Hi everyone
I have a '94 Terrano TD27T with auto trans. I want to do some playing around with the electronic auto trans controller, as I don't like the way it controls it as stock.
First, and most important step, is to actually find it! So does anyone know where it is?
Auto trans ECU modifications on WD21 terrano?
Moderator: Mark
Auto trans ECU modifications on WD21 terrano?
Last edited by stumo on Mon Jan 29, 2007 10:29 pm, edited 1 time in total.
In an odd spot, behind the speaker box and interior panel on the left hand side of the boot/tray area.
Have a look in the tech section, i posted a article on controling the high gear lock up clutch that works well
I didn't like the way mine worked either, and tried to play with it but didn't get far. I tried computer out of a V6 as an experiment but no imrovement
Have a look in the tech section, i posted a article on controling the high gear lock up clutch that works well
I didn't like the way mine worked either, and tried to play with it but didn't get far. I tried computer out of a V6 as an experiment but no imrovement
lax2wlg wrote:Is that like saying 'she's hot, for a crackwhore??
Thanks DieselBoy.
Umm, mine must be different to yours because my rear speakers are in the roof pointing down into the boot area (its a 5 door).
I had a look behind the passenger side interior panel of the boot area just below the rear side window and I found 3 things...
1. the rear wiper controller
2. the glow plug controller
3. an ECU with a "E8" label on it.
I thought the "E8" box would be it, but when I unplugged it, the check light for the AT (the light in the power/normal/hold switch) still flashed its AT fault codes to me. To me that suggests the "E8" box is not the AT ECU
On a short test drive with it unplugged, only the rev counter was not working, engine and trans seemed to be working normally 
So do you have any more ideas?
I saw your great article about the torque convertor lock soenoid, and I plan to do it as an initial quick fix.
I write software for a small ECU company, so ideally I'd like to swap out the stock AT ECU with one of ours, and write some custom tunable code for it. But I need to see the current one to work out the I/O and hence the potential control options to see if it is worth doing. Would be awesome to have a tiptronic mode aay.
Cheers
Umm, mine must be different to yours because my rear speakers are in the roof pointing down into the boot area (its a 5 door).
I had a look behind the passenger side interior panel of the boot area just below the rear side window and I found 3 things...
1. the rear wiper controller
2. the glow plug controller
3. an ECU with a "E8" label on it.
I thought the "E8" box would be it, but when I unplugged it, the check light for the AT (the light in the power/normal/hold switch) still flashed its AT fault codes to me. To me that suggests the "E8" box is not the AT ECU
On a short test drive with it unplugged, only the rev counter was not working, engine and trans seemed to be working normally
So do you have any more ideas?
I saw your great article about the torque convertor lock soenoid, and I plan to do it as an initial quick fix.
I write software for a small ECU company, so ideally I'd like to swap out the stock AT ECU with one of ours, and write some custom tunable code for it. But I need to see the current one to work out the I/O and hence the potential control options to see if it is worth doing. Would be awesome to have a tiptronic mode aay.
Cheers
There are also some devices on the opposite side of the boot as well, not sure what tho. Was told that the radio power amp is in there, but I diddnt see it when I changed my sound system. I also have the speakers in the roof, and as a side note, if you want to change them look out. They are 5x7 so a 6x9 will need a spacer to drop it down a little. I custom made mine and it looks sweet.
Will be watching this space to see how you get on.
Have you looked at interfacing the system to a PC yet for diagnostics? I looked at this but found the plug (under the fuse box) is too old.
Will be watching this space to see how you get on.
Have you looked at interfacing the system to a PC yet for diagnostics? I looked at this but found the plug (under the fuse box) is too old.
Ok people, move along. Nothing to see here. Thank you, move along.
Ph 0212078472
Ph 0212078472
Okay kiwipete, I will have a look there when I get a chance.
I did a bit of trawling on 'tinternet and found some free factory service manuals for US Pathfinders here...
http://www.phatg20.net/modules.php?name=Downloads&d_op=viewdownload&cid=76
The auto trans section of the FSM has kind of put me off a bit, as the ECU controls a hell of a lot of clutches and solenoids within the tranny itself, which have to be controlled in certain sequences at specific TPS and RPM etc etc. It can be done, but it would take a long time to write my own code to do that, plus I don't want to blow up my tranny if I get something wrong.
The main problems I have with the stock auto shift are...
1. In "Hold" mode (which is the only really usable mode for the TD27), it never selects 1st gear. So you will be sitting at the lights on a steep hill, then it struggles to pull away in 2nd becasue it never selects 1st.
2. The 4th gear (which is actually unlocked overdrive) is never really held by the controller, so when you hit a hill at highway speed in 5th (locked overdrive), it will struggle up the hill until revs fall below 2000, then will change into "4th" for about half a second, before changing to 3rd whereby revs are about 3000. In the TD27 3000 is way beyond the useful torque curve for the engine (not to mention noise and vibration levels), so you actually start to decelerate even more (unless your engine and fuel system is in peak condition) This is really irritating when trying to overtake - you basically have to ring the nuts off the engine to get past - assuming your fuel system is up to it - otherwise you get passed!
