93 premature shift

[mikieem]

I have noticed that the tranny premeturely shifts from 1st to 2nd. That is the only problem in shifting. If I shift manually from first to second, 1st gives me no problem at all. Any ideas?

[fredjacksonsan]

Prematurely how? Right away, or after 15-20mph? In some transmissions the shift schedule allows 1st to get the vehicle rolling then a quick shift to 2nd for acceleration; I've had this on many vehicles.

Try a full throttle takeoff and it will probably hold 1st much longer.

[mikieem]

Even on WOT it will still shift early. I've had the truck for 9 years. It sat for a few years and now it's my everyday driver again. Even if I am rolling at say 20mph and floor it, it will not downshift. Also, if I am to upshift manually, first will stay until I shift into second but if I go from 2nd to drive it will jump back to first then to drive. I am completely lost.

[fredjacksonsan]

You haven't said what you mean by "Prematurely". Please give some parameters so we have something to go on.

[mikieem]

The rpm's will not go above 2,000 before shifting even with wide open. Even when playing around at say 20mph and then punch it, it still won't downshift.

[fredjacksonsan]

Do a search under "TV cable" in this section and also the Cherokee section. There is an adjustment you can make that might help.

Usually the tv cable causes the no downshift. The rpms not getting above 2000 at any time on the 1-2 shift points to something different IMO. How is the fluid level in the trans, and how long has it been since the trans fluid has been changed?

There was also a recall on some 90s models with V8, for catalytic converters that had the matrix crumble and clog up the exhaust, prohibiting rpms from rising. Have your converters ever rattled at idle? Can you get it above 2000 rpm on say a 2-3 shift?

[mikieem]

It has been a while since the fluid has been changed. I was thinking if I had it flushed, that would solve it. I wanted to check on here and see what you guys may have thought. As for the cat, well I know it is not the problem because when I first bought it in '02, ,the muffler had a small hole and the cat had a small rattle, so being in high school and auto shop I did what any 17 year old would on a 5.2 jeep, I hollowed out the cat and threw a 40 series flowmaster on it. Eventually it was too loud for me and I threw another cat on. I may just end up changing the fluid by dropping the pan one day myself to see if that may help it. It does have 150,000 and I really don't remember ever changing it if I didn't when I first got it.

[fredjacksonsan]

The way I understand it, flushing would be a bad idea at that many miles as it will push the crud you don't want to where you don't want it.


IMO it's best just to drop the pan, change the filter and refill, and repeat a couple times at 15-20k intervals. Then you'd have changed out almost all the fluid.

You could also try AutoRX to clean things up in there, can't hurt.

[mikieem]

That may be what I end up doing. Thanks and I'll keep you posted on the outcome.