A340E lockup activation strategy

[Mos]

Hi,

I'm (slowly) working on a controller for the solenoids for the A340E auto transmission, to enable up/down control without touching the shifter.
My query relates to the activation of the torque converter lockup solenoid - what do people do in different uses?

Several initial thoughts are as follows:

Mode 1 - lockup only gets activated in 4th gear, de-activates as soon as the brakes are hit or a shift to 3rd is requested, or speed drops below a preset value. (Lockup activated by activating a shift to "5th" gear).

Mode 2 - lockup activated in any gear above 1st, de-activates for a 0.5-1s (?) on gear changes, deactivates if brakes hit or 1st gear selected or speed drops below a preset value.

Mode 3 - lockup always active above 1st gear, de-activates if brakes hit (is this commonly used for drags?).

Mode 4 - lockup always active above a certain speed (say 30km/h), deactivates if brakes hit.

Having not monitored the lockup when I had an auto, I'm not really sure when exactly it activates in factory situations.

Basically I'm after people's expectations/suggestions/advice on what a controller should do with the lockup.
One person (who I'm specifically making this controller for) wanted something along the lines of Mode 1.

Thoughts?

Mos.

[Sciflyer]

Service manual lists all the conditions for TC lockup/unlock, i'll see if i can dig out the page

Ive found with the A341E and a manual switch for the lockup (ie, no ECU control) it will not lockup at all in 1st or 2nd, also the solenoid should not be switched with the full 12vdc as its designed to operate normally via PWM

Changing between 3rd and 4th with it locked up is noticably jerkier but otherwise seems to be fine, however ive never tried it at WOT...

What im not sure of is whether this is different behaviour to the A340E or not

[Sciflyer]

excuse the bigness

This is the SC300 A340, on another page it also confirms there is no lockup in 1st and 2nd (and why would there be), yet some people are saying they can make it happen?

[JustenGT8]

Mode 1 would be the most practical i would have thought, especially for cars with any decent hp? I believe a WOT shift with the lockout engaged often = blown box?

[Dieseltrain]

JAK has been trialling Lockup from a standing start at the strip lately in his Cressida ... Havent heard any bad news yet ! Seems a bit lazier down low, whilst et's remain similar, the mph is up there, so im guessing you would only use the lockup once the rpms are up around peak torque figures anyway?

[Mos]

Ive found with the A341E and a manual switch for the lockup (ie, no ECU control) it will not lockup at all in 1st or 2nd, also the solenoid should not be switched with the full 12vdc as its designed to operate normally via PWM

What im not sure of is whether this is different behaviour to the A340E or not

Hmm interesting.
It can make sense to have hydraulic failsafes which only allow this solenoid to have an effect in certain gears - an A340E could be different in that way.
I wasn't aware of the PWM requirement for the A340E. The later boxes (whether that is A341E or not) have a two wire PWM lockup solenoid, rather than the single wire - is that what you're referring to or are you saying that the single wire ones are also or may also be PWM?

Changing between 3rd and 4th with it locked up is noticably jerkier but otherwise seems to be fine, however ive never tried it at WOT...

I believe a WOT shift with the lockout engaged often = blown box?

Well I guess it depends on how strong the clutches and lockup clutch are - assuming the lockup clutch doesn't slip, all the stress of the gearchange gets taken up by the clutches for that gearchange. I'm under no illusion that wear is not likely to significantly increase
The main reason for the suggestion was this:

JAK has been trialling Lockup from a standing start at the strip lately in his Cressida ... Havent heard any bad news yet !

I've heard rumours of people trying this in drag situations.
So while Mode 1 is definitely the go for a street application (maybe with a 3rd gear option), if it's not a significant complication a drag option can be implemented - just curious what's the most logical/useful way of implementing it.

Mos.

[web]

Check http://www.wjw.co.uk/Toyota/A340/22automati.pdf

Lists stock lockup schedule for A340E. Look at the 185R14 table, the one above that seems to have an error where lockup engages at a lower speed than it disengages, in PWR mode

I'd probably choose somewhere in between modes 2 and 3 myself. Engine braking is the thing I miss most when driving a granny-shift, manually shifted or not, so I'd work to keep that alive as much as possible, maybe even when braking, above a set speed. Not sure if releasing at, say, 1000rpm would be fast enough to prevent stalling when the brakes lock up, but I'd probably try it anyway.

I see nothing wrong with momentarily releasing lockup during shifting though - shouldn't make the car any slower, but is a lot easier on the box and drivetrain.

