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1995-2002 Range Rover P38A
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Discussion Starter #1
Hi everyone,

New owner here, so bear with me for all of the newbie questions :)

When the engine is running idle, it revvs between 600-800 rpm. Will post a video showing it later on. When you come onto the throttle it runs perfectly smooth. The seller suggested that the fuel pump may have its marks from running 323k km, and a replacement of that would solve it. Does that sound reasonable? Other suggestions?
 

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1995-2002 Range Rover P38A
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Discussion Starter #3
Went to talk to a mechanic today. He thinks that it is one or more of the injectors that have become a bit sticky. First of, we try with some diesel additive, to see if that can make things run smoother. Otherwise I will have to look further into it.
 

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1995-2002 Range Rover P38A
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Hi Andreas
With that sort of mileage under its belt it could be a multitude of things, depending on what's been replaced and how well it was done!
Have a search on Diesel Idle Hunting and have a read through to see what others have encountered.
At a wild guess it could be worn pump or pump timing due to stretched timing chain, but that's a wild guess.
IIRC you bought a Faultmate. Have you done a diagnostics check on the engine?
 

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Discussion Starter #5
It has done 323000 kilometres :)

I just received the Faultmate today, it reports two faults on the engine ECU:
- Immobilizer link fault, too high - intermittent fault
- Boost pressure invalid value - major fault

As well as quite a bit of short circuit warnings on the Valeo HeVAC ECU.

I'll try and do a search on those, but if anyone in here has some experience with what to do about these fault, please let me know :)
 

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Discussion Starter #6
As far as I can see from other people experiences, a faulty boost pressure sensor can cause a wrong fuel blend ratio, causing the engine to hunt?
 

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1995-2002 Range Rover P38A
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Discussion Starter #7
Having a nice chat with myself here xD

The connector numbered C590 in RAVE looks like it has had en encounter with a mouse or something like it. The rubber cover has brokken, so I suspect that the connectors inside may have taken damage as well. Will start trying to place the connector to see if that solves my problem :)
 

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Install a mouse trap while you're in there :)
 

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Discussion Starter #9
Yeah, should do that xD

But where the *** do I get such a connector? Any suggestion to what I need to search for?
 

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1995-2002 Range Rover P38A
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If it's that knackered, probably someone breaking a P38 diesel would sell you the 3 pin boost pressure sensor connector with some cable left on. You can then solder it in and heat shrink
 

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1995-2002 Range Rover P38A
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Discussion Starter #11
Yeah that's what I thought. I will start searching through the local LR community :blush:
 

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I will start searching through the local LR community
Way outside my area of knowledge, but isn't it a BMW motor, so maybe broken BMW's as well?
 

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1995-2002 Range Rover P38A
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If the wiring is damaged to the Manifold Absolute Pressure, or MAP sensor, that could be your problem, particularly if Faultmate confirms there is a major fault due to boost pressure being an invalid value.
Repair the damage first, then clear the faults to see if they come back. If you do need to get another connector from a breaker, the engine wiring harness is a separate item from the main harness.

The MAP sensor on the p38 diesel is the standard BMW M51 engine part as used on the car engine. There is no boost at tick over. It only starts to kick in from 2500 rpm. Normal reading from Faultmate on tickover is around 100 kpa absolute (or atmospheric pressure) rising to 200 kpa at 3000 rpm onwards.

If there is still a problem, it is also worth checking the rubber tube that goes from the sensor to the inlet manifold. Check the pipe is clear and there are no splits. The sensor is bolted onto the fuel filter.

It could possibly be sticky injectors. As mentioned try injector cleaner in the fuel tank first. Takes a while as you need to use a full tank of fuel.
If there is still a problem, a diesel engineering shop could test them for you to see if the spray pattern is correct - be careful with No.4 injector. It has a sensor built in and is very expensive to replace.
Don't buy new; secondhand p38 injectors are dead cheap (except No.4 obviously). I bought a set off Ebay for spares. There is nothing much to them, just a simple mechanical pintle valve with a spring. I dismantled mine and soaked them in caustic soda to remove carbon buildup. They generally run OK though. The BMW car uses the same type of injectors but I am not sure about whether the nozzle size is the same.
 

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Discussion Starter #14
Thanks for the answers - this forum is absolutely great for new P38 owners! :D

I can see that a complete set of engine wiring harness is around £40, but since I only need the plug, I will try to find someone who is willing to sell me just that with some cable left on it. Unfortunately there are not many either P38's or BMW's of that age in DK.

Hope that will solve my problem, otherwise I will continue you troubleshooting :)
 

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Discussion Starter #15
BTW: Do you know what kinds of resistance I should be able to measure on the sensor, just to establish that the sensor is working correctly?
 

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Discussion Starter #16
Update: I have now been doing some tests. I could measure a 4.86 v supply to the sensor with the cable disconnected. However, when connected to the sensor it measures only 3.5 v, and no output og the signal pin. This leads me to believe that the sensor itself is faulty, or?
 

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I haven't had a problem with mine so have not looked that closely at it.
I think there are 3 pins? ...... - ve ground, + 5v reference voltage and the MAP signal output which varies from 0 to 5v for 100 to 200 kPa abs.
I am guessing but the signal I think should show 0v at atmospheric pressure. Can you take it off and bench test it?
Rig up a power supply and put some air pressure on the sensor?
 

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Discussion Starter #18
You are right - I will try that :)
 

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Discussion Starter #19
Okay so I soldered on a new plug, the fault message has disappeared, and the engine is running smoother and hunting less, but the problem hasn't completely been addressed.
 

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Maybe wait for the injector cleaner to do its work.
Have you checked the pipe from the MAP to the inlet manifold?
 
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