Needle lift sensor invalid

Had a break down last night and had to be collected on the back of a truck. This is a diesel P38 from 1998. Going along nicely when after about half an hour she juddered, as with fuel starvation. That got worse and the engine fault light came on, didn't like to accelorate, and then the engine died. As we'd just left the petrol station thought it might be the cap. Had a spare on board so put that on. Bingo, she drove faultlessly the rest of the half-hour journey. Then on the way back after half an hour or so the same thing happened. This time if left a few moments it would spring back into life but then fail again. Put the nanocom on it and found 'Needle Lift Sensor invalid value. TYPE: High circuit, Invalid fault, Major Fault, Logged, Current.'

Where do I start? Any suggestions welcome.

BigJessie said:

Had a break down last night and had to be collected on the back of a truck. This is a diesel P38 from 1998. Going along nicely when after about half an hour she juddered, as with fuel starvation. That got worse and the engine fault light came on, didn't like to accelorate, and then the engine died. As we'd just left the petrol station thought it might be the cap. Had a spare on board so put that on. Bingo, she drove faultlessly the rest of the half-hour journey. Then on the way back after half an hour or so the same thing happened. This time if left a few moments it would spring back into life but then fail again. Put the nanocom on it and found 'Needle Lift Sensor invalid value. TYPE: High circuit, Invalid fault, Major Fault, Logged, Current.'

Where do I start? Any suggestions welcome.

Click to expand...

Needle lift sensor measures start of injection to send message to ECU. Could be faulty sensor injector, if so may need need changing. Believe there are 2 types pre EGR and one for EGR models. Pricey though.
Better help will follow

Notwithstanding the fault code if all you did was remove & fit another fuel tank cap I wonder if you have no tank breathing & as fuel is used it creates a vacuum - which will eventually stop fuel delivery.
Would fit with removing the filler cap to fit the replacement as this would allow air into the tank & you said it ran faultlessly after you did that.

BigJessie said:

Had a break down last night and had to be collected on the back of a truck. This is a diesel P38 from 1998. Going along nicely when after about half an hour she juddered, as with fuel starvation. That got worse and the engine fault light came on, didn't like to accelorate, and then the engine died. As we'd just left the petrol station thought it might be the cap. Had a spare on board so put that on. Bingo, she drove faultlessly the rest of the half-hour journey. Then on the way back after half an hour or so the same thing happened. This time if left a few moments it would spring back into life but then fail again. Put the nanocom on it and found 'Needle Lift Sensor invalid value. TYPE: High circuit, Invalid fault, Major Fault, Logged, Current.'

Where do I start? Any suggestions welcome.

Click to expand...

If you clear the faults, do they come back? Check the connector for the needle lift sensor.

Yes, I cleared the faults three times and each time the same fault came back.

Also I unscrewed the replacement filler cap. I wonder whether the filler cap business was just a coincidence. From what I understand, the lack of power will be caused by some problem, and then the computer operates the kill solenoid to stop the engine, so as to make sure no damage is incurred. This I found slightly alarming on the M6.

This morning thought I'd take a quick look. Nothing obvious under the bonnet but a smell of unburnt fuel. I went into OURPUTS on Nanocom and found Timing modulation figure at idle of 93. I see from other threads that this is too high.

BigJessie said:

This morning thought I'd take a quick look. Nothing obvious under the bonnet but a smell of unburnt fuel. I went into OURPUTS on Nanocom and found Timing modulation figure at idle of 93. I see from other threads that this is too high.

Click to expand...

It is high on a cold engine. You need about 50% on a hot engine circa 95 deg iirc.

Okay, shall warm it up and see what happens.

BigJessie said:

Okay, shall warm it up and see what happens.

Click to expand...

With the engine temperature at 95C on Nanocom, the modulation should be 50%. I can give you an easy way of doing the modulation without a DTI and it produces a more accurate result. PM me with an Email address if you want the info.

BigJessie said:

This morning thought I'd take a quick look. Nothing obvious under the bonnet but a smell of unburnt fuel. I went into OURPUTS on Nanocom and found Timing modulation figure at idle of 93. I see from other threads that this is too high.

Click to expand...

Did my modulation using datatec's method last week. With Nanocom its a doddle. Got mine down from 84% to 52%.