I believe the 4th gear problem can mostly be solved by dieselBoy's mod. And the 1st gear problem can be solved by using some discrete electronic components wired up to the vehicle speed signal and the A/T mode switch. So that when speed is zero, it selects normal mode, then when speed increases it switches back to Hold mode.
I will get around to it "one of these days(TM)"
Cheers.
I did a bit of trawling on 'tinternet and found some free factory service manuals for US Pathfinders here...
http://www.phatg20.net/modules.php?name=Downloads&d_op=viewdownload&cid=76
The auto trans section of the FSM has kind of put me off a bit, as the ECU controls a hell of a lot of clutches and solenoids within the tranny itself, which have to be controlled in certain sequences at specific TPS and RPM etc etc. It can be done, but it would take a long time to write my own code to do that, plus I don't want to blow up my tranny if I get something wrong.
The main problems I have with the stock auto shift are...
1. In "Hold" mode (which is the only really usable mode for the TD27), it never selects 1st gear. So you will be sitting at the lights on a steep hill, then it struggles to pull away in 2nd becasue it never selects 1st.
2. The 4th gear (which is actually unlocked overdrive) is never really held by the controller, so when you hit a hill at highway speed in 5th (locked overdrive), it will struggle up the hill until revs fall below 2000, then will change into "4th" for about half a second, before changing to 3rd whereby revs are about 3000. In the TD27 3000 is way beyond the useful torque curve for the engine (not to mention noise and vibration levels), so you actually start to decelerate even more (unless your engine and fuel system is in peak condition) This is really irritating when trying to overtake - you basically have to ring the nuts off the engine to get past - assuming your fuel system is up to it - otherwise you get passed!
I believe the 4th gear problem can mostly be solved by dieselBoy's mod. And the 1st gear problem can be solved by using some discrete electronic components wired up to the vehicle speed signal and the A/T mode switch. So that when speed is zero, it selects normal mode, then when speed increases it switches back to Hold mode.
I will get around to it "one of these days(TM)"
Cheers.
Here is something that may interest you, or it may not..........
http://translate.google.com/translate?sourceid=navclient&hl=en&u=http%3a%2f%2fwww%2egeocities%2ejp%2fkeng%5fs%2findex%2ehtml
http://translate.google.com/translate?sourceid=navclient&hl=en&u=http%3a%2f%2fwww%2egeocities%2ejp%2fkeng%5fs%2findex%2ehtml
Ok people, move along. Nothing to see here. Thank you, move along.
Ph 0212078472
Ph 0212078472
Okay, I have done some mods now, so just to report back on my findings...
The TCU (Tranny Control Unit) is on the drivers side of the boot area (mine also had an amp for the stereo in there too).
I did DieselBoys excellent lock up solenoid mod, which is a prerequisite for my next mod.
What I did was to trick the TCU into thinking I never go above half throttle. This means it upshifts earlier and holds gears for much longer before downshifting. Accelerating is pretty similar to the stock "hold" mode (even when in power and A/T modes). The real benefit is not having it change down at the slightest increase in TPS like it used to. So you avoid the down/up/down/up/down flapping around with the throttle that it used to do.
So from a standing start in A/T or power mode, I now get first gear
, then upshifts at full throttle occur at around 2300 for each gear up until 4th (unlocked overdrive). Then 5th (locked overdrive) occurs just over 65km/h at full throttle giving about 1700rpm, this is why the lock mod needs to be done, since trying to accelerate onto the motorway at 65kmh/1700rpm would take a while. Or you could just use the stick and o/d button and ring the nuts off it like it used to do anyway!
Round town driving at full/part throttle it is so much better now, it changes quickly up through the gears into 4th, and it stays there regardless of throttle. It will change down only when speed drops. This suits my driving style perfectly, but would not suit everyone, and is only really suitable on the TD27T.
The other downside is that I have disabled the kickdown switch. I could re-enable it and use a relay to bypass my TPS mod during kickdown, but at the moment I cannot risk enabling it and the TCU re-calibrating itself for full throttle - cancelling out my mod. I always used to use the hold mode, which seems to ignore kickdown anyway!
What I did was cut the TPS sensor wire to the TCU, and insert a resistor and 2 diodes into the curcuit and reconnect to the TCU. The TPS normally goes from 1.5v at closed throttle, to 4v at full throttle. With my mod, the TCU sees the throttle normally, up until about 2.2v (about 50% throttle) where it clips and stays at 2.2v ragardless, until TPS drops back down again. By using different diodes, you could tune the clipping point to suit your driving style.
Thanks for all the help DieselBoy and kiwipete.
Cheers
The TCU (Tranny Control Unit) is on the drivers side of the boot area (mine also had an amp for the stereo in there too).
I did DieselBoys excellent lock up solenoid mod, which is a prerequisite for my next mod.
What I did was to trick the TCU into thinking I never go above half throttle. This means it upshifts earlier and holds gears for much longer before downshifting. Accelerating is pretty similar to the stock "hold" mode (even when in power and A/T modes). The real benefit is not having it change down at the slightest increase in TPS like it used to. So you avoid the down/up/down/up/down flapping around with the throttle that it used to do.
