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3-4 shift issues, power loss

1187 Views 6 Replies 3 Participants Last post by  Crak88lx
Still working on the Turbo Swap, 88 T,bird into a 90 Mustang. Using an A4LD in the Mustang. I drive it, it shifts fine 1-2 and 2-3, but at about 45mph it acts like it wants to shift again, but will suddenly lose power, not shift and slow down. I can take my foot off the gas, and then speed up slowly and it will shift and I have power again. Also, when the power goes away, the engine light comes on, when the engine light goes off the power is back. At the loss of power the vaccum will go from around 0 to 20 all at once. about 1 out of 10 tries it will shift all the way through and work fine. This is a 2 wire A4LD.

Codes 81, 82 83, 85 and 88.

I am just not sure what is the instigator of this problem. It seems like it is the transmission, but I am wondering if I have some electrical something that is happening that would cause the same problem even if I had a manual tranny in it.

Is there a difference in a modulator valve for a 2 wire vs a 3 wire A4LD?

Any ideas on where to attack this would be great!
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No insult taken. I am grasping for ideas! I think my fluid is good, but I should check again to be sure. I think I have all the vacuum lines tight, but again worth another look. Thanks for the post!
Really interested in the code 85. I see it says the 3-4 shift, but what does that mean? This has been a long term project in my spare time (ha), so it has drug out over time. I had the tranny rebuilt so feel certain I have a good filter and new fluid. I am not positive whether I have the Mustang transmission in it or the Thunderbird transmission in it. Only after putting all back togeter did I learn about the 2 wire, 3 wire difference. The 2 wire is in the car, the 3 wire is sitting in my garage floor. Could it be the computer is trying to make the 3-4 shift electronically when the 3rd wire is not there and causing some sort of reaction?
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