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Guest Message by DevFuse
 

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TC Lock Up??


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3 replies to this topic

#1 Hocrest

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Posted 24 May 2005 - 04:37 PM

On the SVX race car that me and Benebob have been working on, we currently have a transmission out of a FWD Impreza 1.8. We are using the SVX TC and the SVX TCU... Now that we have some of the other issues worked out, we noticed a "bogging" while stomping it about 1/2 way through 2nd. It always seems to happen at the exact speed/RPM.

At first we though it was a fuel issue, this afternoon at about the same time we both had the though of early TC Lockup???

Does this make sense to anyone else??? Can anyone tell me how the TC locks? I'm guessing a signal from the TCU to the trans. i checked out the FSM I have here for an XT6 (basically the same 4eat) and it looks like maybe Sel B is responsible for Lock Up?? If we find the wire going to Sel B and disconnect it would that keep it locked or unlocked?

My other thought is to try out a TCU from the Impreza and see if that will help it shift better?

For now the car is being run in auto crosses only, so I really don't care if the TC never locks again.

#2 All_talk

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Posted 24 May 2005 - 04:58 PM

Does the SVX TCU have the “Power” mode like the turbo cars? If not, a turbo TCU might be some help, I’ve even read about a way to lock the TCU in power mode.

TCU pinout scans:

http://www.main.expe...U_I-O_page1.jpg

http://www.main.expe...U_I-O_page2.jpg

Yep, looks like Duty Sol B is the lock up (check page 2 scan), looks like all you have to do is cut that pin (or add a switch that opens the circuit). The TCU will most likely throw a code, you might trick it (if you care) by having your switch short in the proper resistor, but if the TCU measures TC slip it will most likely throw it anyway.

Gary

On the old GM autos it was a separate connector and you could just unplug it… no such luck with the Subie.

#3 Legacy777

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Posted 24 May 2005 - 09:51 PM

Lockup does not occur under full throttle acceleration. So I wouldn't worry about that causing the bogging.

Does the bogging occur in 1st gear at all? Where in the RPM range does the bogging occur in 2nd gear, and at what speed? Is it the same all the time?

#4 Hocrest

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Posted 25 May 2005 - 06:31 AM

Lockup does not occur under full throttle acceleration. So I wouldn't worry about that causing the bogging.

Does the bogging occur in 1st gear at all? Where in the RPM range does the bogging occur in 2nd gear, and at what speed? Is it the same all the time?


I know it isn't supposed to happen at full throttle, but we aren't running a typical set up...

It's hard to give an RPM and speed, as when this occurs we are out on course. More concerned with cones than the dash. But it did happen at the same spots on the course, with different people driving. Also if you get off the throttle and slam it back down it will accelarate normally (incredibly:brow: ).




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