Manual Shifting Out of Phase

[RocketeerPerformance]

So...the day that the new owner came over to pick up the car a completely new issue popped up with the transmission (Murphy's law?). This only happens when manually shifting the tranny. When going to 4th, it stays in third and the only way to get it to go into 4th is to turn off the car and keep it in 4th. It will also go from 4th to Neutral. I looked at the troubleshooting guide but most of the suggestions there are presuming that you are in in D all the time. The closest I could find would seem to be the valve body. To me it seems almost as if there is some kind of position sensor that isn't working correctly. But, why only when shifting manually? TIA and sorry if this has been discussed but I didn't see the title as being the same.

 

[gsxr]

Any chance either of the 2 shift bushings are worn? There should be zero play at the shift lever.

If the shifter is ok, I agree that it seems like a valvebody anomaly. Assuming the problem is always at part throttle, the shifts are 100% mechanical with no sensors or electrical components involved. Also make sure the fluid level is at MAX with the trans fully hot. Not in between min & max, definitely at MAX. Does the same problem occur both cold and hot?

I've never heard of this exact symptom before. Weird!

 

[Duh_Vinci]

If it's valve body issue, possibly easy to look at #7 plunger/selector, with transmission pan off, with 2 people, so whoever is under the car can see if the movement of that plunger is adequate through all the manual shifts? I don't recall that plunger has any valves within in it, literally just a mechanical "syringe" ... Maybe some debris accumulated in it's receiving cavity?


722.3_valve_body by Duh_Vinci, on Flickr

 

[RocketeerPerformance]

It only happens during manual shifting at hard throttle. Light throttle is fine as is leaving it in Drive. Taking it in to the mechanic tomorrow.