Downshifting, won't hold gear

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
Sgramling
Posts: 1
Joined: Fri May 08, 2020 3:53 pm
Location: SOUTH CAROLINA (SC)

Downshifting, won't hold gear

Post by Sgramling »

Greetings all! I am new to the forum and E24 ownership. I have had E30s but this is my first 6.

My 1987 with Auto trans has a weird issue. When in 4th gear if traveling up slight hill or anything other than very little throttle apply, the trans downshifts into 3rd for about 1 second and then will shift back into 4th. It will continue one doing this as long as you maintain anything more than light throttle. If I put the selector switch to 1-2-3 it will hold 3rd fine. Also holds 3rd in Sport mode. It seems like it wants to downshift earlier than it should but jumps right out. If I apply heavy throttle from acceleration it holds all gears fine.

I can't find anywhere what commands the downshift. I don't see a knockdown cable so I am assuming its based on throttle input? Should I adjust throttle cable, test TPS, or is this indicative of a transmission sensor issue? Thanks in advance!
Post Reply