[131OWN]

Mos what a340 are you referring to as the valve body in the a340e found behind 1uz, 1jz, and 2jz are all different. They have between 3 and 5 solenoids depending what model you talking about, there are 2 solenoids that do determine what gear you are in and there is a lockup solenoid, but that is where the similarities end, for example on a340e found behind 2jzgte there are 2 other solenoids, these are used to control line pressure and accumulator pressure.

With regards to the converter lockup, 1uz a340e can only engage converter lockup 3rd and 4th gear, when a 1jzgte a340e can engage converter lockup in 2nd, 3rd, and 4th.

If you are considering in making these units for high performance cars, I would not set it up with buttons or paddles to change gears (leaving the shifter in drive) as there are a couple of other things that need to be bought to you attention, the a340e is at its strongest when you manually change the gears in conjunction with the correct shift solenoids sequence, this has to do with the operating mechanism for each gear as there are different clutches, brakes and one-way clutches engaged due to the positioning of manual valve in the valve body determined by the shifters position

Cam

[cambelt]

Id vote mode 1 , will it have speed and throttle inputs and or a pwr mode?
Back in 1985 when toyota first got the A340 , the auto had 3 modes , PWR, NORM and ECON . today it,s NORM and PWR.
In econ the trans did the full 7 shifts , 1st, 2nd, 2nd lock up, 3rd, 3rd lock up , 4th, 4th lock up .
In norm it did lock up in 3rd light throttle and 4th .
In pwr it was later shifts and lock up in 4th .
This was a stock MZ12 soarer ,I thought it must have been a sales pitch to have so many gear changes in econ but econ mode was to crazy to drive.
Dave

[Mos]

I'd probably choose somewhere in between modes 2 and 3 myself.

Okay "vote" taken

Engine braking is the thing I miss most when driving a granny-shift, manually shifted or not, so I'd work to keep that alive as much as possible, maybe even when braking, above a set speed.

The A340E only provides engine braking in L and 2, when selected mechanically. Electronically, it selects one way clutches rather than brakes, so it freewheels rather than providing engine braking - so unless you're shifting with the shifter it won't brake anyway.

Not sure if releasing at, say, 1000rpm would be fast enough to prevent stalling when the brakes lock up, but I'd probably try it anyway.

All the docs cut lockup when brakes are applied, so I'm not sure I'll be thinking about doing it differently (for now).

I see nothing wrong with momentarily releasing lockup during shifting though - shouldn't make the car any slower, but is a lot easier on the box and drivetrain.

I'm guessing it will make the shift marginally slower, but maybe made up by keeping the engine revs higher for slightly longer?

Mos what a340 are you referring to as the valve body in the a340e found behind 1uz, 1jz, and 2jz are all different. They have between 3 and 5 solenoids depending what model you talking about, there are 2 solenoids that do determine what gear you are in and there is a lockup solenoid, but that is where the similarities end, for example on a340e found behind 2jzgte there are 2 other solenoids, these are used to control line pressure and accumulator pressure.

I'm referring to the gearbox with 3 solenoids - usually called the A340E, though I'm not sure what you would call the 4 solenoid 1UZ box. I'm well aware of the 2JZ box (and a bunch of others with extra solenoids) but afaik that's designated as A341E rather than A340E.
Afaik MX83, JZX81, JZA70, JZX90 can be considered the "same" - ie 3 solenoids; things like JZX100, JZS147, etc have more.
In any case, I'm only considering boxes with 3 solenoids (for now), and possibly the 1UZ box with the fourth solenoid that (according to some installs) is "safe" to ignore and leave disconnected.

With regards to the converter lockup, 1uz a340e can only engage converter lockup 3rd and 4th gear, when a 1jzgte a340e can engage converter lockup in 2nd, 3rd, and 4th.

In your experience has it been all the 1JZ [3 solenoid] boxes?
It's becoming obvious there are a number of variations - if you could post which cars they came out of it wouldn't hurt.

If you are considering in making these units for high performance cars, I would not set it up with buttons or paddles to change gears (leaving the shifter in drive) as there are a couple of other things that need to be bought to you attention, the a340e is at its strongest when you manually change the gears in conjunction with the correct shift solenoids sequence, this has to do with the operating mechanism for each gear as there are different clutches, brakes and one-way clutches engaged due to the positioning of manual valve in the valve body determined by the shifters position

Ok, I hate you - just spent the better part of 4 hours looking through docs to support/dispute what you're saying ..
Anyway, the only stronger part is that when mechanically shifting in L and 2 (with appropriate electronic control) the hydraulics engage an additional brake in parallel with a one way clutch. This explains why the transmission freewheels when electronically controlled but provides engine braking in those shifter positions.
D (either 3rd or OD) has no distinction and is only electronically controlled, so there is no potential for increased strength.

