First off, great post.
I bought a 1989 Ford Ranger XLT with the 2.9 V6, A4LD Automatic Transmission about 6 months ago, and loved it, but it shifted a bit rough into second sometimes, idled pretty rough, and chugged when decelerating dropped it below about 1000 RPM. I wanted to try and make some improvements to it.
My Grandfather and I saw immediately that the vacuum line elbow connections coming off the Fuel Injector were very loose. We changed them out, and charged the AC (which still does not blow cold due to what we believe to be the electrical wire from the pump). The Ranger drove like a dream for 2 days. Shifting super smooth, idling smoother, and chugging greatly reduced. Third day, I backed out of driveway, drove down to the stop sign at the end of the block, and once I stopped and went to accelerate, it just revved up like it was in Neutral. I ran the shifter, which is on the column, through the gears to park and then back, and it drove like normal with no problems. Next night, the same thing happened. Once again it drove like normal for awhile. However, leaving work the next evening, it was happening at several stop signs, so I made it home as quickly and with several prayers and put it in the garage.
I did some research and saw that a vacuum modulator could cause similar symptoms, and I thought with changing up the vacuum lines it could make sense (I am no mechanic, obviously), so I cut off the rusted catalytic converter, which was a terrible experience, and replaced the vacuum modulator and Catalytic converter.
Once complete, the Ranger would shift and transition through all of the gears on the column shifter, but when driving would not transition out of first gear. It would just drive in first gear. I could manually shift it on the column into second and it would shift into second, but not automatically shift out of first while driving in drive or overdrive.
I had purchased everything to follow the valve control body rebuild diary, so I thought I would go ahead and take the opportunity to do so. The 1-2 transition valve in the control body would compress and stay compressed. I felt pretty good after reinstalling that I had fixed the issue with the rebuild, but once everything was put back together, the Ranger will now not shift into any gears. Every gear I put the column shifter into just revs up like in Neutral. At one point, there was a glimmer of Drive, but nothing useful. I can hear it and feel it clicking through the gears, but no reaction in the transmission to it.
The suggestion was made that my issues could be from not having enough vacuum, and also that my it could be in my solenoids. I was just wondering if there was any advice for going about checking it out, as my attempt to improve this truck have made it a little worse each time, and left me feeling pretty defeated.
I love the truck, knew it was going to be a learning experience, but thought I would at least be able to drive it as I progressed among the projects.
I checked the levels of the fluid, turned on the Ranger, and checked them again, and there was a good drop in the fluid. I added some more fluid, and it started to engage in all of the gears as I shifted on the column. During a quick road test, I found that it is back to where it will not automatically shift out of first gear into second in drive or overdrive. I can manually shift into second gear on the column, but it will not transition normally while driving.