no upshift 4R70W after converter change - Ford Mustang Forums : Mustang Forum
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post #1 of 2 Old 06-01-2014, 12:32 PM Thread Starter
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no upshift 4R70W after converter change

I have a 97 4.6L TBird project car that upshifts at 5100 rpm WOT. After installing a 3800 stall converter last year I had problems with an early 1-2 (4700) and late 2-3 (5500) shift. It had a Hypertech chip. I removed the chip and I'm using a SCT 3015 controller. Now it won't shift 1-2 at WOT at all. I've let it go to 5900 and still no shift. At 90% throttle it will upshift, no problem. The speedo is correct however I even tried replacing the 20T speedo gear with a 17T to make the speedo read about 10 mph higher but no upshift. The controller doesn't seem to have a WOT rpm change only a mph change which hasn't fixed it either. I've used an old Ford Trans tester that allows manual upshifts using an electrical switch which I can shift without any problem. Anyone run into this? Thanks.....Ken.

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post #2 of 2 Old 06-11-2014, 09:23 AM
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Pull the converter and replace the O ring on the shaft. Probably got damaged and will not allow tranny to build enough pressure...

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