700R4 with boost pros and cons (pressure vs TPS)
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Engine: 3xx ci tubo
Transmission: 4L60E & 4L80E
700R4 with boost pros and cons (pressure vs TPS)
This is a continuation of the hi-jacked thread:
https://www.thirdgen.org/forums/powe...bo-87-a-2.html
I agree that it is a solution to the problem but the ECM still requires a code change to make the line pressure vs TPS and MAP. Stock is just TPS (from memory).
A custom unit could be built for the trans controller, but with the truck ECM already available it is a cheaper, easier, already tested solution. Yes, they are making a good margin. A box would consist of the processor (I like the RISC AVRs), a few inputs (TPS, DRP, MAP, VSS), an PWM driver for the force motor, maybe for TCC if people wanted it, and the solenoid inputs and outputs. Overall, less than 50-$100 to build.
I don't see why anyone would buy one when the Chevy ECM is under $100
Yes, here is the thread. Sorry for hi-jacking your build thread. Yes, even with the Chevy ECM there is a problem. The trans code needs changes to make it pressure vs TPS and MAP. Not just TPS like it is. I have the capability to change the code and test it on my work bench so I will make the changes before I put it in the vehicle. These things take a while to test out though.
I am not impressed with the aftermarket controllers especially when a GM stock ECM can do it for under $100.
Not that I have seen.
I like that response. At least she is listening. I try that with mine but her eyes just start to glaze over as the boredom sets in. Now, when I head to the garage I just say I am going to measure something.........because she knows what a tape measure is and can understand that.
I haven't looked at the 700R4 hyd ckts in a long time. I don't remember, but I would think a good trans guy would be able to make one of these work. Really though, this trans has been out for 20+ years and there isn't a solution to this problem already? There must be and I am just ignorant of knowing it is out there.
It would work.
https://www.thirdgen.org/forums/powe...bo-87-a-2.html
I don't really see it being an issue unless the ECUs have an impedance that significantly changes the voltages. I don't really think dual ECUs are any worse than a controller/ECU pair though either. At the same time it may be easier to start from scratch in a lot of ways and build something with a Pic, AVR or Motorola CPU and call it a day. Definitely would be cheaper than a prebuilt controller whoever is making those and selling em is making very good margin indeed.
A custom unit could be built for the trans controller, but with the truck ECM already available it is a cheaper, easier, already tested solution. Yes, they are making a good margin. A box would consist of the processor (I like the RISC AVRs), a few inputs (TPS, DRP, MAP, VSS), an PWM driver for the force motor, maybe for TCC if people wanted it, and the solenoid inputs and outputs. Overall, less than 50-$100 to build.
I don't see why anyone would buy one when the Chevy ECM is under $100
This subject deserves its own thread! I've never actually put much thought into the issue of part throttle boost vs part throttle line pressure before reading these posts. The problem isn't really resolved by going electronic either, as the aftermarket solutions I've been research all rely on "Line Pressure vs TPS" tables and none seem to offer any kind of MAP based modifier or table. What did you expect for $500 to $800? 
I am not impressed with the aftermarket controllers especially when a GM stock ECM can do it for under $100.
I was just commenting to my wife (on deaf ears I'm sure!) that the old TH350 modulator valve design is actually superior in some ways to TVS for boosted applications. She said then drill a %@# hole and put a modulator on the side of the 700R4 to make yourself feel better. It's nice to have an understanding wife. 
Seriously though, I wish I could remember how the line pressure circuit was laid out in the 700 when I did the shift improver kit. It seems someone could figure out a way of modulating the line pressure using a boost reference that could override the line pressure setting of the TVS. Perhaps put an FMU on the main pump with a boost reference LOL
Seriously though, I wish I could remember how the line pressure circuit was laid out in the 700 when I did the shift improver kit. It seems someone could figure out a way of modulating the line pressure using a boost reference that could override the line pressure setting of the TVS. Perhaps put an FMU on the main pump with a boost reference LOLI haven't looked at the 700R4 hyd ckts in a long time. I don't remember, but I would think a good trans guy would be able to make one of these work. Really though, this trans has been out for 20+ years and there isn't a solution to this problem already? There must be and I am just ignorant of knowing it is out there.
It would work.
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From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: 700R4 with boost pros and cons (pressure vs TPS)
My wife isn't particularly interested but I have her do most of my tuning while I'm doing the driving. It's always entertaining to put her in the driver seat though.. I don't know what she's gonna do when my car actually gets fast as 10 psi was more than enough for her. Wait till she makes her first 7 second 1/8 mile pass!
I would think a megasquirt box could handle the task of running a 4L60e if someone knew their programming. Count me out of hard core coding like that. I can write some scripts but that is about all. On that subject, there is local guy that is just a complete genius and he is heavily involved with MS2Extra developement. I need to get in touch with him anyway because I'm supposed to test out a bluetooth programmer he's developing for the MS. He stays extremely busy in work related projects but if anyone could make such a device to control the E transmissions it is him.
Something else I've been wondering about is how the governor in the 700R4 works. It is an RPM actuated valve mechanism. As the weights swing out, the valve gets pushed further and further. I still haven't quite figured out how it all works while in drive, but the point is the governor controls the shift points. As the line pressure is brought up by the TVS cable position, I'm assuming more force is put against the valve and thus the RPM has to be higher to get the shift to occur. Now my idea is to replace this weight mechanism with a servo. The servo would be driven by a stand alone computer that would move to whatever position you program for a given condition (rpm vs tps vs map vs mph). I believe line pressure would have no effect on the shift point in this configuration as the servo will ignore resistance and push through to the desired position. Line pressure itself would be controlled by a separate servo and would be programmable based on the same parameters. This means you could have high line pressure before you even build boost if you floor it... or line pressure will come up as you begin to lose vacuum during part throttle acceleration. You could have full line pressure by the time you reach 4 inches of vacuum for example.
Disclaimer: I don't know much about the inner workings of the 700r4 and my above thinking could be quite flawed!
I would think a megasquirt box could handle the task of running a 4L60e if someone knew their programming. Count me out of hard core coding like that. I can write some scripts but that is about all. On that subject, there is local guy that is just a complete genius and he is heavily involved with MS2Extra developement. I need to get in touch with him anyway because I'm supposed to test out a bluetooth programmer he's developing for the MS. He stays extremely busy in work related projects but if anyone could make such a device to control the E transmissions it is him.
Something else I've been wondering about is how the governor in the 700R4 works. It is an RPM actuated valve mechanism. As the weights swing out, the valve gets pushed further and further. I still haven't quite figured out how it all works while in drive, but the point is the governor controls the shift points. As the line pressure is brought up by the TVS cable position, I'm assuming more force is put against the valve and thus the RPM has to be higher to get the shift to occur. Now my idea is to replace this weight mechanism with a servo. The servo would be driven by a stand alone computer that would move to whatever position you program for a given condition (rpm vs tps vs map vs mph). I believe line pressure would have no effect on the shift point in this configuration as the servo will ignore resistance and push through to the desired position. Line pressure itself would be controlled by a separate servo and would be programmable based on the same parameters. This means you could have high line pressure before you even build boost if you floor it... or line pressure will come up as you begin to lose vacuum during part throttle acceleration. You could have full line pressure by the time you reach 4 inches of vacuum for example.
Disclaimer: I don't know much about the inner workings of the 700r4 and my above thinking could be quite flawed!
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