High. Pressure sensor and Fuel Rail pressure plausibility P1190

Dreamed said:

By HP regulator you mean HP fuel sensor?

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No the HP pump has a pressure regulator which controls the HP rail pressure. If you look at the HP pump, you'll see a Junior connector on the end. This is the power to the regulator, which modulated by the EDC to control the rail pressure.

Ok I saw it, I'll check that when I have more space

Yup, no difference. It's coming from the pump. I think it's ok. I see no leak. I took the manifold out today and cleaned the MAP sensor....boy.... what a mucky business. I prepared everything for a new injector leak test....but if they don't leak I will be officially clueless.

I would need to test the pressure regulator somehow, without taking it out. Any ideas how? I was thinking to unplug the pressure regulator at tick-over. If it's working then I should get a pressure increase in the high fuel pressure?

How does the regulator work? Most traditional ones work with Vacuum air and a valve. But this one seems to be 100% electric controlling a valve.

Dreamed said:

I would need to test the pressure regulator somehow, without taking it out. Any ideas how?

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If the regulator is faulty or it's O rings are leaking, the engine won't start.

Dreamed said:

I was thinking to unplug the pressure regulator at tick-over. If it's working then I should get a pressure increase in the high fuel pressure?

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The rail pressure will collapse if the regulator isn't plugged in, so the engine will stop.

Dreamed said:

How does the regulator work? Most traditional ones work with Vacuum air and a valve. But this one seems to be 100% electric controlling a valve

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The regulator is just a solenoid bypass valve, very similar to the traditional run solenoid on an old technology diesel pump, but reversed in operation.
The solenoid valve is connected between the pump output and the return to the tank. So in order for the engine to run, the EDC modulates the solenoid valve, controlling the fuel flowing to the return line. This blocking of the return line in pluses, increases the fuel pressure in the HP fuel rail.
The EDC modulates the solenoid valve by varying the duty cycle, using feedback from the HP rail sensor to determine the fueling needed.


The fact the engine is running, proves the regulator is doing what it's supposed to be doing.

Nodge68 said:

If the regulator is faulty or it's O rings are leaking, the engine won't start.

The fact the engine is running, proves the regulator is doing what it's supposed to be doing.

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So basically, if I disconnect regulator's electrical connection( at tick-over for example) the engine will die, so I can't really test anything.

It takes around 6-8 cranks to start. But it starts. A tiny bit of blue smoke at start also.

What if the regulator's leak is not fully developed yet. What if the leak is not significant when there is no load. Can that be?

My injectors are fine. You say the regulator works too.

My LP provides enough fuel.

I changed crankcase filter and reinstalled EGR...

Hmm...I have no more options left.... almost.


Except MAF sensor..... could it be MAF at fault based on my symptoms? Is it possible to get a fuel rail code because of a bad MAF?


Thanks for all the info



PSI will upload a video with my live readings while doing a leak off test

From start to stop.

I have no clue what the hum sound at min 1:40 is.

I start reving later in the video.

Please help!

I've done a couple of tests yesterday. Driving around the city. Engine cut off 4 times. Unfortunately only captured on camera once. But captured several limps. I apologise for the video quality. It was the best I could do at the moment.

I also managed to trigger MIL stationary, just by pushing the throttle. This is new.

My assumptions:
1. Throttle sensor...throttle response. It seems that if I play with throttle up and down I can easily trigger MIL.

I noticed limps occur after an engine break (releasing throttle pedal suddenly). Sometimes, the engine break is smooth and gradual...sometimes it's very rough, makes my body move forward . When it's rough, if I press acceleration immediately after, most certainly engine limps.

2. Pressure regulator. I see pressure regulator current is very random. Sometimes I press the throttle and there is no reading. I have to do another test maybe: throttle + pressure regulator current.

3. MAF sensor. MAF readings are also very random sometimes. In the video, just before engine dies, MAF surges from 500 mg/stroke to 700, then engine dies. It's a big surge. Never saw it before. I'm waiting for my MAF torx to arrive. I will give it a clean. I will also drive with MAF disconnected.

In general MAF rarely goes 700+. Especially when I force the REVS..

I think readings should give a good indication of what is wrong....But I just don't know how to interpret yet....

They should all be avialable in HD. I've just uploaded them.

A better one. Should be in HD, after full processing.

Ok I guess, I'm left in the mud.... Just for the reference I just wanna restate something:

The only thing I can do to avoid getting limps and MIL... is to disconnect the high pressure sensor. The car works fine without it. I mean as good as it gets without the sensor.

I don't just want to replace it based on an assumption. The sensor gives readings after all....

