Member Since: 06 Mar 2017
Location: Lost
Posts: 5036
I have copied the live values below from one of my posts last year for a similar issue which turned out to be the alternator at fault.
In the "eng live values" (full list) on the IID you can see below the throttle potientiometers with the engine at idle. However, you can also monitor the voltages climb as you depress the throttle pedal. You should see a steady uninterrupted increase in voltage whilst the two values slowly rise and eventually read their maximum of 4.00v and 2.00v respectively. (full hard depressed throttle)
This may be of no help to you, but if there are interruptions I would find the throttle pedal suspect despite no dtc's to support. Its perhaps worth a punt!! You do not need to have the engine running to run the test, the live values below were taken from an 08 D3 (EU4) running perfectly.
If there is no progress and you are certain the wiring/earths are all good a second hand alternator might be worth trying!!
(from earlier post)
"When you get it started the following should give you an idea of what things should look like with the engine running at idle. Note, this was taken from a fully warmed up D3 2008MY. I did not include everything such as egr data etc as it is irrelevant in this case."
Voltage ign key on 13.84v
Voltage from DC converter 48.62v
Volume control valve 21.87%
Throttle pedal angle 0%
Pedal sensor 1 voltage 0.75v
Pedal sensor 2 voltage 0.25v
Pressure cntrl valve 13.67%
Mass air flow sensor signal A 4 g/s
Intake air temp 24deg C
Internal ECU temp 35 degC
Input/output status fuel lift pump. ACTIVE
Input/output status fuel lift pump power monitor. ACTIVE
Boost pressure actuator Bank 1. 0.87%
Boost pressure adjustment 87%
Fuel rail temp before FMEM 60degC
Generator command 46.87%
Generator feedback 23.84%
Generator voltage set point 15.70v
Fuel pressure 23.09 MPa
Engine speed 516 rpm
Eng oil temp 77degC
Coolant temp 78degC
Cylinder balance offset:
Injector 1. 103k. Inj 2. 0.99k. Inj 3. 0.84k. Inj 4. 0.93k. Inj 5. 0.98k. Inj 6. 1.19k
Ambient temp 12 degC
Battery voltage 13.97v
Boost air temp 22.30degC
These live screen shots taken today 20/11/19, which is why the base line is slightly different from that above.
Closed throttle
Full open throttle
yµ (idµ - eAµ) ψ=mψ
20th Nov 2019 4:31 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Thanx, I have read the complete post from Last year.
The accelerator Pedal I have checked with a scope on both potentiometers. I found two clean curves. One double and the other half the voltage. The Pedal should be OK. The Idea with the alternator ist very good. As the Disco has a generator controlled by the car's ECU. This control depends on temperature and engine load. And these Controllers often also work with the internal 5V voltage. I will report next week.
Lucky to have a second car and bike.
22nd Nov 2019 1:17 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5036
Yes it does seem like an alternator or earth issue as suggested in another thread. You could try a "known to be good" used alternator, but if you are replacing new it must be a Denso alternator and nothing else ! yµ (idµ - eAµ) ψ=mψ
22nd Nov 2019 2:44 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
It's solved. Disco is on the Road again!!! :
After changing the alternator the issue was still present. So I took the wiring diagram again and some literature about engine management and listed all sensors and circuits which are connected to the 5V reference circuit A(or 1). These are not so many. The EGRs, the MAP sensor, accelerator pedal, DPF differential pressure sensor and maybe the turbo actuator vane (from VIN 493487) . First I replaced the MAP sensor and checked the wiring by eye and ohmmeter. I found all OK and problem still present. After this I renewed the differential pressure sensor under the car. Wiring check by eye is not possible here because the 3 wires to the sensor are integrated to the gearbox and transfercase loom above the gearbox.
So I took my IID tool and checked live graphs of differential pressure and internal 5V circuit 1 from ECU.
Driven the car 3 miles till it got warm and the first voltage dips appeared. Now I could see nearly everytime when I accelerated the car in both live graphs are voltage dips at the same time. As the sensor is a new one I decided to lay some new wires from the connectors behind the battery (LHD) to the connector at the sensor under the car.
And now, you can believe it or not, the issue has gone. No further problems, No DTCs, no limb mode and the car runs great.
You can remember, my nightmare starts about 2 months ago with the DTC P0194 (fuel pressure sensor circuit erratic) and it ended with an issue in the wiring loom to the differential pressure sensor.
Many thanks to you all in the forum and many thanks to the IID Tool. And Not to forget this little gadget here in the Pictures:
The 5V simulator!
Without this simple device (built by dad last month) I wouldn't be able to make test drives with the car.
With this Gadget I could temporarily eliminate the PO194 DTC and the limb mode.
Best regards,
Thomas
28th Nov 2019 11:14 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5036
That's a great result Thomas, well done for getting it sorted and thank you for posting your results / outcome.
If only everyone who requested technical assistance on here would also post their final outcomes, so that all would benefit from the collective experience.yµ (idµ - eAµ) ψ=mψ
29th Nov 2019 1:09 am
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Update on my fault solution.
As you remember it was a short cut or loose contact in the wiring loom to gearbox and transferbox where also the wires for the differential pressure sensor are included. Some weeks ago while i was not in office due to covid 19, I decided to remove this problem wiring loom to check the fault exactly. It where some hard hours under the car and under the bonnet but than it came out. And now you can look the fotos:
12th Jun 2020 3:17 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Can you tell us what the loom was rubbing on?
12th Jun 2020 3:21 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
I found out someone of the former owners seems to have had the cabin from the chassis or the crossovers pipe removed or both.
The wiring loom normally is going behind the engine under the crossover pipe to the gearbox. But here it was over the pipe between the bulkhead and pipe squeezed.
!!!
Last edited by wedgev8 on 13th Jun 2020 4:25 am. Edited 1 time in total
12th Jun 2020 3:24 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5036
Yeah it should be behind the crossover pipe, it sits between the crankcase and g/box breather pipes.yµ (idµ - eAµ) ψ=mψ
12th Jun 2020 3:55 pm
slider_p
Member Since: 22 Dec 2019
Location: Brabant
Posts: 13
Hi @wedgev8 ,
That is a neat write up and awesome you found the problem!
Can you tell me which error codes you got before you started replacing the lpfp at first? I have P0087-00 and P2290-00 errors and some U-codes regarding gearbox and parking brake. I also have low readings on the LPFP and low Amps (2.8-3) it was using.
But after changing the LPFP I still have these problems.
I also have the issues only after warming up and also very randomly. The car drives absolutely fine. Until it cuts out.
The wire that was the culprit in your case; was the one that goes from the differential pressure sensor to the transfer case control ecu behind the battery?
8th Aug 2021 6:14 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Look in my post from november 29th here in this thread. P0194 and IT is the wiring loom from differential pressure together with some gearbox cable to the transfer ECU behind the battery.
I am very sure you have nö issue in the LPFsystem. I have the same readings at the LPFpump.
Check the Internal Module Operating Voltage 1 and 2 with your IID Tool while the limp mode comes Up.
Reading should be 5V .
And check and clean all earthpoints of the ECU and engine behind the right hand plastic wheel arch.
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