Slips out of overdrive into drive?

KEVINBD

MEMBER
1994 FORD AEROSTAR
3.0L
6 CYL
2WD
AUTOMATIC
160,000 MILES

I have a 1994 Ford Aerostar. When driving on the freeway at 65mph +/- in overdrive. The transmission will randomly downshift into drive and stay in that gear. When it downshifts out of OD, nothing I do (use the column to shift into other gears and back, into neutral and back) will make it up shift back into OD when I return to that gear. (Copied)

This has been going on for years now. I had the transmission shop look at it twice and each time they say the trans is fine. I replaced all sensors that can be related to the trans. Performance. Very first thing I did was replaced the fuel filter.

The above description was copied from a earlier member of your site. Maybe you can remember the solution. Thank you

8 Replies

KEN L

MASTER CERTIFIED MECHANIC
43,072 POSTS

So, there are two things that can cause this to happen, either the MAF sensor is off making the computer think there is less air going into the engine (load) or the catalytic converter is getting clogged causing eh same effect. Here is a guide and the location of the MAF sensor so you can check it out:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

These problems will not set a trouble code. Check out the images (below). Please let us know what you find. We are interested to see what it is.

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Saturday, December 10th, 2022 AT 2:31 PM

KEN L

MASTER CERTIFIED MECHANIC
43,072 POSTS

Yep, they don't say much about the pressure regulating solenoid, but I did find information on the OD gear issue.

From OD or D to 1 at 55 MPH Coasting, shift to first under 15 MPH See: Automatic Transmission-Transaxle - Symptom Related Diagnostic Procedures - Kickdown Shift Speeds Too Early

1. Main control pressure malfunction.
2. Sticking or dirty valve body.
3. Low/reverse servo damaged.
4. Governor damaged or worn.
5. Overdrive clutch damaged.

Check out the images (below). Please let us know what you find.

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Monday, December 12th, 2022 AT 12:06 PM

KEVINBD

MEMBER
3 POSTS

I looked over the list of possible causes for my transmission slipping out of 4th into 3rdthat you sent. None of them seemed to reflect what has been going on for the past 3 years. The closest one would be trans valve body going bad, but research says that it would not last 3 years with this issue. One thing I neglected to say was it will also shift from 4th into 3rd on the highway if I hit a bump in the road. Driving down the highway just fine I hit like a overpass break in the road and down shift it goes. I have pulled over and stopped before and shift the gears and pulled out on the highway but still would not shift into 4th. Thanks, Kevin
PS: I bought another MAF sensor and will try this again but remember I replaced the one I currently have just 2.5 years ago. I'll let you know if it changes anything.

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Wednesday, December 14th, 2022 AT 9:57 AM

KEN L