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

[Leo Schneggenburger]

Hi David,
 I just happen to be a transmission specialist and yes, you need lock up 
unless you have really low (high numerically) rear gearing. I would 
recommend the vacuum setup as with proper adjustment it will 
automatically unlock under higher load conditions as it should. Hope 
this helps.
Leo

David M. Ingebretsen wrote:
> 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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>>
>>     
>
>
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