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Slipping tranny? Help!

3K views 18 replies 7 participants last post by  transtech520 
#1 ·
Hey all,

A week or so ago I came out of a parking lot (making a left) on to a main road and as I step on the gas it felt as if the car was in neutral. I immediately let off the gas to check that IT was in fact in drive and when I get back on the gas it was fine.

Well today I was doing the exact same thing (making a left out of a parking lot) and this time I was in a hurry as traffic was coming. I step on it and it revs up as if it was in neutral (but still moves me slowly into the road), before I have time to look down it locks up and tires start spinning kicks out sideways and I'm hauling ass.

Tranny does have the Jmod done by a professional 4-5 years ago. I just dropped the tranny this summer to install an upgraded Mark 8 torque converter by Alan. She has 181k miles on her. The current tune sets shift points at 5700 rpm.

Opinions? Options? I just spent $5k on school this semester. I really hope she doesn't need a new trans or she'll be sitting for a while... :(

Thanks!
 
#4 ·
The way those pickup filters are designed with that little tube makes me find it hard to believe it was starving for fluid!

Low fluid IS a good place to start, however. Hopefully that fixes it!

I've pulled a pan on a 4R70W that the filter had come loose where it plugged in to the valve body (easy fix).
I've also seen one leak between the plates - do you know what kind of pressure you're running?
 
#5 ·
Checking the trannys fluid is more of a pain than I remember. The dip stick is impossible to read and I'm afraid to add too much fluid.

Rick, I've never checked the pressure on a transmission before. Can I do it without jacking the car too far off the ground? I'm at school and my real jack stands are at home. My buddy has a pair of little ones. I'll try looking that up online.
 
#6 ·
If I'm not mistaken, if you know someone with a good OBD-II scanner, you can read it through the OBD-II (I'm not sure if trans fluid pressure can be read on our year cars - I know on newer model vehicles that parameter can be read).

If not, I'm sure a good tranny shop would have some kind of hookup to put a gauge inline or know what port to check on the tranny itself.

I'm just thinking on where I would check; maybe someone here more experienced with these trannys can give better advice.....

Oh, and what do you mean you can't read your tranny fluid dipstick? You want me to send you another one??? :eek:
 
#7 ·
Ah ok. I have had that done before but they employee wanted to take the car into the shop and pull the trans out to service it. I got my butt out of there. Yes my dip stick defies the laws of physics, one minute its over full the next minute its not even touching. :bangwall:

When my dip stick started reading consistently, I found the fluid was not touching the end at all. I added about 3/4s of a quart of tranny fluid and I think its back to where its supposed to be.. I'll check it again tomorrow. Seems to run better already. We shall see..

I've had a couple buddies and my girlfriends dad (pretty knowledgable about cars) swear by this Dr.Transmission additive they sell at auto part stores. Only $9 bucks, figure I'll try it if nothing else works.. Anyone tried it out?
 
#8 ·
You talking about that Lubegard stuff that comes it a bottle like this?


Yes, I've used it and it does work. Seems to me that company makes different color bottles that do different things.
One is a Merc V additive, one is a friction modifier, one's a protectant, etc, etc.

IIRC, there are Red, Green, & Black bottles.....
 
#9 ·
There is a commanded TV pressure PID but there's no actual pressure sensor in the valve body. Without using a line tap and gauge there's no way to see what the difference in commanded and actual pressures is.
 
#10 ·
I was thinking that, too - but I was trying not to over-complicate things...
 
#12 · (Edited)
Update - different problem maybe transmission?

Noticed something new today when I was on the highway..

At 70ish mph I stepped on it and it downs shifts to 3rd and right as I'm hitting 85ish (the rpm tach is reaching 3800 rpm) the tach stops and drops for a split second and then kicks back up and keeps going up like normal.

I was really confused so I tried a couple more times and it kept doing it. Exaclty at the same spot. I tried it in first and second gear too and it does not do it and all. Only in 3rd gear at 3800ish rpm. Does this sound like a slipping transmission? Or a tach problem? What can I do for steps to diagnose and fix this? Thanks guys

Edit: fluid is at the right level. I do have to add some here and there to keep it up.
 
#13 ·
Maybe it's lockup?
 
#15 ·
Are there physical signs there's something going on? Do you feel anything?

An XCal2 with livelink would prove most useful here.
 
#17 ·
Not that I can tell. No bad vibrations or noises. Dangit I never bought that damn xcal. No one wants to sell one for lower than $190. If I did buy one and down load livelink could it still give me readings before I've bought an emailed tune right?

Maybe I can take a video of it today..
 
#18 ·
Correct. You don't need an aftermarket tune to data log.
 
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