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To Go Beyond
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1,143 Posts
Discussion Starter #1
Hey all!

I have a 98 Supra that was converted not too long ago from N/A to BPU-TT. I had a full complete swap done including: Motor, Tranny, Differential, Axels, ECU, etc.

The Motor and everything came from a 94 US Supra. It was an auto to auto swap.

Everything works fine except for one thing......

When you drive any automatic vehicle and press on the gas peddle, depending on the amount of pressure applied the car will accelerate accordingly. If you push the peddle to the floor, the car will downshift to give you faster acceleration that you are asking for. We all know this.

Here is my problem..... If I have the car in drive and roll from a stop it will go from first gear immediately into final gear (4th). It does not shift to 2nd and it stays in 1st for only a second or two. If I am driving in final gear and stomp on the gas, the car will continue to putt along. The only way to get the car to move properly is to manually shift it from 1st, to 2nd, to 3rd, to O/D (4th). As well, when slowing down to a stop, the car will not downshift until like 5mph, then it will drop from 4th to 1st.

What is wrong with this and why is the transmission not shifting appropriately as an automatic transmission should?

Any known fixes or suggestions would be very very appreciated!

Thank you all for your assistance!
 

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To Go Beyond
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Discussion Starter #2
Anyone?????
 

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To Go Beyond
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Discussion Starter #4
Tranny ECU??? I am sorry, just not literate when it comes to transmissions.
 

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Surpass said:
Tranny ECU??? I am sorry, just not literate when it comes to transmissions.
Well then your going to have a terrible time trying to fix it. It sounds like the Tranny ECU is messing up. Did they reconnect everything after the swap? I don't recall the JDM auto being any different and should be plug and play.

Take it back to the shop that swapped it, or take it somewhere else you trust if they were shady...it'll make your life easier.
 

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To Go Beyond
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1,143 Posts
Discussion Starter #6
Well you said JDM again it is US to US, not JDM.

Anyway, yeah I am going to take it to a buddies shop tomorrow to have him look it over.

Where exactly would the tranny ECU be located?
 

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Let us know what you find out please, cause my Transmission does the EXACT Same thing. Only it's a Built NA Auto with JDM 2jz. But the symtoms are the same. I was told I needed to rebuild my tranny and that the 2nd gear clutches or V-Band or something was burnt up. I really need to take it to the shop and get them to drop the pan really really see what it is. Hopefully it's somthing simple as a loose connection. Good Luck.
 

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Boost Junkie
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12,615 Posts
Check your sensors and check the main ecu and the trans ecu. It sounds like an incompatibility issue with the way you describe it.

Steve
 

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To Go Beyond
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Discussion Starter #9
Where would the incompatibility be?

It is a 94 motor with 94 harness with a 94 ecu. The only thing 98 is the body electrical.

Does this help?
 

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To Go Beyond
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Discussion Starter #10
Bump
 

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To Go Beyond
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Discussion Starter #11
Ok, well a couple of you mentioned a tranny ecu. I called Toyota about it and they said none of the supra models have a seperate ecu for their tranny. And, if this is "where it would be", its not under my passanger floor with the main ecu.

What's up with this?
 

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WE BRUNG IT HARD!!!
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check ur speed sensor clip by the bottom of the car by the tranny. if clip is disco it will be ecu problem. i suggest aem and that will end most ecu problems just my .02
 

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yep...AEM will help, my trans does the sae problem. Maybe you could get another ecu from someone. But for sure AEM
 
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