Weak Td5

[persod]

Hello down under!
I’m a swedish LR owner having performance issues with my Disco II Td5 -99, 240 000km:s. A bit of a long story but here it goes:
A few years ago the automatic gearbox was repaired by an experienced and well reviewed gearbox workshop. Everything was fine for about a year, then I noticed performance problems. Low speeds no problem, but impossible to maintain speed at even small hills, going down from 100 km/h to 70 making lines behind me and annoying other drivers. I suspected the gearbox again because of similar behavior before the previous box gave up, went to the gearbox workshop and was told there was only 6 months warranty on rebuilds but they took it for a spin and told me it was not the gearbox that was the problem. On a weekend I took a trip with the caravan and It was not a good experience. Had to abort as I had troubles getting up to speed, more than 70 Km/h was almost impossible.
So: I did the stall test and the gearbox instantly gave up, and so did I. Put the car in a garage for two years until I had gathered enough guts to do a gearbox change on my own. Bought a rebuilt one from Ashcroft with heavy duty converter. Spent a big and exhausting part of my time under the car, and while the box was away I also did some other maintainance. The new box wasn’t performing very well, rough gear changes mostly, a gearbox ECU replacement fixed that. Still not performing so I checked the oil level in the box and could fill almost two liters! A broken connection on the oil cooler was the reason, maybe the reason for the first two boxes gave up as well… After oil cooler exchange and oil fill the gearbox worked as it should, but still very bad engine performance. I have done most of the fixes for this problem but nothing gives me the performance expected. Uphills, even normal hills on the highway slows down badly. Pressing the pedal revs up the engine but no result on speed, just more revs. Fuel consumption is normal. No sign of diesel leaking from the injectors(oil level slowly decreasing as expected). Starts flawlessly, even running. No black smoke, no smoke at all really and normal CO2 at yearly checkups.


So far these fixes are done:
New fuel pressure regulator (x2, last time including the filter)
New MAF sensor
EGR blanking
Silicone hoses
Changed the injector harness (Yes, it was leaking oil badly so I also opened the ECU but nothing inside)
New waste gate regulator (x2)
New diesel pump
New air filter
Driving without mufflers make no difference


I have no errors on Nanocom
Links to Nanocom log files if anyone interested:


Engine: https://app.box.com/s/r3q3js3r9z184u95eup17lzuq0fui9dv (https://app.box.com/s/r3q3js3r9z184u95eup17lzuq0fui9dv)
Gearbox general: https://app.box.com/s/1dzgjif58t0pq0rw3hgc1cm4629adhad (https://app.box.com/s/1dzgjif58t0pq0rw3hgc1cm4629adhad)
Gearbox pressures: https://app.box.com/s/dlvzarrs0j4v8h9wxy1l3pomwj3b0h9h (https://app.box.com/s/dlvzarrs0j4v8h9wxy1l3pomwj3b0h9h)


Can anyone explain why all pressures except ”3-4 speed range 1” are at zero?
Are the accelerator voltages ok?
What have I missed? Please give me some advice. I was planning to keep this car for life, so I won’t give up.

[ozscott]

Hi mate. Can't help with TD5 issues but good to have you on board. You will find plenty of guys will offer assistance soon. Cheers

[RobMichelle]

Turbo related possibly

[persod]

Turbo related possibly

Yes, it sure could be, but nanocom log shows normal pressures if I'm not wrong. I can be going at 100km/h in lockup and when I get to a small hill it immediately gears down spinning the engine at +3000rpm, is that normal? Today I found that the wastegate lever was stuck and thought for a while I had found the problem, but no big difference after fixing it.

[Kaaaiju]

Try to check that the boost solenoid or by pass it all together, what brand was the fuel pump? Don't use anything but VDO as the cheaper ones pack up quicker,

Engine wiring not damaged or chaffing, maybe need to try another ecu, make sure the FRP filter isn't blocked even if it's new, check and clean it

There are some ideas, I am not expect but have to start somewhere

[bee utey]

Not a TD5 expert but if it was mine I would check the camshaft timing, injector clearances and use a mechanical pressure gauge to confirm the boost pressure.

