Using disco 2 td5 auto in manual mode/High

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Iwandavies351

Iwandavies351

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Has anyone ever tried to manipulate the Hi/Low switch to make the Disco think its in low at all times so that manual mode can be used when Hi is selected? if so, was it successful and also worth it?
 
Hi. The hi/low switch is in the transfer box so you can't "manipulate" it without selecting the gear unless you mean to trick the ECUs with a "low" input through an additional wire as the box to be in high while the ECUs to consider it in low which IMO is not a good ideea cos the engine will be overfuelled. FYI, both the engine and autobox ECUs are getting that input and the engine ECU has a more "agressive" fuel map for low gear so it's possible to get the M+S warnings too as the expected torque at certain rpms will be different than the mapped ones and the CAN will be mixed up... my advice is to not make such experiments unless you have an EGT gauge as to be able to back up if the temp is getting too high
 
Wondering why you feel the need for this?
The lever locks a range of gears so if you need engine braking, you have it, the "sport" button makes it a teeny tad more sporty, though I've used it a few times and cannot really tell the difference, to me the biggest pain is having to achieve speeds impossible on many roads to get lock up in top, but I have learned to live with it.
Speed limit on roads over 'ere is often 80 kph which makes it darn near impossible, or 90 kph if the mayor is a bit more reasonable but even then that is only just inside the lock-up limit. By the time you get lock-up you're often just coming up to the next roundabout. :rolleyes:
 
sierrafery said:
Hi. The hi/low switch is in the transfer box so you can't "manipulate" it without selecting the gear unless you mean to trick the ECUs with a "low" input through an additional wire as the box to be in high while the ECUs to consider it in low which IMO is not a good ideea cos the engine will be overfuelled. FYI, both the engine and autobox ECUs are getting that input and the engine ECU has a more "agressive" fuel map for low gear so it's possible to get the M+S warnings too as the expected torque at certain rpms will be different than the mapped ones and the CAN will be mixed up... my advice is to not make such experiments unless you have an EGT gauge as to be able to back up if the temp is getting too high
Click to expand...
Not sure on the overfuelling being an issue... tuning a diesel is normally about increasing fuel. And its not as if in low range a D2 belches clouds of black smoke.
 
Iwandavies351 said:
Has anyone ever tried to manipulate the Hi/Low switch to make the Disco think its in low at all times so that manual mode can be used when Hi is selected? if so, was it successful and also worth it?
Click to expand...
If you want manual control in High, then I believe there is a Compushift system or something you can retrofit to control the gearbox. Might be worth giving Ashcroft Transmission a shout. As I'm sure they have fitted things before.

Ultimately any electronically controlled gearbox can be made to do a lot of things with the right software.
 
Stanleysteamer said:
Wondering why you feel the need for this?
The lever locks a range of gears so if you need engine braking, you have it, the "sport" button makes it a teeny tad more sporty, though I've used it a few times and cannot really tell the difference, to me the biggest pain is having to achieve speeds impossible on many roads to get lock up in top, but I have learned to live with it.
Speed limit on roads over 'ere is often 80 kph which makes it darn near impossible, or 90 kph if the mayor is a bit more reasonable but even then that is only just inside the lock-up limit. By the time you get lock-up you're often just coming up to the next roundabout. :rolleyes:
Click to expand...
The reason is two fold. Firstly, i use the disco around my local town and barly reaches 30 to allow a change up to 3rd. Secondly, i also tow a horse box a lot around hilly roads, thus when going up hill, it kicks down out of lockup to 4th or even 3rd and revs its bo#%%ks off untill i reach a flat again. Thought this would give me some control over the kick down and able to select 3rd or 4th around town, keeping the revs down.
 
Iwandavies351 said:
thus when going up hill, it kicks down out of lockup to 4th or even 3rd and revs its bo#%%ks off untill i reach a flat again.
Click to expand...
If you are towing the size of tyres can make a huge difference so the question is what tyres do you have? If they are larger than standard fit std dimension tyres and it will be better eventually go for a remap rather than tricking the ECUs. I made this experiment on my manual to see how it behaves uphill and even though the climb was easyer with false low input the EGT went up to 850 and the ECT above 110 under load... that was the result of the overfuelling... i dont know how an auto would manage this, if you want to try on your own car i can tell you what to do but i insist to fit an EGT gauge, better a coolant gauge too before as to be on the safe side or you can end up with blown HG or hurt the turbo
 
Hi, i have 265, 70 R16 on her. Only one size bigger, no remap and she has plenty of power when she works for me, towing and off roading. also, the fuel economy is a bit s@#"t, I get about 19mpg at best, drops to 16mpg when towing. Would remaping sort that out as well? Any help or advise would be extremely greatfull.
 
The std dimension for D2 tyres is 235/70R16 or 255/65/16 so your's are more than 5% bigger which from my multiple tests is too much especially for an auto which uses the VSS for management big time, the fuel economy is the result of that too also the shift control is mixed up... i'm sure that the EGT is quite high too ... you'll have to tune it for your needs and those tyres or fit std tyres if you want it to behave as it was calibrated from factory... read this(and the link in it) https://www.landyzone.co.uk/land-rover/manual-tiptronic-gearbox.382278/post-5435358
 
I'm going to give a V8 gearbox ECU a try and will let you know hopw it gets on. as it was mentioned in another thread. finegrs crossed.
 
Iwandavies351 said:
The reason is two fold. Firstly, i use the disco around my local town and barly reaches 30 to allow a change up to 3rd. Secondly, i also tow a horse box a lot around hilly roads, thus when going up hill, it kicks down out of lockup to 4th or even 3rd and revs its bo#%%ks off untill i reach a flat again. Thought this would give me some control over the kick down and able to select 3rd or 4th around town, keeping the revs down.
Click to expand...
A kickdown inhibit would be handy. Pretty sure some Jeeps had that feature and in a modern vehicle with flappy paddles you'd probably be able to get it to hold a gear better too.
 
300bhp/ton said:
In other words, I do NOT believe it would be an issue at all.
Click to expand...
I dont want an unfriendly debate on this but IMO overfuelling is an big issue for any vehicle not just for the Td5 and as i said i've seen around 850*C EGT(even spikes to 900) and 120*C ECT on mine while it was overfuelled due to a false low input while it was in high so definitely an issue...unless you do believe that those high coolant and exhaust gas temps are OK
 
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