So from a standing start in A/T or power mode, I now get first gear
, then upshifts at full throttle occur at around 2300 for each gear up until 4th (unlocked overdrive). Then 5th (locked overdrive) occurs just over 65km/h at full throttle giving about 1700rpm, this is why the lock mod needs to be done, since trying to accelerate onto the motorway at 65kmh/1700rpm would take a while. Or you could just use the stick and o/d button and ring the nuts off it like it used to do anyway!
Round town driving at full/part throttle it is so much better now, it changes quickly up through the gears into 4th, and it stays there regardless of throttle. It will change down only when speed drops. This suits my driving style perfectly, but would not suit everyone, and is only really suitable on the TD27T.
The other downside is that I have disabled the kickdown switch. I could re-enable it and use a relay to bypass my TPS mod during kickdown, but at the moment I cannot risk enabling it and the TCU re-calibrating itself for full throttle - cancelling out my mod. I always used to use the hold mode, which seems to ignore kickdown anyway!
What I did was cut the TPS sensor wire to the TCU, and insert a resistor and 2 diodes into the curcuit and reconnect to the TCU. The TPS normally goes from 1.5v at closed throttle, to 4v at full throttle. With my mod, the TCU sees the throttle normally, up until about 2.2v (about 50% throttle) where it clips and stays at 2.2v ragardless, until TPS drops back down again. By using different diodes, you could tune the clipping point to suit your driving style.
Thanks for all the help DieselBoy and kiwipete.
Cheers
Another update, since I have been using this mod for a while now.
The TPS mod I did is still really good, I tweaked it a little bit to give me slightly higher revs on upshifts.
The main thing I have done now is to give the tranny a new gear. This new gear is slightly lower ratio than 4th (unlock overdrive). You see I found that if you cut power to the TCU, the tranny goes into limp-home mode, which is 3rd gear. So what I did was rig up a momentary double pole switch, so that when pressed, power is cut to the TCU, and routed to the torque converter lock solenoid. So my new gear is locked 3rd.
I found that using dieselBoys unlocked overdrive mod, that the climbing/passing performance of the wagon in that gear was still a bit crap. I think this is due to the highly overdriven ratio that is used for the overdrive - it basically just causes more heat to be produced in the torque converter. Maybe this is why the stock TCU never holds that gear for more than a few seconds when changing down. Sure enough, when I climb my test hill in unlocked overdrive, the speed dies down quite quickly from 3000@100km/k right down to 2400@80km/h. Then when I activate my new gear (halfway up this big hill) revs go from 2600 at 80km/h and it acelerates back up to 3200@100km/h.
So this gear is much more efficient, and avoids the losing of locked overdrive (until reset) that occurs with db's mod. Which will occur if you have solenoid lock switched off, and the TCU tries to engage it and obviously fails, it will never try again until you power cycle.
As ever, there are a couple of drawbacks...
1. in limp-home mode there is no overrun clutch - so it is like selecting neutral on overrun. Not a problem for me since I have it on a momentary switch and only use it for climbing/passing.
2. when the switch is released, the tranny stays in unlocked 3rd for about 1 second, while it boots up. This increases revs by about 500 at 100km/h for that 1 second before the TCU selects locked OD.
I'm calling this mod - "push to pass" which is used in some racecar ECU's to provide a short burst of power for passing etc.
Cheers.
The TPS mod I did is still really good, I tweaked it a little bit to give me slightly higher revs on upshifts.
The main thing I have done now is to give the tranny a new gear. This new gear is slightly lower ratio than 4th (unlock overdrive). You see I found that if you cut power to the TCU, the tranny goes into limp-home mode, which is 3rd gear. So what I did was rig up a momentary double pole switch, so that when pressed, power is cut to the TCU, and routed to the torque converter lock solenoid. So my new gear is locked 3rd.
I found that using dieselBoys unlocked overdrive mod, that the climbing/passing performance of the wagon in that gear was still a bit crap. I think this is due to the highly overdriven ratio that is used for the overdrive - it basically just causes more heat to be produced in the torque converter. Maybe this is why the stock TCU never holds that gear for more than a few seconds when changing down. Sure enough, when I climb my test hill in unlocked overdrive, the speed dies down quite quickly from 3000@100km/k right down to 2400@80km/h. Then when I activate my new gear (halfway up this big hill) revs go from 2600 at 80km/h and it acelerates back up to 3200@100km/h.
So this gear is much more efficient, and avoids the losing of locked overdrive (until reset) that occurs with db's mod. Which will occur if you have solenoid lock switched off, and the TCU tries to engage it and obviously fails, it will never try again until you power cycle.
As ever, there are a couple of drawbacks...
1. in limp-home mode there is no overrun clutch - so it is like selecting neutral on overrun. Not a problem for me since I have it on a momentary switch and only use it for climbing/passing.
2. when the switch is released, the tranny stays in unlocked 3rd for about 1 second, while it boots up. This increases revs by about 500 at 100km/h for that 1 second before the TCU selects locked OD.
I'm calling this mod - "push to pass" which is used in some racecar ECU's to provide a short burst of power for passing etc.
Cheers.