Thread: Which sensor now!

Originally Posted by 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

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...

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

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.

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

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

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


[quote=feraldisco]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...

Originally Posted by 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,