HDI cut out problems (moved from wanted forum)

[howiedean]

Thats ok to test if you have appropriate equipment and details to test them, but when you haven't...

Good post DickieG, interesting to keep in mind next time I have an HDi playing up.

paul

PS: Incidentally, what methods of test did you do??

As follows;

I had a diagnostic check done today and it returned a 1112 code + (glow plug curcuit code also, poor starting problem?) which supports the above.

According to the Citroën diagnostic manual for Xantia HDi's, fault code 1112 is a major fault which should illuminate the diagnostic warning light, has that occurred? The fault relates to fuel high pressure monitoring.

The list of items to check in relation to that fault are as follows;

-Fuel pressure too high (greater than 1450 bars) check the fuel pressure sensor and the fuel pressure regulator (seizure risk)

-Fuel pressure too low;
Lack of fuel
Clogging of the fuel filter
Check the fuel high pressure pump and the diesel injector return flow ( a diesel injector in good condition has a slow dripping return flow)

-Fuel pressure regulator control too large (Open Cycle Ratio >93%)
The fuel pressure regulator is unable to maintain the fuel pressure;
List of possible faults as above.

-Fuel pressure regulator seized; replace.
-Lack of pressure;search for any possible internal or external leaks.
-Fuel pressure too high; check the fuel pressure sensor and the fuel pressure regulator (seizure risk).

To test the fuel high pressure sensor with the ignition switched on (ECU connected) check the supply voltage between contacts 1 and 3 in the supply connector which should be between 4.8 - 5.15 Volts.
To test the fuel pressure signal voltage;
Connect a voltmeter between contacts 1 and 2 on the same connector ignition switched on;
Engine stopped 0.5 V
Fuel pressure sensor disconnected 5 V
With the engine running the signal pressure should vary between 0.3 V and 4.7 V.

To test the fuel pressure regulator on the high pressure pump;
Connect an ohmmeter between the two pins on the regulator where you should get a resistance of 2,3 ohms.
Check the continuity between terminal 50 of the engine ECU and terminal 1 of the relay 1304.
After the ignition has been switched off, the injection ECU controls the opening of the fuel pressure regulator. The engine should drop from 500rpm within 1.5 seconds. Otherwise the fuel pressure regulator is considered as being faulty (this was happening to the Picasso I mentioned above).

Thanks for the above,
I appreciate the information above and will have a look, the diagnostic warning light illuminates then goes out after the engine has been running for a while. The engine will only cut out if the car is accelerating hard above 2500 rpm, to get it to start again it can take a few seconds.
I decided to change the tank pump as it was starting to fail, that is occasionally no output at the fuel filter. I then suspected the ignition relay for the engine cut out however it looks like I may have two faults as the diagnostic reader displayed a Glow plug circuit error (the temp was near freezing and the car took a couple more seconds to fire up).

Reference the items I have changed / looked at:
Fuel filter
Filter housing (from scrappy £5)
Fuel pressure sensor (from scrappy £14)
In Tank Pump (confirmed failure and it had done 100000 miles)
ECU removed and reseated
Various plugs disconnected / reconnected
HP Fuel pump and regulator (not yet arrived £60)

My view was that the cost of the various scrappy items that I've replaced have been a fair bit cheaper than getting a lexia check done. Generally unless you have spare sensors for diagnostic swaps then a mechanic will suggest replacing expensive items until they find the right one anyway.

The other problem that I have found is that with the car stationary it will not cut out regardless of how many revs you give it, therefore it needs to be on full boost which is when the car is demanding full fuel pressure.

Thanks for your replies, I will keep you informed as I progress through some of DickieG 's checks!!

Regards

Howie

[DickieG]

As the car has suffered a low pressure pump failure there may well be some swarf left on the pressure regulator pin as I described above, in addition has the fuel filter and its housing been replaced with new ones since the pump failure as when the pump fails parts of the pump apparently disintegrate and move along the fuel lines. Citroën recommend replacing the filter housing as "good practice" whenever the low pressure pump fails.

