Which sensor now!

[SO69WA]

Afternoom all!

Can someone please tell me what their td5 disco does when you disconnect your coolant temp sensor, while running and up to operating temp

[Psimpson7]

Cant go and test mine now, but from memory if it thinks the sensor has failed it checks it against the fuel cooler temperature and gets a calculated value for teh gauge.

[SO69WA]

thanks, your right by what the workshop manual says, but need to know what happens in reality, mine drops to a 1/4 on temp gauge and raises revs as if the motor on choke cycle indicating the default feul temp is not working.....


The inputs and outputs for the FT sensor are 5 volt supply and signal out. In the event of component failure the ECM
reverts to a fixed value of 60 °C stored in its memory.

looking forward to your reply

[Psimpson7]

Ok, Ive just been out and tested it on mine (Defender not D2)

The car is warm, but not hot, and I havent got the time to pop out to get it hot now.

When I removed the plug the gauge dropped right down, although it still seemed to run happy enough.

the WSM lists a number of possible symptoms if the sensor fails inclding driveability concerns

[SO69WA]

thanks mate, much appreiciated,

your idle didnt increase?!,

reason i ask is when started from cold my truck is relatively smooth through the rev range, but when up to op temp, feels off key beween 2500 to 3000rpm, like the timing is out on an old petrol donk , then retuns to normal percieved opp at 3000+rpm with cammed kick in the pants,

replaced MAF and that got rid of hesitation hicups under hard acceleration, but this retard zone still prevails

[Psimpson7]

Hi,

Correct, I got no increase in idle atall, but as I said it wasnt hot, only warm (water temp of about 60 degrees)

Rgds
Pete

[Graeme]

If the D2 TD5 coolant sensor is disconnected, the temp gauge needle should drop to the bottom and the high temp warning light should be on. That's the LR specified and observed (by me) indicator of the coolant sensor with out-of-range resistance. If the needle is only going down to 1/4 then I'd start by looking for oil in the ecu harness at the ecu affecting the resistance of the coolant temp circuit.

[Redback]

thanks mate, much appreiciated,

your idle didnt increase?!,

reason i ask is when started from cold my truck is relatively smooth through the rev range, but when up to op temp, feels off key beween 2500 to 3000rpm, like the timing is out on an old petrol donk , then retuns to normal percieved opp at 3000+rpm with cammed kick in the pants,

replaced MAF and that got rid of hesitation hicups under hard acceleration, but this retard zone still prevails


Try cleaning the AAP sensor (on the side of the airbox) be careful with this sensor they are very expensive, contact cleaner is best, also clean the EGR as this can get clogged with oil and soot.

Oil in the injector harness will cause rough running, check this as well.

Check the wastegate modulator for cracks in the hoses and also check the modulator itself.


Baz.

[SO69WA]

thanks for the feed back,

my concern is the fuel temp sensor opp properly, as its the sensor the ecu reverts to if the coolant sensor fails and then in theory the ecu reverts to a set value of 60'c, in the event the fuel sensor fails, hence my thinking that on light throttle when warm theres a mismatch in fine tune fuelling, i would disconnect/change the sensor to confirm but its a absolute pain to tinker with gven its location so will have to pony up for mechanic intervention, if we conclude its suss


In the event of component failure the ECM calculates coolant temperature from the fuel temperature sensor signal. If
this occurs, the limit engine operation if coolant temperature is too high becomes inoperative.


Fuel Temperature (FT) sensor

The FT sensor is located at the rear of the engine in the fuel rail with the tip of the sensor inserted at least 10 mm into
the fuel flow. This allows the sensor to respond correctly to changes in fuel density in relation to fuel temperature.
The FT sensor works as a NTC sensor. As fuel temperature rises the resistance in the sensor decreases. As
temperature decreases the resistance in the sensor increases. The ECM is able to compare the voltage signal to
stored values and compensates fuel delivery as necessary for hot engine start.
The operating range of the sensor is -40 to 130 °C (-40 to 266 °F).

Input/Output

The inputs and outputs for the FT sensor are 5 volt supply and signal out. In the event of component failure the ECM
reverts to a fixed value of 60 °C stored in its memory.