So.. does this extra brake really help with transmission strength? I don't suppose people would've gone to the trouble of pulling a box apart to see what actually gave way. I'm quite curious about this

I can't post the pics at the moment, but there are tables and diagrams indicating which clutches/brakes/etc are engaged in various gears, showing this difference.

Id vote mode 1 , will it have speed and throttle inputs and or a pwr mode?

Actual automatic control is beyond the scope of this little project (at the moment). All shifts (other than maybe dropping out of lockup) will be user initiated.
The main idea behind this device is to enable people to run aftermarket ECUs with an auto, without the relatively, in my opinion, inelegant method of shifting gears with the shifter.
The victim requesting this device does not have a speed sensor fitted at the moment, so it's a complication both for me and him to implement
There are so many criteria for not entering certain modes, etc until certain conditions are met that the number of inputs required would increase the hardware beyond what's currently intended.
For the first version I was trying to figure out what to do with the lockup, but I appreciate all the additional information and discussion

I think the most sensible option for disconnecting lockup is brake input and IDL input - that should cover the bases for not stalling the engine when coming to the stop.

Back in 1985 when toyota first got the A340 , the auto had 3 modes , PWR, NORM and ECON . today it,s NORM and PWR.
In econ the trans did the full 7 shifts , 1st, 2nd, 2nd lock up, 3rd, 3rd lock up , 4th, 4th lock up .
In norm it did lock up in 3rd light throttle and 4th .
In pwr it was later shifts and lock up in 4th .
This was a stock MZ12 soarer ,I thought it must have been a sales pitch to have so many gear changes in econ but econ mode was to crazy to drive.
Dave

Funny you should mention that... some of the docs said in some 1990 cars they got rid of pattern select switches, and the transmission ECU determined the pattern from other inputs. In 1993 apparently they went to a single pattern in the ECU, and in 1999 they went back to pattern select switches - I guess the auto detection and single maps were determined to be insufficient
Apparently all the lockup saves is a 4-5% slip - no idea how that would translate to fuel economy (relative or absolute).

Mos.

[web]

All the things I said were based on the assumption that lockup = lockup... not a one-way deal. Without a chance of engine braking anyway, I'd choose mode 2 with no further mods.

Because I see no reason to leave lockup off in lower gears, or to leave it on during shifts. If you want faster shifts, IMO do it right and get a shift kit.

About the speed sensor : can the RPM signal replace that? After all, you know what gear it's in.

[1JZ.747]

i can see a lot of tranmissions getting blown and people pointing the finger at you mos, be very careful mate

i only ever used the lock up in 3rd gear on the dyno and at the track by giving the solenoid a direct 12 volts. Mike at MV has told me on numerous ocassions over the last 6 years, that they should only be locked in 3rd and overdrive gears and certainly not locked during gear changes.

hopefully when they blow up, they only burn out clutches and people dont have torque converters blast too pieces, ive seen this happen and people end up having it come through the floor of the car and flying into their legs and ending up in hospital getting pieces of converter taken out of their legs.

[131OWN]

Mos all "3 solenoids a340e," some tagged a3040le, a3041le, a3042le" that I have played with lock up in 2nd 3rd and 4th, these boxes I am refering to are found in jzz30, jzx90, jza70, jzx81 and ma70's. Found behind 1jzgte's and 7mgte's.
I have built around 20 control box which I have sold to many guys in SC and I also use in my car. My latest model has auto lock up in 3rd and 4th gears releasing for 1sec during that gear change. This works the best.

In my car which is making around 500rwhp, when you lockup converter in 2nd gear at WOT is shutters the converter, I would say this has to to do the power it is making, as It doesn't occur in less HP applications.

[stevevp]

Mos, the follwing may help a bit too http://www.reanimotion.com/ToyMods/a...0automatic.htm
I would say mode1 but third and fourth gear

As for engine braking - remember the cruise control overrides the idle switch cut out by driving the lock up signal in the ecu to enable hill deceleration, so engine braking is certainly possible in drive


also if you are interested in the A351 5 speed strategy
http://www.reanimotion.com/ToyMods/a...0automatic.htm

[PlacentaJuan]

i am having trouble with the different variants of this transmission.

from what i am aware 2 big differrences beweeen the old (7mge/gte and vvti 1j series) auto and new (2jz and 1jzvvti) auto are: mechanical throttle cable vs / tps

and

i am told (from mv autos) that the 2jz box has an extra set of planetary gears that makes it stronger.

i have the a340e manual for 7mge/gte (and i assume the non-vvti 1jz) can someone please link me this box for the 2jz.