BigJessie said:

Had a break down last night and had to be collected on the back of a truck. This is a diesel P38 from 1998. Going along nicely when after about half an hour she juddered, as with fuel starvation. That got worse and the engine fault light came on, didn't like to accelorate, and then the engine died. As we'd just left the petrol station thought it might be the cap. Had a spare on board so put that on. Bingo, she drove faultlessly the rest of the half-hour journey. Then on the way back after half an hour or so the same thing happened. This time if left a few moments it would spring back into life but then fail again. Put the nanocom on it and found 'Needle Lift Sensor invalid value. TYPE: High circuit, Invalid fault, Major Fault, Logged, Current.'

Where do I start? Any suggestions welcome.

Click to expand...

Needle lift sensor is inside injector #4. It needs the wiring to be intact but it also needs fuel to move the needle in the injector. So, could be fuel startvation or damaged wire in the injector. I cannot recall if it runs on default values with the #4 plug unplugged (plugs in just beneath the injector behind the high pressure pipes and with one of those metal clips you push in to release it) but it might say in RAVE.

Thanks for your help so far. I am still trying to get my head around the fault, and also the way the system works. I took her for a short run to warm up the engine. After five minutes the engine fault light began to flicker if I went over around 1200-1500 revs. Got home and plugged in the Nanocom. The only fault recorded was in a Glow plug:
Glow plug (heating) fault
RPM= 0
Water temp = 207
Occ = 11
I know that I need to change the glow plugs and have already bought a set.

Water temp = 90 degrees
Fuel temp = 33.88
SWG set point (mv) = 3225.60
SWG actual (mv) = 2760
Inj. ser point degrees = 1.85
Inj actual degrees = 1.95
Timing modulation = 69.80

I checked the wiring of the needle lift sensor and it seemed fine. Perhaps I should change it.
Thanks - and I shall have to work out how to write a PM!

Click on the user name of who you want to pm, then click on 'start a conversation '.

Or click on the envelope symbol next to your user name above search box

BigJessie said:

Thanks for your help so far. I am still trying to get my head around the fault, and also the way the system works. I took her for a short run to warm up the engine. After five minutes the engine fault light began to flicker if I went over around 1200-1500 revs. Got home and plugged in the Nanocom. The only fault recorded was in a Glow plug:
Glow plug (heating) fault
RPM= 0
Water temp = 207
Occ = 11
I know that I need to change the glow plugs and have already bought a set.

Water temp = 90 degrees
Fuel temp = 33.88
SWG set point (mv) = 3225.60
SWG actual (mv) = 2760
Inj. ser point degrees = 1.85
Inj actual degrees = 1.95
Timing modulation = 69.80

I checked the wiring of the needle lift sensor and it seemed fine. Perhaps I should change it.
Thanks - and I shall have to work out how to write a PM!

Click to expand...

Put a meter across the pins of the needle lift sensor connector and see what resistance reading you get.

BigJessie said:

Thanks for your help so far. I am still trying to get my head around the fault, and also the way the system works. I took her for a short run to warm up the engine. After five minutes the engine fault light began to flicker if I went over around 1200-1500 revs. Got home and plugged in the Nanocom. The only fault recorded was in a Glow plug:
Glow plug (heating) fault
RPM= 0
Water temp = 207
Occ = 11
I know that I need to change the glow plugs and have already bought a set.

Water temp = 90 degrees
Fuel temp = 33.88
SWG set point (mv) = 3225.60
SWG actual (mv) = 2760
Inj. ser point degrees = 1.85
Inj actual degrees = 1.95
Timing modulation = 69.80

I checked the wiring of the needle lift sensor and it seemed fine. Perhaps I should change it.
Thanks - and I shall have to work out how to write a PM!

Click to expand...

The injector actual degrees is from the lift sensor so it must be working now.

Thanks for that. I did try to unplug the connector from the lift sensor in order to check resistance but my hands just can't fit under the mainfold and around the pipes. If we assume the sensor is working correctly perhaps I should go back to look at modulation.

Well, after nearly a year I have finally found the willpower to sort out the old girl (this was the fourth time she has had to be recovered in eight years of ownership). I renewed the glow plugs - all but Number 4 which seems impossible to get a socket on because of adjacent plastic housing. One of the glow plugs was loose, and the gasket for another had blown through. Perhaps these affected the electric brain. Anyway, I put a meter across the lift sensor and read 115 ohms. From checking elsewhere I think this is the correct reading for a working sensor.

I am hoping that the leaking inlet gasket and/or loose glow plug were allowing air through and fooling the electric brain.

I assume the plastic housing is the inlet manifold as fitted to later models? I usually take that off as it only takes 5 minutes and access is so much easier.