FYI have cleaned AAP, MAP, disconnected EGR for diagnostic, no change, replaced MAF,

how much is a new Harness, do you have to see oil at the plug end to be suss or can the problem exist before that,

[SO69WA]

OH and i have replaced wastegate modulator, well ... borrowed one which i have to give back otherwise ill have to pay for it.

this truck is quite smooth, test drove 5 before i bought this one, which makes this anomally of vibration and dullness @ 2500- 3000rpm at part throttle a pain, if i stick my boot into it it kicks back and fair flies ,

also at rest and bring revs up( no boost!?) the same trait exists, interestingly in this zone 2500-3000,it doesnt quite rise in revs incremently like any where else, and can seem to hunt and surge 100rpm, yet foot flat, it revs cleanly.

whats the chances the throttle could be responsible

[Graeme]

how much is a new Harness, do you have to see oil at the plug end to be suss or can the problem exist before that,
Best to check the plug at the front of the head, as oil can travel to various sensors as well as to the ecu. Its been seen at the MAF and crankshaft position sensor connections at least. It can affect the operation of those sensors even if it hasn't yet reached the ecu plug.

Checking revs for varying throttle positions without any load is inconclusive, but your 1/4 temp with coolant sensor disconnected is a real indicator of a faulty sensor circuit or ecu.

[LandyAndy]

Hi SO69
Have you had the ECU read for faults via Nannocom or similar?
Mine is showing a fault in the temp circuit,when I had it in Perth,Marc at Beechboro 4x4 said I was getting 4degC difference between the coolant sensors and suggested a new coolant sensor be fitted.Nanocom only tells of the fault,he picked the temp sender differences with his Auto-Logic whist fitting my new chipped ECU.
Another check for oil in the harness,remove your ECU(its next to the battery) Is there any oil leaking from the RED plug,if so you need to replace the injector harness inside the rocker cover.Its an easy DIY job,harness is around $200 to $250.
Im in Williams,I can read your ECU and check the wastegate adjustments via Nanocom if you cant find anybody closer.
See the list of people with diagnostic equipment in the sticky section at the top of the Electronic Diagnostics Forum.
Andrew

[SO69WA]

thanks gents

the harness (on a 2003 disco) may be the culprit, does there seem to be an observed service life of these, and are the new ones better insulated, than the originals

i will look into the nanocom, is it the best dianostic for the price?,

[Graeme]

The injector harness in my my03 is original and hasn't leaked in almost 210k kms but that just means its a good one - so far anyway.

[Blknight.aus]

might also be the crank angle sensor connector.

[SO69WA]

Thanks again for your input, muchly appreciated,

always pays to be diligent in proceedure, undid the injector harness and sprayed with cleaner on main harness conector and oil bubbled out, pulled red plug off ecm, (Checked Last time 4weeks ago to put on Dp chip) now oil every where,over dp conectors as well,

new harness orderd, and does run far better with contacts clean at this stage,

WOO HOO!!!

[SO69WA]

An UpDate for all

No the loom alone did not, and im still wiping oil out of the harness, almost all gone,

a test on a nanocom, as well as testbook, picked up a driver demand error, re Accelerator.

New Accelerator, $400 fitted and programed in, and now drives like i expect it to.

in fact with the DP Chip its sweet, revs to 4250 and very linear

i must say though it appears that the rover programing is similar to mercedes in that if you put your foot down there is a delay 0.5-1.0 secs, before full power is allowed, separate to full boost.

i will now get the engine mounts looked at as im sure that the vibration is now harmonic in nature

[Grumpy]

An UpDate for all

No the loom alone did not, and im still wiping oil out of the harness, almost all gone,

a test on a nanocom, as well as testbook, picked up a driver demand error, re Accelerator.

New Accelerator, $400 fitted and programed in, and now drives like i expect it to.

in fact with the DP Chip its sweet, revs to 4250 and very linear

i must say though it appears that the rover programing is similar to mercedes in that if you put your foot down there is a delay 0.5-1.0 secs, before full power is allowed, separate to full boost.

i will now get the engine mounts looked at as im sure that the vibration is now harmonic in nature

Was going to ring you to see what the out come was. Glad to hear the stutter - for want of a word - is fixed. Still a bit woried about the front uni's tho.


