[Diy_efi] Using GM '747 to control TCC lockup only -- THANKS!

[David M. Ingebretsen]

Many, Many, thanks to all who helped. 

When I had the transmission built, I had the guy put in a "kit" so that I
have a self grounding solenoid in it already. It is also wired so I can have
it engage in 2nd through overdrive or only in overdrive. I had to do some
fancy wiring to get it to work with the 747 ECU. 

I think the ideas that use a vacuum switch get me most of the way there. I
found that B&M makes a speed dependent lockup, and I think a combination of
that with a vacuum switch might be close enough to the ECU logic to work.
Maybe just the vacuum switch. I'll think on it.

It is important to have the transmission locked more often that because it
builds heat way fast when the torque converter is slipping. The 700R4 design
and cooling depends on that torque converter being locked. 

I think the basic ECU logic is to engage when possible and disengage at a
high rate of change of throttle position, at closed throttle, and at WOT.
There is also some speed dependency I haven't looked at closely. I think the
idea to disengage at WOT and high rate of change of throttle position is to
make use of the torque multiplication you get with the torque converter
slipping under load and also to disengage when you are coming to a stop
(although, the circuit always disengages when the brake is applied).

Anyway, thanks for the ideas everyone.

_______________________________________

David M. Ingebretsen, M.S., M.E.
Collision Forensics & Engineering, Inc.
2469 East Fort Union Boulevard, Ste 114
Salt Lake City, UT 84121

801 733-5458
dingebre at 3dphysics.net

__

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Eugene Pilipanko
Sent: Monday, September 11, 2006 6:20 PM
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] Using GM '747 to control TCC lockup only

www.bulkpart.com    part # 74416ak.   Summit racing part # TCI 376600 or 
Jegs part 3 890-37660 should help you out.

---- Original Message ----- 
From: "Milosz Kardasinski" <miloszk at gmail.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, September 11, 2006 5:16 PM
Subject: Re: [Diy_efi] Using GM '747 to control TCC lockup only


> What I have seen in some applications is the use of a vacuum sensor
> connected to ported vacuum. You'd have
> to set the switch point to whatever you feel is the appropriate vacuum
> threshold...but all the sensor does is ground
> out, which engages the TCC below a certain vacuum setting. Some also 
> connect
> a switch in series to turn off TCC
> whenever the brake pedal is depressed.
>
> ----- Original Message -----
>
>>
>> I converted a Jeep 4.2 liter to a GM throttle body, works well. But, I'm
>> thinking of purchasing a MOPAR MPI conversion which was designed for that
>> engine.
>>
>> My dilemma is that I have a 700R4 automatic in the thing and like that 
>> the
>> GM ECU ('747) controls the TCC lockup. I will lose that feature in the
> Mopar
>> unit.
>>
>> Any ideas about the feasibility of using the '747 to just control the TCC
>> lockup?
>>
>> I think I can piggy back off most of the sensors the TCC logic uses; 
>> temp,
>> speed, MAP, but I'm not sure about the throttle position. I saw a cable
>> throttle position sensor which might work.
>>
>> What happens when the ECU isn't actually controlling the fuel anymore and
>> the closed loop logic gets feedback, but isn't controlling the system?
>>
>> Is there a better way to automatically control the TCC and disable the
> other
>> processing in the GM ECU?
>>
>> I just hate going to a switch on the dash. It's so "unelegant".
>
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