and putting my mind at rest about the 'missing' fuel cap sensor.