Tony :wheelchair:

[SO69WA]

Ta Tony,

yes, now i will be doing a full lube throughout, ill let you know if theres any play,

once again thanks for your time and effort, muchly appreciated,

Happy New year,

Cheers Stuart

[Grumpy]

Ta Tony,

yes, now i will be doing a full lube throughout, ill let you know if theres any play,

once again thanks for your time and effort, muchly appreciated,

Happy New year,

Cheers Stuart


No worries Stuart,
Wouldn't hurt to get a wheel right off the ground so you can rotate the shaft. Mine didn't show up in one position however, when I rotated it about 90 degrees, was it loose! Read st****d
You most probably know that anyway.

Yes, its not to late is it?

Happy New Year,

Tony :wheelchair:

[Gold_TD5]

revs to 4250



WTF, mine has never been over 3000, I must be babying it:(

[feraldisco]

An UpDate for all

No the loom alone did not, and im still wiping oil out of the harness, almost all gone,

a test on a nanocom, as well as testbook, picked up a driver demand error, re Accelerator.

New Accelerator, $400 fitted and programed in, and now drives like i expect it to.

in fact with the DP Chip its sweet, revs to 4250 and very linear

i must say though it appears that the rover programing is similar to mercedes in that if you put your foot down there is a delay 0.5-1.0 secs, before full power is allowed, separate to full boost.

i will now get the engine mounts looked at as im sure that the vibration is now harmonic in nature

Hi - when you look up symptoms for throttle position faults, most of them seem to relate to idling problems. I'm curious to know if your vehicle also had idling issues. My Disco has exactly the same revving/power delivery problems as yours had, but no idle issues and no TPS faults registered on Nanocom. Before I fork out $170 for a new throttle/sensor assembly, plus pay someone to program it, I guess I'd like to get a bit more confirmation that this is actually the problem. Mind you, I've just about replaced all other likely contenders - loom, MAF and turbo boost modulator, so what's another one! One day I'll get the full benefit of the 85rwkw that the vehicle gets on the dyno...

[SO69WA]

Innitially, the engine, when up to op temp was running rough and thats what got me into chasing my tail,

so systematically i went through all sensors to see how they made the engine perform when not active,

and what sensors made a significant contribution to the engine whether the engine was hot or cold, and if faults logged as expected,

intruth, i free reved it alot to duplicate the poor running/ vibraion not rolling, to discount drive train, thats when i discoverd the flat spot / revs fluctuating, interesting!!!, so when the driver demand fault logged i made a note, as i didnt do it,

originally i thought suss as you free rev the engine and held revs at say 2750, if you really slowly depress the throttle further, the revs would not rise, and in some cases drop 50, and then hunt 100 rpm, not normal!!!,

initially i was told it was the turbo cavitating- BS as turbo does not boost until loaded, fuel starvation- BS as free rev is light load, it had to be a computer issue, with really the sensor first asked being the issue?!!!

It always idled fine, apart from when i removed the coolant wire and then it rose but still smooth and civillised,

The Fault did not register all the time, but during the number of diagnosis sessions it was noted as the only sensor fault that would come up that i didnt create,

Oil in the loom complicated the search, and i now believe the vehicle would cool down during the oil wipe out proceedure giving the impression it was fixing it,

the engine definitely runs significantly better than before with the accelorator replaced, ie like youve just given the injectors a clean, sharper, more responsive,

it appears these may have a shelf life and do wear, differently maybe, but do wear regardless, engine now free revs as you would expect,

it still vibrates alittle more than i would like when really hot, but i think now it could be mounts as i can drive to Geralton and it runs fine, but as soon as stop start driving starts in town it deteriorates, & having clutch fan active and air con on speeds up the process, but do not directly contribute to the vibration,

as revs rise the vibration decreases as per engine harmomics, hence my thinking a hot engine mount not isolating the engine as much under max tourqe

[SO69WA]

