Solved Erratic overdrive on a 4.0L 1995 Aerostar.

[CLTuna]

The story, I was driving Thursday night when I came upon gravel patches perpendicular to roadway. After a three minute bumpy ride at 35-40mph I turned off onto a smooth highway. While accelerating toward 60mph the transmission stuttered when shifting to overdrive. I slowed to a stop, shifted back to park, paused and tried it again. This time it shifted into 4th fine. Drove another 10 miles at 70+ mph with no issues. No CEL..

Drove it again Saturday. This time it stuttered a bit when shifting to 4th. I gently accelerated to 70mph. Then the CEL appeared. I slowed below 40mph and shifted into 3rd. In 5 minutes the CEL went out and I finished the 30 mile trip in 3rd. On the return home and this time with the AC on the van seemed to hesitate a bit while in 3rd. No CEL. I noticed the van didn't seem to have the power it normally does. It was also running hotter than normal.

(Sunday) A few minutes ago I jotted down the KOEO codes using the CEL flash method. I got these codes:
85 - Canister Purge Solenoid circuit failure
86 - 3 to 4 Shift solenoid circuit failure
87 - Fuel Pump primary circuit failure

I also checked the trans fluid level and it was above cross-hatched area of dipstick.

Just two weeks ago i drove it over 800 miles and it operated normally.

Is it possible that a connector shook loose?
Maybe the trans fluid isn't circulating?

 

[CLTuna]

The story, I was driving Thursday night when I came upon gravel patches perpendicular to roadway. After a three minute bumpy ride at 35-40mph I turned off onto a smooth highway. While accelerating toward 60mph the transmission stuttered when shifting to overdrive. I slowed to a stop, shifted back to park, paused and tried it again. This time it shifted into 4th fine. Drove another 10 miles at 70+ mph with no issues. No CEL..

Drove it again Saturday. This time it stuttered a bit when shifting to 4th. I gently accelerated to 70mph. Then the CEL appeared. I slowed below 40mph and shifted into 3rd. In 5 minutes the CEL went out and I finished the 30 mile trip in 3rd. On the return home and this time with the AC on the van seemed to hesitate a bit while in 3rd. No CEL. I noticed the van didn't seem to have the power it normally does. It was also running hotter than normal.

(Sunday) A few minutes ago I jotted down the KOEO codes using the CEL flash method. I got these codes:
85 - Canister Purge Solenoid circuit failure
86 - 3 to 4 Shift solenoid circuit failure
87 - Fuel Pump primary circuit failure

I also checked the trans fluid level and it was above cross-hatched area of dipstick.

Just two weeks ago i drove it over 800 miles and it operated normally.

Is it possible that a connector shook loose?
Maybe the trans fluid isn't circulating?

Update: Went to shop and had test done. Codes were 185 Mass Air, 186 Injector width shorter and 187 Injector width longer. I had the mechanic clear the codes. He then ran a running engine diagnostic test. After snapping the throttle (Code 10) the test finished and gave Code 11 System pass. I left and drove it on and off three interstate ramps and it performed normally. No more stuttering into OD, no CEL. Operating coolant temp. back to where it is normally. Checked the trans dipstick and back in cross-hatched area. WTH?? My guess is the MAF sensor vibrated on rough road causing issues. I'll post back after a couple days of driving or if CEL's reappear.

 

[BrooklynBay]

Did the check engine light reappear?

 

[CLTuna]

As far as the tranny dipstick, it's difficult to read accurately. Had to try several times. Finally I came to the conclusion it was overfull by about a quart. I just did a AT filter change about 9k ago. I warmed engine, then shut it off and used a common fluid pump to extract about 2 1/2 quarts. Started engine and slowly brought the level to the middle of the hatched area.Had to insert the dipstick many times to get near accurate readings.

Now for the hesitation shifting in overdrive. There was a slight miss in the engine that I began to notice more. This happened before when the pass. rear plug was fouled. I researched the best way to change plugs from your forum posts. Jose A.'s advice worked for me. I changed all the pass. side plugs and started engine, no difference. Changed the driver's side plugs, the last plug to change, #6 was wet and electrode burnt to a point. See I had a "reputable" shop change the plugs two years ago. There were three different plugs in the motor. I couldn't make out one of them but the other two were #765 and AP605. I installed all AP605's. Once I changed them the Aerostar ran smooth again. Took it for a highway spin, no issues. You guys are the best and saved me a bunch of dollars. Thanks for looking in on my problem. How do I contribute?

 

[BrooklynBay]

Thanks for the update. Your thread is now marked solved. What kind of spark plugs did you use? You could contact Rick, and ask him to send you an invoice to increase your existing elite membership.

 

[CLTuna]

Thanks for the update. Your thread is now marked solved. What kind of spark plugs did you use? You could contact Rick, and ask him to send you an invoice to increase your existing elite membership.

I installed all AP605's.