Hi guys,

i need help for this problem:

My beloved 2011 4.4 TDV8 a few months ago broke the high pressure pump (again). This time, instead of having the pump repaired, I had it replaced with a new one, I also had the injectors cleaned, as well as washing the entire system and replacing the diesel filter.

After months, finally the mechanic has reassembled everything, but .... the engine starts and runs well for a few moments, then it starts to work irregularly and (says the mechanic) the control unit goes into protection, has checked the parameters and tells me that the fuel pressure values are too high.

He tried replacing the pressure regulator on the (new) high pressure pump, but there was no improvement; he says that the injectors may need to be replaced (!!!).

Any suggestions?

I've no idea what the setup on the 4.4 TDV8 is so I'm only thinking aloud here.

Is there a fuel return back from the injectors to the tank? Could this be blocked causing the pressure to rise in the injector rail rather then allowing it to return as normal?

I'd be surprised if it needed 8 new injectors.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

The fuel cooler cools returned fuel. There is a valve in the lines just after the cooler that links to the inline fuel pump. The valve is part of that section of fuel line LR031822 which superseded an earlier version at vin BA352847. Perhaps that valve is faulty with increasing possibility if your vin is before BA352847.

I had all injectors out of my 2012 and tested by a Bosch diesel specialist, they were all pristine.

I think injectors is unlikely, because it would have to be a lot of them going wrong.
That said, you can have them out and tested a great deal cheaper than buying new ones if you want to eliminate that as a cause. One step further? get them re-furbished. The car runs beautifully afterwards...


.

I had them tested and refurbished just 5000 km ago, but then the H.P. pump broke again.

Mechanic said that the car starts well, fuel pressure reading at idle is 300 bar, but slowly rises to 600 bar and goes in LIMP.

Looking at the workshop manual the range should be between 300 and 900 bar at idle, therefore can't imagine why goes in LIMP.

That fuel pressure quoted in the manual will be across certain conditions such as idling, light load, full load, wide open throttle, etc.

600 bar of fuel pressure whilst idling might be outside of the parameters that the ECU is programmed to accept.

EDIT - Just read your post on the iMac rather then my phone and seen the bottom paragraph about the range you quoted being at idle so ignore me.

Definitely worth checking the return to the tank for all it'll take IMO. If that fails, I'd be looking for a more competent mechanic as something clearly isn't right in the way the car is chewing through injectors and high pressure fuel pumps.

I genuinely think you'd see 1 bad injector, not 8 so don't understand why he'd want you to replace all 8.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Is the HPFP meant to be timed? The pump on the 2.7 TDV6 isn't timed but it is on the 3.0 TDV6/SDV6 and the 4.4 is of the same generation as the 3.0 so might be. I don't have that section of the WSM but hopefully the mechanic doing the work does so probably not the cause.

See this current post which points to LTB01083, being a faulty electrical connection repair.
https://www.fullfatrr.com/forum/topic62087.html

Is this a common issue? lookslike the parts been superseded to LR112662 SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

LR112662 is listed only for the L405/L494 by various sites but that could easily be due to a failure to list also for the L322. Regardless, it does appear to be common enough to remember the issue to avoid expensive repairs that don't solve the problem.
Edit: The L322 uses the same pressure sensor and the same short link harness between the sensor and the engine loom so the repair kit must also apply to the L322. The short link harness has also been superseded.

Cool, the connector might be the issue then? SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

The TSB is to replace the connector on the engine harness but maybe both halves have been improved. Maybe cut them both off and replace with Deutsch connectors.

Finally solved.

Had the injectors removed and bench tested... strange to say but all 8 injectors had very high return pressure due to the fact that instead of nebulizing the fuel they just dripped (or previous overhaul performed under warranty was done very bad, or it was just stated). Replaced all 8 with a new set, now works properly.