pb4ugotobed

I'll start by saying that I've never seen a tranny act like this before... It's a 91 4runner, 3.0 auto 4x4. It's honestly almost got me thinking computer rather than tranny problems from the tranny itself. Here's the problem... (when it happens) it'll slip pretty bad from a stop in 1st gear. Occasionally it will chatter, but that's only happened a couple times and only when you're (again) going from a stop, and step on the gas pretty good.

I've checked everything that makes sense... fluid is correct and at correct level. TV cable is adjusted correctly, etc.

Here's the weird part... half the time it's perfectly fine. warm, cold, doesn't matter. Drives great, doesn't slip, chatter, shifts smooth, etc. acts perfect.

other times i'll get in and it slips from the start. Weird thing is, like i said it isn't temperature dependant. I can drive for 45 minutes both city and highway driving, and it'll slip in 1st gear. then run into a gas station for a soda or something, pay for it, start it back up again and it won't slip one bit, acts perfect. Could also be vice-versa. Drives perfect, stop get gas, leave and it's slipping. It appears that cycling the key can (but doesn't always) affect it. I've not yet figured out the pattern to see what sequence of events causes it to either slip or not. It's really kinda aggrivating.

I've replaced this transmission a couple months ago because the previous one was doing the same thing! Only thing is, I parked the truck one day, got in it the next morning and it wouldn't move. Before that happened, it was doing the same thing this one is.

Also on a couple instances, (going weeks without using 4wd mind you) i'll get in the truck to take the kids to school, pull out of the garage, start driving up the street and it's in 4 low range (but the dash light isn't lit). Definitely in low range though, speed maxes at abou 30mph, and shift patterns match low range. Then by the time I realize that it ain't right, and go to pull over, it'll clunk, and it's back into normal range and drives fine. It's only done this twice to me, and it's been quite a while since it did. Just seems kinda weird to park it in 2wd, then the next morning it's in 4low. Don't know if the front driveshaft/axles are spinning or not, I have manual hubs and only lock them when I'm going to the trails.

Any ideas? I'm stumpedd

pb4ugotobed

nobody's had any issues similar to this?

4x4runr

Sounds similar to mine.....so I swapped a manual trans and never had a problem since. I spent so much money trying to find out why there was such a loss in power. 1st gear kept slipping, almost got hit by a bus because the dang thing wouldn't move!! Most probably the torque converter...but not too sure since I changed the whole trans system. Good luck!

pb4ugotobed

The old torque convertor was bad. It was replaced with a known good unit, so i know that isn't it.

I'd love to swap it to a 5 speed, however I've sold my other truck so this is now my DD and I just don't have the time to down it for a week to do the swap.

Honestly if I'm gonna spend that kinda money and down it for a week, it's gonna be down for more than a week and it's gettin a small block chevy, a turbo 350, transfer case of my picking and a pair of dana 60's or rockwell's. Which will eventually be the fate of it anyways, but that's probably a couple years down the road. For now it needs to stay streetable and DD'able

InternetRoadkill

If 1st gear is slipping, but not the others, it suggests that the 1st gear friction plates are either worn out or not getting enough fluid pressure to fully engage them. Unfortunately, you are likely going to have to take it apart to see what's going on. You might take it to a tranny shop and have them do a pressure test. It could be just a blocked filter.

pb4ugotobed

If it were friction plates then why wouldn't it slip all the time? I can literally have it slipping, shut the truck off for 2 minutes, start it back up and then it's perfect. I have an extra tranny (my old one) I was gonna pick up a rebuild kit for it and replace everything. Just been too busy to get around to it.

I've put a set of gauges on it, and pressures are good. The filter is also clean. BEfore I put the tranny in I made sure to spray it down real good and make sure it was good and clean. It was clean before I cleaned it, but just to make sure. Also there isn't or wasn't an abnormal amount of stuff built up on any of the magnets in the pan.

I'll probably just rebuild it and see what happens, but like I said I'm not totally convinced I don't have a computer or electrical problem of some sort.

InternetRoadkill

Unplug the computer and shift it manually.

Lotus1

have you replaced the shift solenoids? That's what solved my problem.

Takenover

Known good unit? Those are cheap enough to replace with a new one whenever you have enough labor invested in having it out.
Toyota trans solenoids dont go bad as much as people think.
Is it possibly starting out in 2nd when its slipping?

pb4ugotobed

Well, it really isn't all that big of a deal to swap out the tranny. If i were able to get on it and stay on it, could have probably done it in 4 or 5 hours. Not really that big of a deal, even working on it a litle here, a little there still had it done disconnecting lines, linkages, wiring, etc for an hourish in an evening, and starting on it the next morning around 8ish had it done by 2pm the next day. That was replacing the rear main seal, starter contacts, and some other stuff at the same time. Not major stuff, but 'while i'm in here' kinda stuff. I have 125 bucks into the tranny, could probably have scrapped my old one for almost as much.

When it slips, it seems to 'catch' at about 20mph and then holds solid and goes great from there. I was wondering about the starting in 2nd gear thing as well. However I'm pretty sure that wouldn't explain the occasional chatter during slippage. I do agree with you, it isn't really common for the solenoids to go out. It's not acting like solenoids anyways.

I guess I'll just have to do some digging into it when I get some time. I am a tech at a toyota dealership and have run it across some of the guys that have been with toyota 20 years ago when these trucks were new, and they just kinda scratch their head like 'that doesn't make any sense' (because it doesn't!). but seems like every time I have time to look at it, it behaves and I can't get it to slip. dammit! Just figured I'd ask around on here and see if any of you folks had run into intermittant slipping like this before. 99% of the time if a tranny slips, it slips all the time. Or it'll be fine cold and slip once it warms up, etc. Never run into it where it slips from start to finish of a 45 minute drive, stop for a coke, get back in and it's perfect again. That kinds leads me towards something on the electrical side that resets with the ignition cycle. Even this morning, went to drop the kids off at school and stop by the grocery store for a couple things. slipped the whole way. ran in and got a gallon of OJ, got back in the truck and was solid as could be. couldn't make it slip if i wanted to. I was in the store literally 4 minutes tops. Definitely not enough time for the ATF to change temp enough to make a difference anyways. I'm really wondering if there's something wacked in the ECU, but like i said when I actually have a little time to look into it, I can't duplicate the problem.

back to the drawing board I guess

4x4runr

not sure if you mentioned this but did you see if you have enough atf in there? i think it takes up about 14 quarts or something like that....

pb4ugotobed

The basics have been covered.