I had a play with my non-BT IID Tool today on the commute home. I set it to display Torque Converter status. I found that it was "open" at low speed up to approx. 30mph, was "closed" at constant or slow rate change throttle applications above that speed. "Regulated" appeared when asking for some proper acceleration. This was usually accompanied by a slight jolt as the box changed down to give me acceleration. I note that your jolt occurs at precisely the point that the clutch goes to regulated mode.

I note that "regulated" appears during gear changes - which is as it should be. The clutch is slipped slightly to, supposedly, give smoother changes. I guess the jolt occurs because the clutch/revs mapping isn't spot on. Perhaps a tired clutch is the culprit. My gearbox was "Geoff-flushed" last year and has done about 15k miles since I think.

I reckon there's a calibration issue somewhere. Not sure if it's fixable without major work - perhaps one of the gurus can tell us if the gearbox can be updated/calibrated. I know the centre diff clutch can be calibrated but I don't think that's an issue here as in "special programs off" mode that we use on tarmac the centre diff is basically unlocked anyway, as I understand it. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

RRSTDV8 - so it seems your TC is working almost correctly apart from poor shift quality?

Did it seem slightly worse than normal with the IID Tool reading live values? I ask because it seemed that way when I used the non-BT version of the tool (Gap themselves warn about erratic behaviour when monitoring live values).

May just be my imagination but the BT version of the tool doesn't seem to cause the same amount (if any) of erratic behaviour whilst live values are being monitored.

You could use your IID Tool to reset the gearbox adaptations and calibrate the Transfer box clutch? (the latter seemed to make my vehicle run a little more smoothly). 2008 MY Java Black TDV8 HSE

I don't know whether my TC is working properly or not. The whole drivetrain seems quite laggy at times. It feels like old fashioned 1980s "big turbo" response to the throttle; throttle pressed, nothing, nothing, woosh. I suspect EGRs but I have no error codes or other indications of a problem.

I'm not sure there was a difference when running with live values shown but I wasn't paying attention to it other than to see the clutch status.

I have done gearbox adaptations resets before with my IID and must say that it didn't make any noticeable difference. I haven't tried a transfer box calibration though.

As an aside, it is possible to calibrate the transfer box without a diagnostic tool of any sort. There is a "magic procedure" in the workshop manual. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

"As an aside, it is possible to calibrate the transfer box without a diagnostic tool of any sort. There is a "magic procedure" in the workshop manual."

Tried that - didn't work for me. Others have reported the same IIRC. Maybe it only works on earlier vehicles?

The 'throttle lag' that you are experiencing - is it all the time or just once in a while? Normally mine responds instantly to throttle but just occasionally I feel a similar lack of response - as if the car is in neutral then it thumps into gear and takes off.

Happened yesterday on entering a roundabout: so going from brake to gas at low speed. Was logging live values of TC at the time and the log shows the TC going in and out of lock more than once. So although it feels like neutral it is really just the TC locking and unlocking.

Perhaps it only occurs if I ask for acceleration just as the TC does its 'inappropriate unlock' thing. 2008 MY Java Black TDV8 HSE

Sorry - this is becoming a bit of a 'nerdfest'

But here is the log referred to in last post:

http://www.rrsport.co.uk/gallery/albums/us...35_Log.pdf

You can see at 725 seconds where the speed is at its lowest after slowing to enter a roundabout I accelerated at 728 secs and the TC stays unlocked and eventually goes back to regulated at 735. Somehow the speed picks up even when the TC is unlocked. The EGR valves go from closed to open and for good measure there is a small spike in the battery voltage of about 0.2 volts.

This is the little section of the log being discussed:



Sadly I've not much idea how significant any of this is

But I'll persevere with logging some other values to see if there is anything else happening that might throw a bit more light on the problem. 2008 MY Java Black TDV8 HSE

The speed can increase with the TC clutch unlocked - it's behaving as a traditional automatic at that point so you get a "slushy" response. When the clutch closes there is direct drive from engine to gearbox - effectively bypassing the TC as I understand it - in order to improve fuel economy and emissions. The EGRs opening at that moment won't be helping matters as the engine will be breathing "dirty" air just when you're asking for some performance.

