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IIRC - when driving in low range with MANUAL selected the auto trans will change DOWN but not UP - and you have got to be aware that when you are driving in M and you are on the brakes and coming to a stop, that you will stall the engine if you are not quick enough to nudge the shift lever into N… that suggests to me that the torque convertor is locked in any of the selected gears when with low range M selected.
I think it may only be fluid lockup that you are experiencing, that coupled with the gearing can make it seem like the converter is locked, the only way to tell would be looking at a nanocom or similar to see if solenoid 3 is on or not...Quote:
Originally Posted by RRT
I'm not 100% sure myself what happens, but I THINK it's only on decel it locks properly.
Cheers
James
Re ‘lockup’ RAVE maybe of help here - and on reflection I think that the auto trans actually changes Up but not Down when in low range manual - either way it’s been a while since I last got out to play☹️ due to the pandemic !!!Quote:
Originally Posted by shack
Unfortunately there seem to be a few errors in some of the official documents I have access too.Quote:
Originally Posted by onebob
But I have read everything I can get my hands on, fwiw manual mode operates a lot differently to normal low range.
Anyways my questions were merely for interest, as I said earlier, it works well as is.
Attachment 181259Quote:
Originally Posted by shack
Your are right re the lock up as to 0% throttle only in Manual mode.
Was interested to find though on page 54
P0722 * Torque converter slipping
Maintains current gear in low range, limp
home mode in high range. Shift pressure to
maximum, harsh gear shifts/engagement.
So I did not need to back off going up those dunes as I had been worried it would fault and go to third, as it will maintain gear ratio irrespective of the fault in M, arrrrgggghhhh.
Secondarily the trans goes to 3rd at stop but stays in fourth once moving with the P0722, again overtaking up the hill and getting Mario and Stan flashing me did not mean that I would have to drive in 3rd from then on, so stopped and reset it by restarting letting the cars and trucks I had just passed sail by, it stays in 4th, arrrrgggghhhh * 2.
For anyone following along and wondering what's going on, I've got 2 remapped TCU's out in the wild getting analysed and I'm waiting for feedback as to the improvement or lack thereof!
Looking forward to hearing the feedback.Quote:
Originally Posted by shack
DittoQuote:
Originally Posted by Rymnd
Hi All.
James was kind enough to send me one of his remapped TCU's for assessment.
This is on a TD5 Discovery with a V8 converter and VGT, full size intercooler, etc, running Shacks tune so I can only give a perspective from this at the moment.
I will also be testing on D2's with standard torque converters and turbos in the near future as I suspect the difference with a standard stall rate converter would be even more pronounced.
So bum dyno set to "S" for sensitive, Eco and Sport button pressed to "S" for Shacktuned and away we went.
The change from 1st to 2nd felt around 10% earlier than factory for a given throttle position on light application of the pedal, as were all the other changes.
This had been discussed earlier and suits my application with the VGT which, combined with the engine mapping, produces much more torque earlier in the range.
The earlier shift points combined with the V8 TC make for a much more relaxed torque wave of acceleration.
Full noise still allows maximum rpm shift points.
Also, for my application as I live in a rural area, so almost straight to either 90 or 110 kph depending which way I turn, James was able to reduce the time on the warm up strategy for TC lock up ( this suits me but not advisable for people in cold climates as the trans fluid does need to warm up quickly )
On to the icing on the cake, which is the lock up speed. On this revision, the lock up now happens at 75 kph in top and will drop back out of lock up at 75 with 0% throttle ( though even very slight throttle application will hold lock up down to the usual 1500 rpm ) This alone is a huge improvement.
Overall this has made the absolute most out of the 4HP22eh and this, combined with the "new school" engine mapping, gives a great, grunty, fun and enjoyable drive while ironing out the bugbears of the ZF4 box.
All the time and effort (and hexadecimal nightmares) well worth the end result.
Apologies if I have left anything out as this was written in the wee hours ( no interruptions :))
Thanks for that Discorevy.
I'll be interested to see what you think on the stock stuff as that's where I feel the most improvement will be.
Feel free to list any faults or strange behaviour you notice as this will be a benefit for everyone, including myself!
I don't want to be sending out TCU's that get returned because of erratic behaviour.
I haven't noticed any myself so that's good!