JimAttrill Posted June 23, 2008 Share Posted June 23, 2008 Hi all you TD5 fans (and Bogmonster) we have another TD5 auto that won't go. It starts wonderfully but accelerates so slowly, even in neutral, that you can fall asleep before it gets to 3000 rpm. Drives on the road as if the brakes are on. The turbo pressure eventually gets to the ok range according to the ECU. Many bits have been changed by the stealers, we also have swopped bits out from other cars and put it all back together as nothing makes any difference. Pump pressure is 4 bar as it should be, a new injector harness makes no difference, I have even remapped it to no effect. We did think it might be the throttle pots so changed that and then put the old one back. One thing I have noticed is that the ECU thinks the car is travelling faster than it is - a lot faster, reading 180kmph when the car has finally made it to 100kmph. Also, the Hill Descent Control light is permanently on. Will that cause the engine to run as if the brakes are on? This is not a new problem, the owner has moved the car from one workshop to another for the last 18 months but noone will buy the thing from him and he is getting desperate. I did suggest a box of matches Quote Link to comment Share on other sites More sharing options...
disco_al Posted June 23, 2008 Share Posted June 23, 2008 Also, the Hill Descent Control light is permanently on. Will that cause the engine to run as if the brakes are on? doesn't the HDC utilise the ABS system, could be part of the fault (not too clued up on the "new" stuff, but anythings worth a go) ? reading 180kmph when the car has finally made it to 100kmph. vehicle speed sensor fault on the 'box? are they standard wheels/tyres? if they are different size from standard won't that confuse the speed sensor into thinking it's travelling faster than it is? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 23, 2008 Share Posted June 23, 2008 The speed sensing on the Series 2 Discovery is calculated as the average from all four ABS sensors since all vehicles have ABS fitted there is no sensor on the transfer box. Oversize tyres will not make any difference to how fast the vehicle thinks it is going and are not going to affect it that much anyway unless you have 44" fitted It is a long shot but check the high-low sensor on the transfer box is operating properly - I am just thinking that it might account for both the reduced power and the f**ed up speed reading if the ECU thinks the vehicle is in low range? Maybe the gearbox is stuck in limp home mode though that wouldn't (shouldn't!) affect the revving in neutral Airflow meter been changed? not really sure but I hate faults like this and I am glad it is with you and not with me Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted June 23, 2008 Author Share Posted June 23, 2008 Changed the injecor harness, adjusted the injectors, changed the tappet cover gasket as it was leaking. Now the HDC light has gone out! Removed injector harness and put old one back in as no change. We substituted the air flow meter and it made no difference. Air flow tend to be low, as the engine doesn't go. How does this 'limp home mode' work? Can the pooter spot it? (we have a Rovacom Lite, though I know it has SLABS maybe we don't have the module for the gearbox). The engine does rev ---- eventually. There is none of the push in the back that you normally get from a TD5 as it hits 2000 rpm. Will check with the pooter as to whether it thinks it is in high or low. I do know that Sport mode has no effect at all. I give up for today and will go home and think about it. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 23, 2008 Share Posted June 23, 2008 The auto gearbox is a separate ECU to SLABS no idea whether the Rovacom has got it or not though. I think power may be restricted in limp home mode I know it drives like a dog as stays locked in 3rd gear which makes for very un-sprightly takeoffs Airflow was a "rule it out" thing so you have done that Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted June 23, 2008 Author Share Posted June 23, 2008 So, if it is possibly in limp home mode, how do we get it out of there? I did notice that the gearbox seemed to be always in the same gear no matter what you do. Although the display on the console shows different gears as selected they all feel about the same, ie very slow. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 23, 2008 Share Posted June 23, 2008 I think it probably needs the fault to be read, fixed and cleared to get rid of limp home but some may reset after an ignition cycle. The switch pack on the side of the gearbox is one common cause - if the ECU is getting a dud reading from the switch then it will panic and default to 3rd gear but you usually get an error on the dash, IIRC it reads "E" instead of the gear selected. Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted June 23, 2008 Author Share Posted June 23, 2008 No, it shows the gear selected ok. I am getting fed up with this one. Maybe the box of matches will be best Quote Link to comment Share on other sites More sharing options...
RangeyRover Posted June 23, 2008 Share Posted June 23, 2008 Ok, My old man had a similar problem on his TD5. No Electronic indications, but the problem for him was a collapsed exhaust catalyst blocking the exhaust output. A guy who is on here fixed it for him (Bell Auto services in york I think) Can't remember his forum name. It was fixed by opening up the catalyst, ditching the centre and rewelding back together (as I understood it) Maybe the same as you? RR Quote Link to comment Share on other sites More sharing options...
SteveRK Posted June 23, 2008 Share Posted June 23, 2008 Beat me to it! disconnect the exhaust down pipe from the manifold - blocked up? Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted June 23, 2008 Share Posted June 23, 2008 From memory the S and M lamps either flash or stay on if the auto box is in limp home.I looked at a TD5 110 Defender a couple of years back that a local LR indy had done a head gasket on,same thing - totally gutless.All readings on Testbook were good,fuel was at 4 Bar etc - could see nothing wrong.Luckily I had my spare set of "known good" injectors with me,so we put them in. Sorted,it flew along.Trouble was the owner simply would not pay for a set,so mine came out an it became a slug again. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 23, 2008 Share Posted June 23, 2008 Yes I think you are right on the S/M lamps had forgotten that! The injectors are a monstrous price! Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted June 23, 2008 Share Posted June 23, 2008 A mate who runs a local LR breaking business was very proud of the fact that he got £40 each for a set of 5 EUI's that he sold on the Bay recently.Bu--er,I would have given a bit more than that ! Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted June 24, 2008 Author Share Posted June 24, 2008 Ok, no S and M lamps on. So it is not in limp home mode, though it feels like it. There is no Cat. box of matches time soon ...... Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 24, 2008 Share Posted June 24, 2008 S and M One way of passing the time if you have no vehicle to get about I suppose Quote Link to comment Share on other sites More sharing options...
DaveA Posted July 8, 2008 Share Posted July 8, 2008 You probably already know this, but before changing gear the auto box ecu sends a "reduce power" signal to the engine ecu, until the gearchange is completed. Could this be "jammed", ie gear change not complete, or stuck in gear ? As already mentioned, the road speed comes from the slabs ecu. If this road speed was too high - wrong gear selected - reduction in power - one "confused" vehicle ......... Quote Link to comment Share on other sites More sharing options...
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