[sierrafery]

Hi, according to the ECM data log it's not a management issue, the values are all OK so it can be fuel supply related, you said: New fuel pressure regulator (x2, last time including the filter)" , do you mean the small filter under the FPR or the main fuel filter cos you didnt say anything about that ... i know nothing about autobox correct data

BTW... what size are the tyres? ...cos if they are bigger than std and no remap an auto will behave just like you said without having any issue, better get a remap, untill then replace the depression control valve(LLN100140L) if you know it's old

[rick130]

Yes, it sure could be, but nanocom log shows normal pressures if I'm not wrong. I can be going at 100km/h in lockup and when I get to a small hill it immediately gears down spinning the engine at +3000rpm, is that normal?

Maybe the trans is stuck in Sport mode?

In normal mode it'll hang in and use the engines torque, in Sport mode it kicks down almost straight away when you use a bit of extra throttle.

[discorevy]

yes, data logs look normal, I'd also be looking at lack of fuel as none of your logs show anything above 3000 rpm , does it not make any power above this ?, this can mean second stage in fuel pump not working ( has been asked before but is it VDO), injector bump clearances , blocked filters , the heavy duty torque converters don't work too well without a remap but I think you need to sort fuel first.

[DazzaTD5]

*Remove the air intake tube that connects to the turbo and put ur fingers in and see if the turbo fins spin freely, obviously with engine NOT running.
*Disconnect the waste gate actuator rod off the spindle on the exhaust manifold and see if the waste gate opens and shuts freely, if not lube with something like Lanolin spray and open/shut open/shut until it is free.
*As already noted, disconnect turbo modulator and run a line straight from inter-cooler pipe to turbo waste gate actuator.

[rover-56]

Check your fuel pump.
Engine will draw enough fuel to run with a non working pump, but not above 3000rpm.
Good luck, and welcome.
Terry

[persod]

@sierraferry: Yes, I replaced the small (and unreasonably expensive) filter under the FPR, and also the fuel filter behind the wheel, which I change regularly. The tires are not oversized, and I have checked and lubricated the wastegate actuator arm which indeed was stuck and I thought I'd found the problem but no difference[bigsad]. The new fuelpump is not a VDO, but today I connected a pressure monitor to where the fuel temperature sensor sits in the FPR and the pressure is well above 4 bars, almost 5 even when driving at high load uphills, no decrease at all in the pressure monitoring. BUT: strangest thing, with the pressure monitor connected It was performing wonderful, could even accelerate uphills! So, I put the fuel temp sensor back and the problem was back... disconnected the contact from the sensor and Voila! Perfect preformance!!
Bad sensor or something corrupt in the ECU. I am suspecting the ECU since I also found an error message from the gearbox: "P1884 CAN MESSAGE MD_IND INVALID" (no other errors), and strange Engine temp data from gearbox:
139796
It never goes above 53 degrees...

So now I'm contemplating how to proceed? New temp sensor? New ECU? Other Ideas? Are there any negative effects driving without the temp sensor connected?[bighmmm]

[AK83]

So you disconnect the fuel temp sender, and it goes good.
Reconnect the fuel temp sender and it goes bad.
But you're getting engine temperature values from the gearbox temp sender?

Is this an OBDII tool you're using to get this data, or the nanocom?(looks like nanocom, but need to ask question).

I'd say drive with the fuel temp sender disconnected for a while and see how you go.
But before you condemn the ECU, pull some stuff off around it and triple check the wiring loom to the ECU for damaged parts or shorts.

My brother's TD5 had an issue a while back and I thought it was ECU related. So when searching on the issue I found that damaged ECU looms are not so uncommon.
Maybe the wire from the fuel temp sender is cross contacting with another wire before it gets to the ECU and therefore the ECU gets corrupted or scrambled data.

Alternatively: when you changed the fuel pressure regulator, did you change the entire assembly or did you rebuild your old one with some new parts(eg. regulator/o-rings/gaskets etc) and keep the body of the assembly including the temp sender?
I think many people assume that when you do the FPR, you buy the new assembly in it's entirety, which means an entirely new body, hoses .. ie. an entirely new part, which includes the temp sender.
If you used your old fuel temp sender to rebuild your FPR, maybe the sender is dead, giving a high reading on the fuel temp and confusing the ECU?

[steve_a]

Red herring first - the temperature reported in nanocom for engine temp from the gearbox is rubbish. I have *no* idea where it comes from but it is never the actual engine temp. There is also no temperature sensor on the gearbox.

The error message on the box I see quite often on most of the D2s I've hooked my nanocom to, it usually indicates a low voltage at some point - I swear the box can log a fault during cranking....