[howiedean]

As the car has suffered a low pressure pump failure there may well be some swarf left on the pressure regulator pin as I described above, in addition has the fuel filter and its housing been replaced with new ones since the pump failure as when the pump fails parts of the pump apparently disintegrate and move along the fuel lines. Citroën recommend replacing the filter housing as "good practice" whenever the low pressure pump fails.

I've read that before regarding the filter housing, although I've been using an inline filter after the main filter housing after reading issues with crap getting past. I will have a look for swarf ASAP.

DickieG, do my previous findings make sense to you?

Howie

[DickieG]

DickieG, do my previous findings make sense to you?

Yes I can see where you're going with this but my advice is to keep it simple and check everything before replacing parts with 'unknown' second hand items as you may introduce additional faults if those parts are beyond their best.

The other problem that I have found is that with the car stationary it will not cut out regardless of how many revs you give it, therefore it needs to be on full boost which is when the car is demanding full fuel pressure

Possibly because the fuel pressure system is below specification, explained by the pressure regulator being able to supply sufficient fuel to allow the engine to rev to 4,000 rpm because the load is so light, I'll have to check on this but I think the fuel pressure will be the same at any given engine speed, its the duration of the injector opening time that varies as the load is increased.

Having observed the datastream of fuel pressure on a HDi engine as its revved, the fuel pressure increases quite dramatically in relation to higher engine speeds.

Whereabouts are you? Are you near to one of us Lexia owners?

[RichardW]

I'll have to check on this but I think the fuel pressure will be the same at any given engine speed, its the duration of the injector opening time that varies as the load is increased.

Believe that's correct - rail pressure at idle is 297 bar, rising to 1650 bar or something stupid at max revs. Later generation CRs are pushing 2000 bar at full revs

[steelcityuk]

Hi Howie,

Have you tried a leak back test of the injectors? My thoughts being that if the lift pump failed it could have shed particles into the fuel system that's damaged the injectors and/or injector pump. At lower load the leak back may not be a problem but as the load and pressure increases the leak back becomes a significant percentage of the fuel needed.

I believe Renault sell a cheap kit for measuring this.

Maybe this is the reason dealers like to change all the fuel system components if swarf is found in the filter housing - if you're not careful you could damage new parts by existing contamination.

As far as I know the HDi does use it's glowplugs after the engine is started to improve emissions and smooth the idle. I've not checked this but it would be easy with a multimeter or a lightbulb.

Steve.

[howiedean]

Sorry for the delay in getting back. I replaced the fuel pump regulator and the problem was much better, however the car was still cutting out when the fuel was low.

I noticed hardly any fuel pumping out from the fuel filter in thefault condition. I replaced the fuel filter previously and it exhibited the same symptoms therefore I think this was not the issue. I bypassed the fuel filter system with a simple in line filter and cured my fault.

For now I have purchased a diesel fuel filter from a Rover 45 Diesel and bypassed the Citroen filter housing completely.

One thing I'm not sure about is what is the reason for the fuel return feeding back into the fuel filter? My guess was that it is aid the fuel heating prior to fuel entering the HP pump (constant fuel looping through the filter and HP pump, rather than back to the fuel tank)?
Anyway I've blanked off the fuel return to the fuel filter and connected the new fuel pump effectively in line, the only issue now is that I've got no fuel heater in my system. If this system works I will keep it as it is cheap to replace and no worry of crap getting past the nasty Citroen filter.

Regards

Howie

[citroenxm]

I wonder if the HDi engines suffer the same problem as ALL previous XUD engines (Except the 1.9 engines with the filter ON THE thermostat house) in that engines with a canister filter seperate to the engine, have engine mounted fuel heaters in which a house is mounted to the engine and heats the fuel.. the XM 2.1 unit has them, and the BX 1.8 Turbo units had them, and these are known for failure...

The HDi also has this feature, in that the fuel DOES pass through the thermostat house on the gearbox end of the engine, would there be a problem there like early engines?? I wonder..

Paul

[howiedean]

For anyone who is interested I've attached a photo of my fuel filter replacement. Once I'm happy with the results I'll tidy the fuel pipework a bit and disconnect the heating pipes from the original filter housing.




And with an old inner tube wrapped around filter to stop chaffing.





Regards

Howie