Slip-like shift between 3rd and 4th gears, maybe, possibly

I noticed recently that the shift between 3rd and 4th gears in my '98 is hiccupping a little bit. I've never had transmission problems before in any of my Rivs, so this is uncharted territory for me. I should mention this car has only 70K miles on it, but the previous owner did snot for maintenance.

It shifts perfectly smoothly 1-2 and 2-3, but between 3-4 after it shifts, the RPMs bump back up a little bit. Let's say I'm accelerating and the RPMs hit 2000 in 3rd gear like normal, then shifts back down to 1000 in 4th gear, and then they jump up a little bit to about 1300 before settling back down to 1000 and continuing to acclelerate normally. It doesn't sound like classic "slip" as I understand it as the RPMs drop normally before the hiccup, instead of surging before dropping... but that might be my subconscious just hoping and praying, haha.

Slip? Lunge? Etc? Empathetic reassurances it will all be OK in the end and restoring this beauty will be the most soul-enrichening experience of my life? Hah. I'm trying dearly to love this car like my last Rivs but she's bleeding me dry!

If I understand you right mine does the same thing. Coasting down the highway I'll tap on the gas when I need to and it'll go up a bit then settle back down with my foot still on the gas. Not sure if it's shifting down to third or not because I don't feel any shifts.

That's the Converter disengaging and locking up again. It almost acts like it has a 5th gear. Hit the gas enough in 4th, and it will "disengage" the converter to let the car accelerate. Off the gas, and it locks up again. It's normal unless it's happening way too often. You'll start to notice it more often if the TCC solenoid starts getting clogged (most common issue).
You can make it happen in 3rd gear too. Put the shifter in "3", and drive about 40mph. You can get the converter to slip in and out of lockup.....

Ohhhh that makes sense. It does seem worse when I'm light on the gas as opposed to harder. It happens between every single shift between 3 and 4 though. Probably falls under the "way too often" category. Meep.

It will happen almost every single 3-4-lockup shift. Lockup is the very last thing the transmission does to cruise. Take a ride. You can literally make it happen on command. Some cars are more noticeable, some aren't. If you have an aftermarket Intake or MAF, it may amplify it (firmer shifts).
I wouldn't worry about it unless it starts slipping in/out of lockup even if you're off the throttle.

Try adding a gear and loud exhaust. Makes it wayyyyy worse. Literally sounds like it has 5 gears   

Hah! Then I'm a step ahead of you. The exhaust came loose somewhere over the weekend and it's definitely louder than usual. Maybe I'll just let that go. People pay good money for that kind of growl, right?!

Ha. That explains the complaint. You can hear it now.....

Initially I noticed a little while ago when I had a new engine put in the car (threw a rod two weeks after I bought it) and I was being really nitpicky about everything. But yeah, the exhaust may have irked me to the point of finally posting about it, haha.

gunmetalRED wrote:

I noticed recently that the shift between 3rd and 4th gears in my '98 is hiccupping a little bit.  I've never had transmission problems before in any of my Rivs, so this is uncharted territory for me.  I should mention this car has only 70K miles on it, but the previous owner did snot for maintenance.

It shifts perfectly smoothly 1-2 and 2-3, but between 3-4 after it shifts, the RPMs bump back up a little bit.  Let's say I'm accelerating and the RPMs hit 2000 in 3rd gear like normal, then shifts back down to 1000 in 4th gear, and then they jump up a little bit to about 1300 before settling back down to 1000 and continuing to acclelerate normally.  It doesn't sound like classic "slip" as I understand it as the RPMs drop normally before the hiccup, instead of surging before dropping... but that might be my subconscious just hoping and praying, haha.

Slip?  Lunge?  Etc?  Empathetic reassurances it will all be OK in the end and restoring this beauty will be the most soul-enrichening experience of my life?  Hah.  I'm trying dearly to love this car like my last Rivs but she's bleeding me dry!

if you are still running Dexron III fluid, switch to Dex 6 and change your filter. GM's not policing the Dex III standard any more so it's tough to get good Dex III. Dex VI will be fine.

And once you make the switch NEVER switch back.

Albertj

Oh that's interesting, I didn't realize they're not making that grade anymore. I'll make the switch. It needs a fluid exchange anyway I'm sure. It's probably the original fluid.

By the way, just so we're all talking about the same symptoms here, I uploaded a short video to YouTube of my car shifting through its gears. You can watch it bump right after the last shift. https://youtu.be/v6NVKXkkqig

gunmetalRED wrote:

Oh that's interesting, I didn't realize they're not making that grade anymore. I'll make the switch. It needs a fluid exchange anyway I'm sure. It's probably the original fluid.

\

They still make the fluid. We have it in a giant 250 gallon tank here at the shop. It's just that GM doesn't have any vehicles that use Dex III anymore. Everything uses Dex VI. You can top off Dex III systems with Dex VI fluid, but you can't use Dex III in a vehicle that was designed for Dex VI.
We still put it in the cars that use it unless the customer requests the "upgrade".