It sounds like you have the fault found though, check the fuel temperature in the TD5 engine section of nanocom, I'm guessing it is reading high and so the ECU is reducing the fuel being fed in because of the perceived temperature. Disconnected the ECU just assumes a default value.

[discorevy]

Ditto eng temp from gearbox values, its just a reference value.
You can swap eng temp sensor with the fuel temp sensor to eliminate that ( clean first :-)

[persod]

I read values with Nanocom Evolution. From what I've found, the Engine temperature reported from gearbox is received from the engine ECU and is used by the gearbox to determine if it's warm enough to engage lockup.
My fuel temperature sensor seems to give correct values?:
139829
...and the coolant temperature follows the same curve. When disconnected the fuel temp value defaults to 60 degrees.
I'll have a closer look at the cables

[BennehBoy]

The temp senders don't normally fail outright, they tend to flatten off with age reporting values lower than reality, typically 10-20C less. At least when using Bosch parts.

For the coolant sensor this normally manifests as increased fuel consumption.

I've not had a problem with the fuel sender yet, but would imagine it would not retard performance in this failure mode (on a manual at least!) - looking forward to seeing the outcome of this investigation though as I'm not sure how/if the auto ECU uses the fuel temp information and whether this is actually a wiring issue.

If you've got a multimeter to hand you can test the sensor by setting it to resistance (~20kohm) and referring to this datasheet to approximate temperature from the output -> http://www.bosch-motorsport.com/media/catalog_resources/Temperature_Sensor_NTC_M12_Datasheet_51_en_2782569 739pdf.pdf

[ledge67]

If you believe your problem is the ecm, replace all of the power feed and earth wires running to the ecm. You don't need a loom, just replace them individually. I haven't had it on a Td5, but too many times to count on trucks.

[persod]

@BennehBoy (https://www.aulro.com/afvb/members/45391.html)

I think you are right. According to the Nanocom manual, fuel temp should be about 10 degrees below coolant temp, mine measures approx. 30 degrees below. The fuel temp is used by the ECU to calculate fuelling so this might be it! I have ordered a new sensor, not so expensive and since I've replaced everything else....[biggrin]
Will update when I've replaced it.

[BennehBoy]

Fingers crossed.

[persod]

So, I finally got the new temp sensor. Temp readings are now accurate, approx 10 degrees below coolant temp and the engine runs better, but still - best result with the fuel temp sensor disconnected! Don't know how to interpret these results. Is it a fault in the ECU? For now I prefer driving with disconnected sensor, but it bugs me. I would really like to get this working with the sensor connected, but there is a significant loss in power, although better than with the old sensor. What do you guys think?

[bsperka]

So, I finally got the new temp sensor. Temp readings are now accurate, approx 10 degrees below coolant temp and the engine runs better, but still - best result with the fuel temp sensor disconnected! Don't know how to interpret these results. Is it a fault in the ECU? For now I prefer driving with disconnected sensor, but it bugs me. I would really like to get this working with the sensor connected, but there is a significant loss in power, although better than with the old sensor. What do you guys think?Hmmm... just putting it out there.....could the fuel temperature sensor be faulty.....

[sierrafery]

You should record two data logs, one with the sensor connected and one with it unplugged and post them here

[harro]

Fuel temp sensor will reduce fuelling when cold to compensate for the higher density of the diesel.
If the sensor is working properly you will need to get the engine up to normal operating temps and then compare connected with disconnected sensor.
Default in the Ecu for the fuel temp is around 70c iirc.

edit; just checked and the default is 60c.

Paul.

[sierrafery]

Might be a glitch in the fuel map if the sensor reading is OK but the engine behaviour is not, the FT sensor's input has a very complex effect, here's the info: Fuel Density Compensation maps | DiscoTD5.com (http://www.discotd5.com/td5-tuning/fuel-density-compensation-maps)

[persod]

You should record two data logs, one with the sensor connected and one with it unplugged and post them here

Took her for testdrives today, and logged the data. Drove the same short strip twice, trying to stay at 90 km/h. The drive ends with a climb, not to steep. Without sensor it stays in lockup the whole way to the top, preserving speed (almost), but with the sensor connected it leaves lockup early and then gears down to third. Don't know if the data gives any useful information but here are the files:141372141373

[sierrafery]

I'd put a new coolant temp senor too if i was you cos it seems it reads low as well, or at least swap the ECT with FT sensors for test... is the new FT sensor a good brand?