General

An engine control module (ECM) controls the five-cylinder direct injection diesel engine, and works on the drive by
wire principle. This means there is no throttle cable, the ECM controls the drivers needs via a signal from the Throttle
Position (TP) sensor on the throttle pedal.
The ECM is a full authoritative diesel specific microprocessor that also incorporates features for cruise control and air
conditioning control. In addition, the ECM supplies output control for the exhaust gas recirculation and turbocharger
boost pressure. The ECM has a self-diagnostic function, which is able to provide backup strategies for most sensor
failures.
The ECM processes information from the following input sources:

l Mass air flow sensor.REPLACED, improvement in topend performance

l Ambient air pressure sensor. CLEANED no Change

l Manifold absolute pressure/inlet air temperature sensor.CLEANED No change, rougher when disconected

l Engine coolant temperature sensor.CHECKED, WORKING

l Crankshaft speed and position sensor.WAS MY next bet if throttle pos sensor ok

l Throttle position sensor. REPLACED, Good Improvement in Drivability

l Fuel temperature sensor.Replaced no Change

l Air conditioning request.

l Air conditioning fan request.

l Brake pedal switch.

l Clutch switch.

l Cruise control master switch.

l Cruise control SET+ switch.

l Cruise control RES switch.
l High/low ratio switch.




ENGINE MANAGEMENT SYSTEM - TD5

18-1-18 DESCRIPTION AND OPERATION

Throttle Position (TP) sensor – Up to VIN 297136

The TP sensor is located on the throttle pedal assembly. It detects throttle pedal movement and position. It uses two
position sensors to provide the ECM with the exact throttle pedal position. As the pedal operates the voltage of one
position sensor increases as the other decreases.

Input/Output

The ECM provides the throttle position sensor with a 5 volt reference feed. Both position sensors send an analogue
signal back to the ECM.

l Sensor one, 0 to 5 volts variable.

l Sensor two, 5 to 0 volts variable.
Input to the throttle pedal position sensor is via pin 14 of the ECM connector C0658. Output from sensor one is
measured via pin 12 of the ECM connector C0658. Output from sensor two is measured via pin 36 of the ECM
connector C0658. The earth path is via pin 26 of ECM connector C0658.


The TP sensor can fail the following ways or supply incorrect signal:

l Sensor open circuit.

l Short circuit to vehicle supply.

l Short circuit to vehicle earth.

l Water ingress.

l Sensor incorrectly fitted.


In the event of a TP sensor signal failure any of the following symptoms may be observed:

l Engine performance concern.

l Delayed throttle response.

l Failure of emission control.

If the TP sensor (COMPLETELY) fails, the engine will only run at idle and the MIL will remain on until the fault is eliminated. Turning
the ignition off/on can reset the MIL provided that the fault has been rectified.

[LandyAndy]

Hey Gold TD5
You havent experienced the boost cut out on a chiped TD5!!!!!
MATE THERE IS MUCH BEYOND 3000!!!!
Andrew

[SO69WA]

OK, your reference to the cruise cut out, does seem to vindicate the TPS,
this cut out is it load dependant, like up a hill / air con/ towing, or does it do it hot and/or just after a cold start, is it like turning the engine off, or a stall in power delivery, in my experience turbos rarely fail in a lightswitch type effect, they either have full power or a shade of it, never like an ignition cut,


[QUOTE=feraldisco]thanks - I'll make sure turbo wastegate is operating correctly (I have a new turbo boost modulator but I'm not convinced the actuator is working properly, even though these apparently never bugger up) first and may revisit TPS. The thing that makes me think it's not the TPS is that I've never received a 'driver demand' error and the engine still cuts out a bit under cruise control.

cheers

[SO69WA]

was it doing it before the chip, and does it do it worse after flogging the car, what is your fuel consumption?



hoses are ok, no soot when trying to rev it passed 2500 (only occasionally get soot when accelerating hard from lower revs and between gear changes, but put this down to new chip).

It's a 99 manual with only 140,000kms and I know that the motor itself is in good nick as it's super smooth (smoother than any other Td5 I've driven) under 2500 and it gets 85wkw on the dyno (usually only get 75-90wkw from a TRS chip). I run a snorkel with standard paper filter, but thinking about getting one of the Td5Alive foam air filters...


