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  #691  
Old 04-15-2008, 05:48 PM
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Quote:
Originally Posted by Trevor View Post
Phil, sincere apologies.

In the past I have always used “FWD” as meaning Four Wheel Drive, which in this instance has lead to what amounts to an error. Please read as follows:-

When the normally closed solenoid is energised via a high duty cycle the valve will open and control pressure will be bled off. Reduced pressure will result in the clutch opening and therefore no Four Wheel Drive, i.e. only Front Wheel Drive.

Again sorry for the confusion. Trevor.
OK Trev. That explains it. No need to apologise. It looks like we are all understanding it the same way now.
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  #692  
Old 04-15-2008, 06:30 PM
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Quote:
Originally Posted by oab_au View Post
Phil you can't have a Duty cycle of 0% or 100%, or it is not a Duty cycle it is DC. It is usually quoted as 5% to 95%.

Harvey.
A very low duty cycle can in fact result in a virtual fully open or closed valve depending on configuration, without the signal appearing as absolute D.C. The solenoid armature and valve components have weight, and friction also exists, both affecting electrical efficiency. Therefore a time constant is involved in respect of the onset of reciprocal movement.
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  #693  
Old 04-16-2008, 12:34 AM
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Quote:
Originally Posted by b3lha View Post
Good thinking. I hope it is a linear relationship, but LAN said in another thread that it is not.

If it is a linear relationship I have a doubt about your maths. Or maybe mine. It's late (here) and one or both of us is wrong.

Your x coefficient "5/9" is positive therefore your graph will slope upwards.

But I think it should slope downwards, from (0,50) to (95,0). So the coefficient should be negative. By my reckoning the equation would be y=(-5/9)x + (475/9). Your x=65 would give y=17, therefore 83:17 torque split.

Or, if the known points are actually (0,50) and (100,0) [which makes more sense, 100% duty = FWD] it becomes easier y=(-1/2)x + 50. Then x=65 gives y=18, therefore 82:18 torque split.
Sorry! You're right, I was just really tired. I re-did the math by hand at work and got the same equation you did, with the same results. I feel embarrassed.
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  #694  
Old 04-18-2008, 03:03 AM
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Just confirmed that with the FWD fuse in place, Solenoid C reports 95%.
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  #695  
Old 04-18-2008, 05:37 PM
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Quote:
Originally Posted by Nomake Wan View Post
Just confirmed that with the FWD fuse in place, Solenoid C reports 95%.
The above exactly confirms what I stated and detailed in a write up a very long time ago. The write up was argued against in a vindictive manner from a single quarter. Although proven wrong, no correction or apology has been forthcoming.
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  #696  
Old 04-22-2008, 08:00 PM
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Quote:
Originally Posted by Nomake Wan View Post
Okay, just went on another run. Unfortunately, during this run my wiring to the TCU for POWER mode seems to have fallen apart (though I've checked it and it seems to be correct, so I'm not sure why it isn't registering power mode anymore). I'll have to redo it tomorrow, but until then, it's back to normal USDM economy mode...

Anyway, some observations from this run.

1.) Those weird secondary percentage indicators appear on all three of the Duty Solenoids. Bug in the GUI.

2.) Duty Solenoid B remains at 5% when unlocked. When the torque converter locks, the solenoid jumps to 50% and then transitions from 50% to 95% gradually. If the transmission is in "Normal" mode when you disengage the cruise control, it drops to 55%, but does not go down to 5%. So when driving around without Power Mode, the torque converter appears to be in a semi-locked state. Odd. It'll go down to 5% if you start to brake for a stop, though. Presumably to prepare for sudden acceleration.

Hope this helps some!

Been thinking about the way the B solenoid drops to 55% duty cycle, instead of either on or off.

I think that the lock-up clutch is applied all the time and is not released for gear changes. It just drops the pressure applied to the clutch, so that if there is any sudden change in load during the gear change, the clutch will slip to prevent any shock being felt.

Harvey.
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  #697  
Old 04-22-2008, 09:11 PM
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Nomake,

Solenoid valve B is controlled by the TCU such that when lock up is called for, the valve is initially only half engaged, to be gradually increased so as to achieve a smooth take up.
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  #698  
Old 04-23-2008, 12:58 AM
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I figured that, Trevor. However, what I didn't understand is why cruising around, it stays at half-engaged instead of going to fully-disengaged.
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  #699  
Old 04-23-2008, 06:32 AM
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Quote:
Originally Posted by Nomake Wan View Post
I figured that, Trevor. However, what I didn't understand is why cruising around, it stays at half-engaged instead of going to fully-disengaged.
Nomak,

Solenoid valve “B” is normally closed and energised to open. When at a duty ratio of 95% the valve is opened to drain and no lock up duty pressure is available. As a result the lock up control valve, through a pressure differential arrangement, causes lock up.

