NH auto shifting issue

[klneedham]

I have a 92 Pajero JDM 4D56T with 4 speed AT and 276,000 clicks.

Transmission shifts from 1st to 2nd just fine (usually), but will not shift automatically into either 3rd or 4th unless I let off on the accelerator first. When I let off, she shifts just fine, no clunking, no slipping.

I was also starting to lose reverse, so I dropped the pan and changed the filter. I went for a ten mile test drive and all went well, 1-4 shifted fine, reverse much better. Next day, I had to back off on accelerator once again for 3rd and 4th, though reverse is still greatly improved.

I did add 1 pint of Seafoam's transmission conditioner (TransTune) to the new fluid (Dextrin III). Is it possible that it cleaned out enough grunge to clog that filter again, or is it more likely I am looking at a different problem?

PS. From time to time, especially in a crosswind, the transmission has trouble holding overdrive and will shift back into passing gear (3rd). Is this connected to the above problem, or is this normal for this vehicle?

[Dicko1]

At nearly 300,000 it would have been far better to have had a complete flush and refill of the autobox. You have only cleaned out a third of the oil and contaminated the new oil with the old crap. Not saying this is definately the problem but would certainly not be helping the auto box changing/holding gear.

[tomwithannl]

I agree with Dicko1 with regards doing a flush not just a pan off change but your symptoms sound a lot like your kick down cable may need adjusting (too tight).
Would be worth a try before anything else.

Tom

[klneedham]

At nearly 300,000 it would have been far better to have had a complete flush and refill of the autobox.

I tried to do this by filling the pan, running around the block, draining, refilling, running again, draining, etc. Did this three times. Not sure how effective this was, but I read it on one of these threads.

[klneedham]

I will check the cable. Thanks.