TopicToaster
SupporterI was one of the recent converts to the V8 TCU in a mapped TD5.
I had a spare V8 for parts lying around.. so in effect not much to lose.
When I fitted the TCU the difference was immediate when driving around town. The mapped TD5 had gobs of torque to easily haul itself at lower revs around town, and having it locked(usually in third) at up to about 70-ish was fuss free(ie. engine fuss) and just picked up nicely.
But the downside was almost undriveable at highway type driving. At 80k/h it was OK, but at 100-ish it would manically kickdown over the merest hint of a rise. Wayyy overkill.
I talked to Shack and he helped with some engine tune to calm it. Then almost perfect.
I think John points it out well here. I reckon the std TD5 converter is a bit too weak to hold properly at highway speeds.Originally Posted by johnp38
So the initial problem was the manic kickdowns(for seemingly no reason) that Shack tuned out .. then became more usable. But not that's done, the still no so ideal situation is that, still at highway speeds(say 90+) while it doesn't kick down so eagerly, you can feel torque converter slipping type issue. SO it's not quite unlocked, but there's a vibration and a could hundred more RPM from the engine that it should whilst the converter is locked(in 4th). Note that with the V8 TCU, 4 locked can be as low as 58k/h(that equates to about 1250RPM. I don't drive it that way. I always drive it half manually between 3rd and 4th .. and really only use 4th once up over 70+ and I know I'll be there for a good few klms or more.
3rd locked you see about 1720RPM at 60k/h .. and feels perfect. I measured 3rd locked at about 43k/h .. again feels fine(ie. not lugging).
+1 ... as said before it was Shack that sorted the manic over kickdowning issue.
So at a minimum, if you wanted to do this easy mod, if you don't feel comfortable to play with ECU mapping, I'd suggest it's best to have the TCU AND chat to Shack about getting the modded ECU modded again, to make it less sensitive to kickdown.
Ideally, do as John reckons too and look to a V8 converter upgrade too.
My TD5 is not actually mine(it's brothers), and I think that when the time comes to do it's transfer case and rear main seal jobs, almost certainly will plan to have torque converter V8 modded too.
Arthur.
All these discos are giving me a heart attack!
'99 D1 300Tdi Auto ( now sold :( )
'03 D2 Td5 Auto
'03 D2a Td5 Auto
ChatterBox
SupporterAk83...
I'd suggest that if you are "locked" and still experience flaring, then the converter is on the way out.
The tune you have (not mine) is not strong enough to cause converter slippage if the converter is healthy.
I'd be double checking pronto if it is flaring and get onto it if it is.
Cheers
James
TopicToaster
SupporterThanks mate, but the issue is the converter was rebuilt not long before(est. about 15K klms ago). Before your tune adjustment for the CC to work properly.. I put the TD5 TCU back in and worked fine. Only does it with the V8 TCU in.
Also done stall tests and seems to be OK according to RAVE @ about 2500RPM or so.
Arthur.
All these discos are giving me a heart attack!
'99 D1 300Tdi Auto ( now sold :( )
'03 D2 Td5 Auto
'03 D2a Td5 Auto
ChatterBox
SupporterNo worries..
YarnMaster
SupporterI tried an auto TCU from a V8 in my Td5. It was horrid, went back to the original. Shack has it now and I'm waiting to see what fancy auto mapping tuning he offers in the near future hopefully!
ChatterBox
SupporterI have the V8 TCU running fairly nicely back here in 2 vehicles.
Driveability is excellent.
I am however reluctant at this stage to recommend it as a no brainer fix to the stock setup.
I'm currently looking into what ak83 said as regards slippage, and that's taking some time, and also hard to quantify the reason for it.
And there are no publicly available map definitions for the Bosch TCU... At this stage.
If someone with a V8 and a nanocom wants to do me a log... That'd be handy!
Cheers
James
Fossicker
The responses / discussion have been very helpful, thanks all. I’m very much leaning towards biting the bullet and getting the V8 controller and work it out from there.
But to slightly hi-jack the discussion, anyone come across this before?
Auto Gearbox Tuner for Land Rover Discovery 2000 - 2004 2.5 TD5 - 138HP
ChatterBox
SupporterI haven't, others may have.
It's a little bit ambiguous though, and the fact it does so many vehicles is unusual.
I'm also not aware that the TCU on these vehicles can be reflashed in situ...
It may just be changing a couple engine ECU settings (hence the after 2001) and then resetting the Bosch TCU adaptions.
It would want to do something though for $450 au!!
Fossicker
Absolutely! I hear you. And the downsides are there’s no money-back guarantee and once flashed, one can’t write old config back with the tool. Too big a gamble, I reckon. Unless someone else has had success and can vouch for it…
YarnMaster
SupporterQuestion - why fit a V8 TCU and tune it to suit the Td5 rather than adjust the Td5 to suit better? Is it a case of the V8 one being tuneable and the Td5 one not? Or is the V8 a better/closer starting point?
If you want to get serious about this then the Compushift is the way to go but it's a lot of output and then still requires you to figure it all out and setup to suit - Jose of Td5Inside has previously described a wellsetup one in a D2 as being able to drive like it's a 6 speed transmission in it's effect - I've always been surprised that there isn't a tuning market for this like there is for the ECU's...
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