C5 ll Fuel problem

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Ceenine
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C5 ll Fuel problem

Post by Ceenine »

I have a 2007 2.2 litre HDI, the last of the old shape before the X7. I have a peculiar fuel problem in that if I drive for several kilometres (say 4 miles) and I come to a halt, the engine cuts out.

When I do a Lexia diagnostic, the injection section shows a PO 104 (flow meter permanent open circuit) if the engine is not running, and no fault if engine is running (after clearing faults). From reading posts on this forum, there are many faults that can bring up this message. The PO 104 fault displays turbo pressure voltage of 627 mv. However engine is not running when the fault is displayed so this measure probably means very little.

The car starts with no hesitation and restarts in the same manner after it cuts out when idling.

Any thoughts please?

Don
Peter.N.
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Re: C5 ll Fuel problem

Post by Peter.N. »

My first thought would be the fuel filter, if that's been changed recently the pressure regulator on the back of the HP diesel pump can give all manner of problems if the internal filter gets blocked. It relatively easy to change.

Peter

https://www.ebay.co.uk/itm/BOSCH-Fuel-P ... SwZy1drIXc
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GiveMeABreak
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Re: C5 ll Fuel problem

Post by GiveMeABreak »

Don

Can you post the VIN of this C5, as there are 2 variants of 2.2 engine and the codes may have slightly different meanings for each.

However, from what I can see P0104 is specifically triggered by the Air Flow Meter (MAF). Something isn't working right - so that the frequency reading being sent to the engine ECU is incorrect and is causing the problem. It could be either the MAF itself, a leak in the air hose going to the MAF so that the readings are incorrect, an electrical connection to the MAF etc.

Until I have VIN confirmation, I'm going on the 2.2 175 engine here - so will have to confirm this still applies once you have provided the info.

The MAF (41) in the 2.2 175 engine has 2 sensors - the inlet mass air flow sensor (43) and the inlet air temperature sensor (42).
MAF.PNG

Air Flow Frequency:
This varies in relation to the Air Flow - lower frequency for more air entering:

Frequency = 11000 Hz: Engine stopped, ignition on (No air flow)
Frequency = 5500 Hz: Engine idling (Medium air flow)
Frequency = 1000 Hz: Engine full load (Maximum air flow)

How this affects the Engine ECU:
  • The calculation of the rate of recirculation of the exhaust gas
  • The calculation of the turbocharging pressure
  • The flow to be injected to limit fumes
The Sensor for the Inlet Air Temperature Sensor in the MAF has the following impact on the Engine ECU:
From this information the diesel injection ECU determines the following parameters :
  • The calculation of the theoretical volume of air
  • The calculation of the injection advance
  • The calculation of the injection flow
  • The activation of the additional heating (on the order of the BSI)
Inlet air temperature (°C)Nominal resistance(ohm)Output voltage( volts)
2024002,7
4011001,8
So you can see from the above how it can affect the Turbo Pressure - so I would keep focused on the MAF before swapping other parts to be honest as this is specifically what the fault is pointing too. When you clear the fault codes, that won't do anything - the fault will appear again as soon as the conditions are right to trigger it and this will depend on the amount of air flow entering the engine - hence why it may be stalling when idling or coming to a standstill.

I would get some MAF cleaner first (don't touch or brush the contact wire with anything except the spray or you will knacker it). See if that solves the issue - then check the hose for leaks / splits / cracks and then the electrical connection.
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Re: C5 ll Fuel problem

Post by Ceenine »

Marc,
I have changed over a known correctly functioning MAF sensor from another vehicle. The error code PO 104 remains. I have cleaned my own Siemens VDO sensor. Same result,

I have replaced the fuel filter with a new one.

I have taken out the primer bulb and replaced with a piece of fuel hose. Prior to doing so I noticed air in the clear section between the fuel filter and the primer bulb.

I don’t have thre vin to hand as I am typing this in bed but it is the last engine of of the old shape .being 12BTED4.

Could air be entering at the junction of the fuel line from the clear section from the primer to the air filter .

Don
Ceenine
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Re: C5 ll Fuel problem

Post by Ceenine »

Peter
Where is the fuel pressure regulator? The fuel filter has never been blocked. However I guess the regulator could play up without a blockage. I will attempt to change from a donor vehicle.

The question remains as to why the regulator would behave until the engine warms up.
Don
Peter.N.
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Re: C5 ll Fuel problem

Post by Peter.N. »

The regulator is on the back of the HP diesel pump behind the oil filter, you will probably have to remove the fuel filter to get at it, it is secured by two allen or philips screws, then just pulls off after you have disconnected the plug.

I had problems with mine on a Mk1 C5 with the 2.0. engine but I believe yours uses the same one. I had several problems but the most memorable one was that it wouldn't start when it got hot, I replaced it with a second hand one for very little money and it cured all the problems.

I can't guarantee that it will fix yours but that what I found mine to be.

Peter
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Re: C5 ll Fuel problem

Post by lexi »

Yours was the old Bosch system Peter, pump in tank. This is a different animal.
Peter.N.
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Re: C5 ll Fuel problem

Post by Peter.N. »

Ah right. that regulator was listed for a 2007 C5 but perhaps its a different engine.

