View Full Version : 4R70W overdrive shift weirdness

07-05-2017, 05:01 PM
Okay - so I have a 2003 Mustang 4R70W in my 1994 SC. When I did the swap (my old one died) I swapped the old valve body out of the 94 trans along with wiring harness. Refilled with brand new fluid. Two years of good operations with little to no oddity. The wrecker claimed 4000 miles were on the car when it was totaled and I believe it - VERY clean fluid (but replaced anyway).

On to this week - 1200 mile road trip up to Bellingham, WA over to Richland, WA and back to the Willamette Valley. Stock trans cooler (radiator). Stock temp gauge never went over "m" in norm.

The issue - on most occasions when shifting from 3rd to overdrive in normal driving conditions the tach will go from the usual 2000RPM that I'm pulling all the way up to 3500-4000 before shifting into overdrive. If I let off the throttle as I shift into overdrive the shift behavior is much more normal. If I hammer the car from red light or onto a freeway on ramp it shifts as it usually should. I'm looking for the symptom in the book to read up on but cannot find it. Any ideas guys?

Oh - searched the forum for 10 mins via search tab but could not find similar threads for reference... Any advice would be appreciated.

07-05-2017, 05:18 PM
I understand swapping the electronics over, so they work with the SC EEC unit, but why would you use the original valve body? I'd start there. Was the valve body at least gone through as per the J-mod instructions on Tccoa? Could be something sticking internally after this much mileage.

sam jones
07-05-2017, 08:47 PM
Good evening

This is the website I go for additional information of AOD/AODE/4R70W transmission. For your specific issue it might be the problem between the valve body gasket and or the servo.


Good Luck.

07-05-2017, 11:41 PM
I'm having trouble remembering but I think I only did the electronics. The next weekend I have time to play I'm going to drop the pan and look at the overdrive servo.