The dull performance I experience is a bit like the all-too-familiar "suicide pause" that we all experience when pulling away from junctions etc. Except it happens at normal speeds, usually when cruising along on a partial throttle and then asking for some poke. If I'm "making progress" it usually doesn't delay and I get the lovely grunty TDV8 acceleration we love. I'm increasingly of the opinion that the issue is related to the EGRs. I wonder if the EGR values logged by your IID are the actual EGR % or actually just what the system has asked them to do. That is, I wonder if the system is saying "close now please" and the valves are actually being slow/ineffective in closing resulting in poor throttle performance. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

I'm not seeing 0.2v voltage spike or really anything odd in the alternator trace.

I'd pick a throttle, an EGR, RPM, TC, and the clutches A,B&E as live values and repeat the exercise.

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Thanks for the input guys.

Robbie- I have another trip to do on Friday so will set the live values you suggested and see what it reveals.

On the return trip I'll try the MAP and MAP values perhaps as these are alleged to be involved in TC clutch control? 2008 MY Java Black TDV8 HSE

Robbie wrote:

I'm not seeing 0.2v voltage spike or really anything odd in the alternator trace.

I'd pick a throttle, an EGR, RPM, TC, and the clutches A,B&E as live values and repeat the exercise.

Well: as suggested - recorded another log in steady cruise conditions with different variables. My IID Tool doesn't offer me live values 'Clutches A,B&E' or anything else called a clutch so I just chose Solenoids 1 to 4 plus accelerator pedal position sensor 1, engine speed, EGR valve 1 and TCC.

Edit: - checked the manual and it seems Solenoids 1- 4 are Clutches A, B, C and D + E respectively

When the 'jolt' occurred I stopped the recording as soon as I could. You can see from the log linked below that the TCC went from closed to open and back to regulated starting at 656 seconds. But something odd was happening before that at 604 seconds. There were changes in solenoid pressures and although the engine speed was constant there were some odd changes in accelerator pedal position (but I don't think I was moving the pedal).

http://www.rrsport.co.uk/gallery/albums/us...cruise.pdf


What I am struggling to understand here is if any of the changes are causing the TCC behaviour or just reacting to it.

To help with viewing on tablets - I'm attempting to attach here a snapshot of the log when the jolt occurred with the variables labelled so it makes sense to anyone who can't see the whole pdf on their device.

Click image to enlarge

 2008 MY Java Black TDV8 HSE

Be interested to see if both throttle pedal sensors show the same movement. It appears that the car is responding to what it thinks is a rapid application of throttle and is closing the EGRs and doing the stuff you'd expect it to do when you ask for some beans. I wonder if you have a throttle pedal issue...hopefully Robbie can make more sense of it than my feeble attempt  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

"I wonder if you have a throttle pedal issue..."

Fairly confident I don't because I've already replaced the whole assembly (APP).

However - one of the electric throttles could cause the same?

Just been reading the workshop manual section on the TCC control and it seems Solenoid 6 controls the two spool valves that lock and unlock the TCC so that's where my suspicions lie now. Could be either the Solenoid or the TCM sending inappropriate signals?

Good game though - it's one way to learn about diagnostics! 2008 MY Java Black TDV8 HSE

Can you send me the full pdf and export the log as a CSV file so I can spin it in excel?

I do have something in mind but I may get someone to look at it.

PMs work best for me, or just drag me from the D3 / D4 forum.

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Some background reading:

http://disco4.com/forum/topic108824.html

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Hi Robbie,

Thanks for the offer of further help

Sent you a PM with the full pdf but I can't figure out how to send you the .csv file. When I try to upload it I get a message saying it is a 'forbidden file extension'.

Maybe I am just being dumb (likely) so if you or someone else can tell me how to send the .csv file with a PM that would be great.

The further reading looks a bit worrying - but my symptoms are nowhere near as bad as those described. I first changed the gearbox fluid at around 35k but of course don't know what may have happened to it before my ownership. A garage that serviced it before I bought it mentioned that there was an oil leak from the transmission that the PO didn't bother to have anything done about. No leaks since I have owned it - so must have been fixed but maybe run with insufficient oil in the past?

Thanks again, 2008 MY Java Black TDV8 HSE

I've had a chat around and your issue has caused some head scratching. Current thinking includes a possible software glitch causing an erroneous command (I'm not convinced with this option), a mechatronic leak releasing pressure or a mechanical issue with a stator bushing changing the applied pressure.

Perhaps an extended datalog to see how often the glitch happens to see if there is a pattern to it, but I think you need a visit to a gearbox specialist for diagnostic time.

It's in interesting one. Land Rover - Turning Drivers into Mechanics Since 1948

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