Peter
Ceenine
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Re: C5 ll Fuel problem

Post by Ceenine »

Marc
My VIN is VF7**************[VIN obfuscated, can be read by forum staff].

I have discovered that I am getting bubbles in the fuel line immediately before and immediately after the fuel filter. By blowing down the fuel line from the motor side, I find that there is adequate resistance. The same result by blowing down the fuel line from the other side of the fuel filter. This leads me to the conclusion that air is coming from down the fuel line towards the fuel tank. What do readers believe is the most likely source of the air? That is, what is the likely weak point in the line?
Don
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GiveMeABreak
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Re: C5 ll Fuel problem

Post by GiveMeABreak »

Ok, so I have the correct engine - so what I posted before is relevant after checking your VIN.

The obvious thing to me is a) did you change the fuel filter? and b) if so, did you bleed the circuit? This is not simply a matter of using the priming bulb - is has to have the 'T' union connected up first is seems. The dealer would have the appropriate 'T' shaped connection pipes to do this.

Click Images to Zoom

Here is the full procedure for this engine (DW12BTED4) 2.2 175.

Removing & Refitting the Fuel Filter

Tooling
Ceenine Tool A.PNG
Ceenine Tool B.PNG
Plug KitSODIMAC Cleaning Product
Ceenine Tool C.PNG
Ceenine Tool D.PNG
Union Blanking CoversFilter Draining Connector
Disconnect Battery! Procedure (BSI Reset / Battery Disconnect / Reconnect Procedure)

Remove:
  • The protective panel under the engine
  • The engine cover
Protect the Alternator
Ceenine A.PNG
Ceenine B.PNG
Place a draining tray under the engine.
Open the bleed screw ( 5).
Clean the filter unions of the pipes (1 - 2 - 3 - 4)
using the tools [2], a brush & tray.

Unplug:
  • The connector "a"
  • The connector "b"
Unclip the electrical harness (at " c").
Uncouple the pipes (1 - 2 - 3 - 4).

CAUTION: Plug the fuel pipes and the pipes
on the fuel filter using the tools [1], [5].


Remove the fuel filter protection shield (7).
Close the bleed screw (5).
Remove:
  • The 3 fuel filter (8) fixing bolts
  • The fuel filter (6)

Refitting
CAUTION: Only open the sachet containing the new fuel filter just before fitting.

Refit:
  • The fuel filter (6)
  • The 3 fuel filter (8) fixing bolts
  • The fuel filter (7) protective screen
Reclip the electrical harness (at " c").
Couple the pipes (1 - 3).

Reconnect:
  • The connector "a"
  • The connector "b"
Bleeding the Supply Circuit
Ceenine C.PNG
CAUTION: The fuel filter is fitted with a degassing function.

Connect the female union (Ø 10 mm at "e") of the tool [6] in place of the pipe (4).
Insert the unions (Ø 8 mm at "d" and "f") of the tool [6] in place of the pipe (2).

Note: Refer to Previous Diagrams for Pipe Number references

Operate the priming pump ( 9) for 1 minute.
Allow the fuel filter to degas for 1 minute.

Remove:
  • The tool [6]
  • The tool [ 5] from the pipes (2 - 4)
Couple the pipes ( 2 - 4).
Remove the alternator protector.
Checking the Seal
CAUTION: After actioning 10 times on the priming pump (9), the engine should start within 15 to 20 seconds.

Reconnect the battery. (refer to reconnection part of the previous Procedure linked to above)

Operate the priming pump (9) several times (10 times).
Start the engine.
Check the absence of leaks.

Refit:
  • The style cover
  • The protective panel under the engine (see the relevant operation)
Bleed During Standard Servicing (Presence of Water)
This operation applies only during routine servicing, but is included here for completeness:
Ceenine D.PNG
Place a draining tray under the engine.
Open the bleed screw ( 5).
Operate the priming pump ( 9) several times.
Close the bleed screw ( 5).
Ceenine
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Re: C5 ll Fuel problem

Post by Ceenine »

Thanks Marc,
I will degas as much as possible and see how the car performs. However I think I had this problem before I replaced the air filter.
I will report back for assistance to others who have the same problem.
Don
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GiveMeABreak
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Re: C5 ll Fuel problem

Post by GiveMeABreak »

Please do Don.

Sounds like that could be The Crystals for a second :roll:

♪ da do Don Don♫, ♪da do Don Don ♫
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Paul-R
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Re: C5 ll Fuel problem

Post by Paul-R »

GiveMeABreak wrote:
10 Jan 2020, 22:23
♪ da do Don Don♫, ♪da do Don Don ♫
Ceenine
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Re: C5 ll Fuel problem

Post by Ceenine »

Marc
I suggest you stick with your day job and leave a vocation in comedy/musicals a very wide berth.
Don
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Re: C5 ll Fuel problem

Post by GiveMeABreak »

I know - it was a long day and probably 50 +posts!