[QUOTE=SO69WA]Yes its possible there is more than one battle being fought here, and i do think that the tps should be a serviceable item changed every 5 years min, ie like sparkplugs they still might run , but gees do you notice when you put new ones in.

turbo problems are rare indeed, given the unit we run, providing its well oiled and exercised often, normally blown or caviating/ delaminating inlet hose are the issue here, so check them, see if you can verify wether at these low power moments, there is excesive soot from the exhaust in the rear view

does the issue occur if you leave your foot flat,

oh are you manual or auto, do you have snorkel and clean wet type air filter, how many ks and who were previous owners

[QUOTE=feraldisco]It's a constant issue pretty much, hot or cold and in all gears - runs rough and just doesn't accelerate smoothly between 2500 to 3000...will sometime accelerate hard beyond 3000, but sometimes just rough and no extra acceleration without really pushing it. I don't think the turbo itself is the problem, but it's possible that the ECU is cutting power due to sensing overboost. I've replaced the turbo boost modulator, freed up the wategate and played around with wategate rod length - none of which seemed to make much difference. It may be a faulty wastegate actuator/valve and I'll test this on the weekend. Don't think it's a fuel problem as fuel pressure is fine. Will test MAP, AAP, TPS and wastegate valve more thoroughly. Tempted to just replace TPS anyway for $170...


[QUOTE=SO69WA]OK, your reference to the cruise cut out, does seem to vindicate the TPS,
this cut out is it load dependant, like up a hill / air con/ towing, or does it do it hot and/or just after a cold start, is it like turning the engine off, or a stall in power delivery, in my experience turbos rarely fail in a lightswitch type effect, they either have full power or a shade of it, never like an ignition cut,

[SO69WA]

well they upgraded the two track TPS on your 99 to a three track on mine, update 2003 so we can rekon theyre suss and may indicate why your symptoms are more severe, my three track was spose to verify its pos, and maybe be more robust but obviously can still crap itself as well,


ENGINE MANAGEMENT SYSTEM - TD5

DESCRIPTION AND OPERATION 18-1-19

Throttle Position (TP) sensor – From VIN 297137

Discovery Series II vehicles from VIN 297137 use three track thick film potentiometers. No idle speed sender switch
is used on this type of sensor because the ECM can compare the two or three sets of signals to implement idle speed
control and over-run fuel shut-off. The two potentiometers are known as track 1 and 2 potentiometers. The track 3
potentiometer on later models is used to improve the resolution of the pedal. The ECM provides a 5V supply and
receives a signal from each of the potentiometer tracks.

a = Track 1

b = Track 2

c = Track 3

d = Voltage

e = Pedal angle (degrees)

f = Wide open throttle stop tolerance band

g = Not applicable for Discovery Series II.
With reference to the above graph, at idle (throttle released), track 2 returns a signal of 4.2V to the ECM and track 1
returns a signal of 0.8V. The ECM calculates the sum of these two figures which totals 5.0V.
At wide open throttle, track 2 returns a signal of 1.1V and track 1 returns a signal of 3.9V to the ECM. The ECM
calculates the sum of these two figures which totals 5.0V. The ECM uses this strategy to error check the TP sensor
signal and ensure that the requested throttle position is applied. The third potentiometer track measures the tolerance
of tracks 1 and 2 and provides an improved functionality check of the pedal angle.

NOTE: Three track TP sensors cannot be fitted as replacements on vehicles previously fitted with two track TP
sensors. Replacement ECM's are configured for two track TP sensors and can be fitted to all Td5 models. When
replacement ECM's are fitted to vehicles using three track TP sensors, TestBook or T4 must be used to configure the
ECM for three track TP sensor use.
If the TP sensor fails, the ECM will illuminate the MIL and the engine will operate at normal idle speed only.

[QUOTE=feraldisco]yep, same roughness/struggling characteristics before and after chip - the chip has just given me a bit more bottom end oomph as I can't really access over 2500! Hence I also get rather good fuel economy and it's not really an options to flog the car, as short shifting is a necessity - it feels very coarse and unpleasant over 2500 so I don't like going there...