Also I suspect pressure regulator as a possible culprit. If pressure regulator controls the high pressure sensor in any way, or vice versa then, any of the two can be broken . Yesterday for example, I saw something unusual. Just before engine cut off in traffic as I was accelerating, pressure regulator current went to 4V. Then car died. Very unusual high current. The load was not that big.... Most times under high load regulator goes up to 2.5V... Maybe it was an effort to increase pressure.... So that makes high pressure pump faulty....

But then... why is car not limping when common rail sensor is disconnected...

Dreamed said:

pressure regulator current went to 4V. Then car died. Very unusual high current. The load was not that big.... Most times under high load regulator goes up to 2.5V..

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That makes no sense. Current "C", and Voltage "V" are different things. So are you talking about regulator current or voltage?

Nodge68 said:

That makes no sense. Current "C", and Voltage "V" are different things. So are you talking about regulator current or voltage?

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You're right, I foolishly assumed the live readings of the pressure regulator current were showing the charge of the current, measured in Volts. But it seems they are actually showing how many Amps are flowing?

Either way, those readings were strange. 4+ Amps or Volts or whatever that reading measures were off the chart just before engine died.

The EDC opens the regulator by applying current. 4 Amps seems a lot, like the EDC is trying get the pressure as high as possible. It does point to a failure in the HP system somewhere, but I'm guessing it's not the regulator itself.

Here it is 30 seconds.

Nodge68 said:

The EDC opens the regulator by applying current. 4 Amps seems a lot, like the EDC is trying get the pressure as high as possible. It does point to a failure in the HP system somewhere, but I'm guessing it's not the regulator itself.

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It makes sense!

So now, looking back... I see the LP pump pressure drops to 100 just before engine stops. I don't know if that's a result of engine being cut off, or if LP causes all this chaos... As I said, LP seems a bit rusty and sounds funny. Dashboard lights, which indicate engine is dead, don't show up immediately after I lose power. They only show after 2-3 seconds as engine slows down. Which means...LP goes low...engine is still running cause of remaining HP fuel, but then dies as no more fuel is coming. I don't understand why there is no P1260 code then or LP code...

Dreamed said:

So now, looking back... I see the LP pump pressure drops to 100 just before engine stops. I don't know if that's a result of engine being cut off, or if LP causes all this chaos... As I said, LP seems a bit rusty and sounds funny.

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Sounds like a LP rail issue as the LP should remain above 250Kpa minimum, or the EDC shuts the engine down.

Nodge68 said:

Sounds like a LP rail issue as the LP should remain above 250Kpa minimum, or the EDC shuts the engine down.

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Well, that makes sense to me too... but the P1190 is so confusing.

Nodge68 said:

Sounds like a LP rail issue as the LP should remain above 250Kpa minimum, or the EDC shuts the engine down.

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Oh and another unexplained problem... if LP rail is the cause, and pressure does indeed drop under 250kpa, then why engine doesn't limp or dies with high pressure sensor disconnected...

Dreamed said:

Oh and another unexplained problem... if LP rail is the cause, and pressure does indeed drop under 250kpa, then why engine doesn't limp or dies with high pressure sensor disconnected...

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The EDC is designed to keep the engine running as best it can. So if a sensor fails, it will try to compensate the failed sensor by referencing other sensors if it can. However if it's getting more than one failed sensor, then it just runs fixed values for them. This is likely the reason it runs ok with the rail sensor disconnected. I don't know why it's not putting the MIL on though, as I think it should.

Nodge68 said:

The EDC is designed to keep the engine running as best it can. So if a sensor fails, it will try to compensate the failed sensor by referencing other sensors if it can. However if it's getting more than one failed sensor, then it just runs fixed values for them. This is likely the reason it runs ok with the rail sensor disconnected. I don't know why it's not putting the MIL on though, as I think it should.

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Assuming the filter is ok (replaced 3 weeks ago). What else can go wrong on the LP side except the pump? Maybe sender unit? Do you know how I can check the sender unit on these models? I know it's located under the back seats.

The low rail pressure sensor is located in the engine bay on the LH inner wing.

Mine did something similar to yours with the kangerooing/ missfires etc so went and bought the pressure sensor and wiring upgrade which I did and it cured the main issue ( starter was still gooosed though so got rid stupidly as could of been a good car!) anyway heres the tsb bulitin in my thread might be worth chcking the wires are in the correct place in the fuse box and correctly attached just to make sure its been wired up corrrdctly

https://www.landyzone.co.uk/land-rover/freelander-td4-fuel-rail-pressure-sensor-harness-tsb.307429/