A4LD, early 1-2 shift in OD

[WhiteLX]

A4LD, 4th gear always engaged in OD

This is a Ford reman 2.9L A4LD in my 2wd Ranger with probably around 40K. It is a 2 solenoid version. In Drive there transmission shifts normally for 1-2-3 and TCC lockup. However, with the transmission in OD, the 1-2 shift is having issues. When cold the 1-2 shift in OD will function normal. After the first couple miles the 1-2 shift starts ti have trouble. When accelerating very slowly (slower than normal pace of traffic), the transmission will shift 1-2 normally. However, under normal to hard acceleration, it feels as if it starts in 2nd gear. I can only count 2 shifts as well and it's definitely going into OD and TCC lockup. There is a slight stumble upon initial acceleration in these cases, and what I believe is happening is it is performing the 1-2 shift way early, so early it seems as if the truck is actually starting in 2nd. I can move the shifter to D at this point and the truck will downshift to 1st.

Any ideas what could be the cause? I am thinking something in the valve body isn't quite right. But why the difference between shifting performance in D vs OD? I had planned on getting the Transgo shift kit as well as the large ratio boost valve, the manual valve indexer, domed relief valves, ZC servos, and the Sonnax O-ring plug kit. However, I'd like to know if these items will fix the issue before spending the money on parts that may not improve the problem.

The transmission also suffers from delayed reverse engagement, but no delay when going into D or OD.

 

[JK080]

I have had a 3-4 solenoid cause this kind of problem, what ends up happening is the overdrive band is being applied (4th gear) and it feels like 2nd gear but its just a overdriven 1st gear.

Aftermarket solenoids will fail like this too, only use OEM and not the one that uses the screen in the sleeve

I wouldn't get anything else other than valve body gaskets right now, those other parts won't correct this.

This is the solenoid and its the latest design without the screen.

 

[WhiteLX]

makes since. I had considered that has well.

 

[WhiteLX]

Bringing this back up as I have been thinking about this for a bit. If it were the solenoid sticking/failing, wouldn't the issue still occur with the shifter in the D position? When in D, the transmissions shifts as normal. Once I get above 40-45mph crusing, I pop it up into OD and it shifts to 4th. As I slow down I shift back into D and it shifts like normal up and down.

The issue only exists with the shifter in the OD position. Also, when the transmission is cold for the first few shifts in OD it shifts correctly. After a few shifts it returns back to having OD engaged all the time.

With the computer controlling the 3-4 solenoid, what's the difference between having it in OD or D when at lower speeds? Obviously the computer has turned off the 3-4 solenoid. If I have it in OD at low speeds, I can move the shifter to D and it will immediate disengage OD, this can be felt as a downshift, which shouldn't be occurring in 1st gear. If the solenoid were sticky it shouldn't matter if it is in D or OD, unless there is something else that is controlling fluid flow to the 3-4 solenoid or 3-4 shift valve that is changed when moved to D.

Could it be the 3-4 shift valve (BORE 201) is the problem?

I'd hate to drop the pan and VB, change out the solenoid, and that not correct the issue.

 

[JK080]

The manual valve sends oil pressure to the back of the overdrive shift valve in the OD range, in the manual ranges this oil pressure is cut off so it cant stroke the shift valve. This is why it only happens when you are in the OD range.

To help isolate the problem unplug the transmission, if the problem is still there the problem will be inside the transmission with the valve body. Either the valve is stuck in the applied position or the solenoid is faulty.

If the problem disappears it will be an external issue like a shorted OD signal wire.

 

[transman304]

The manual valve sends oil pressure to the back of the overdrive shift valve in the OD range, in the manual ranges this oil pressure is cut off so it cant stroke the shift valve. This is why it only happens when you are in the OD range.

To help isolate the problem unplug the transmission, if the problem is still there the problem will be inside the transmission with the valve body. Either the valve is stuck in the applied position or the solenoid is faulty.

If the problem disappears it will be an external issue like a shorted OD signal wire.

Great description James!