This set up is possibly the reverse of what you may have assumed, but the end result is as you will have expected. The pressure differential arrangement assists with smooth partial engagement when SV “B” is part open, say 50%.

You have advised, --- ”If the transmission is in "Normal" mode when you disengage the cruise control, it drops to 55%, but does not go down to 5%. So when driving around without Power Mode, the torque converter appears to be in a semi-locked state."

SV “B” is under direct control from the TCU and vehicle speed, engine speed and the selector signal are all involved in the control of lock up. Therefore a signal could be present which you have not taken into account and further observation may provide a clue. Unfortunately there is no evidence within the available data which otherwise explains your findings.
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  #700  
Old 04-26-2008, 06:05 PM
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Updated version of the tcuscan software. Some extra features and hopefully a few bugs fixed.

It's a bit slow because of all the values it's reading. I think that is why the original select monitor only displays one value at a time.

EDIT: Updated again with some more features and bug fixes. It still looks like a GCSE CompSci project from the 1980's.
Attached Files
File Type: zip new.zip (51.2 KB, 395 views)
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Last edited by b3lha; 04-29-2008 at 05:09 PM.
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  #701  
Old 05-02-2008, 02:15 PM
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Cool Progress

Yesterday was an epic day for this project. I made two major steps forward.

Firstly, I have successfully reprogrammed a TCU and it's quite easy to do:

You have to remove the existing ROM chip, then solder a socket onto the board in the space provided, then program the new eprom and put it in the socket. A Picture speaks 1000 words (but takes up more disk space):



To remove the ROM chip, heat each of it's legs one at a time with the soldering iron and slide a knife blade underneath to separate it from the board. Finish one side first then the other.



That choking noise you can hear is Joe having a fit because he's just realised that it is HIS TCU that I am experimenting on, with no guarantee that it will ever work again.

After removing the chip it is necessary to clean up any remnant solder around where the chip used to be to avoid shorting anything.



The next step is to clean out the holes where you are going to install the socket. This is a time-consuming process which involves repeatedly burning oneself with the soldering iron. The best method I found was to hold the board vertically, put the soldering iron on one side of each hole and the solder sucker (spring-loaded syringe) on the other side. When the solder melts you fire the solder sucker and it sucks the liquid solder out of the hole.

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Last edited by b3lha; 05-02-2008 at 02:17 PM.
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  #702  
Old 05-02-2008, 02:15 PM
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Having done that it takes just a moment or two to solder the socket in place



Then it's time to program the new chip. I am using an SST 27SF512 eeprom chip supplied by Calum and a cheap chinese Top2004 programmer from ebay. The data I am writing to it is a UK TCU image that I have modified so the economy switch will engage power mode instead. After writing the chip I read it back and verified it against the image file to ensure it had been written successfully.



Here is the modified TCU with the eeprom installed.



Then I took it out and plugged it into the car to check that it worked. And it did!!!! I used the select monitor adapter to connect to the TCU and download the part of the program that I had altered, and it matched perfectly. The very fact I was able to connect proves that the device is working. So hardware side of modifying the TCU is now possible.

However, there seems to be a bug in my software changes. The power mode is stuck on permanently. So I have to do some debugging and re-burn the eprom. But that shouldn't be too hard to do.

Phil.
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  #703  
Old 05-02-2008, 02:23 PM
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Very cool Phil, The first time I opened a TCU case, I knew it would be as simple as loading a socket and writing the new eprom... Just don't have the level of commitment or expertise you do... Good work!!

Tom
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  #704  
Old 05-02-2008, 02:32 PM
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Secondly, I have managed to modify the ECU. Remember the printed circuit boards I had made up?



I was having trouble finding the components to go on them, but Calum was able to source them for me. Thanks again Calum.

The first step was to fit a socket onto the motherboard of my ECU. Most SVXes already have a socket, but my JDM ones don't.



The procedure is exactly the same as described in the TCU mod above. Clean out the holes and solder in the socket. I also removed the tan resistor that activates external memory.



Then I started to build one of the boards



First I soldered the components to the top side



Then I fitted the pin lines on the underside that plug into the socket on the ECU.



Then it's just a case of writing the eeproms and plugging it in.



I went out to the car, plugged it in and it works perfectly. As before I used the select monitor adapter to download part of the modified program and compare to my original file.

How much more horsepower do I have? None. Yet. My black 92 is now running the JDM 94 program with the 180km/h speed limiter code removed. I'll reprogram the eeproms as and when we come up with some useful mods.

Phil.
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  #705  
Old 05-02-2008, 03:39 PM
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Phil,

You are most certainly one who deserves an STI gong.

Trevor.
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