1990lumina Posted November 3, 2004 Report Share Posted November 3, 2004 Hey, this started about a month ago but I thought it was my driving habits, however I've changed the driving habirs numberous times and I still can't figure this out. Here's what happens: 1990 Lumina 3.1V6 4T60 Transmisson I am driving along at the speed of traffic. I've accelerated to around 60km/h and I'm coasting along and I'm pretty sure the transmission has gotten into 3rd gear already? My speed is decreasing a bit so I just touch the gas a slight bit when this happens: the transmission seems like it is either wanting to downshift and upshifts right away or it falls out of gear and then goes back in somehow? This also happens when I take a corner at a fair bit of speed, try and accelerate after the corner and it will do the exact same thing, however, once it figures out which gear to use or whatever it is doing it seems to shift good, holds rpm when manually downshifting, doesn't slip when getting on the gas pedal, only when tocuhing the gas after coasting or around 45-50km/h does this seem to happen. Another thing, my car doesn't start in neutral, only in park... so coould this be possibily related or a safety feature, or just another problem all together. However, the first problem I'm having I think is more important. Does anyone have any insight for me? Is my transmission on the way out; I sure hope not but am prepared for the worst. Thanks everyone!!! - Jeff L. Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted November 3, 2004 Report Share Posted November 3, 2004 Are you absolutely positive it has the correct amount of fluid in it? Quote Link to comment Share on other sites More sharing options...
gpse_97 Posted November 3, 2004 Report Share Posted November 3, 2004 maybe its just the TCC locking up? TCC=Torque Convertor Clutch) on my '92 4T60-E it locks up around 70km/h Quote Link to comment Share on other sites More sharing options...
1990lumina Posted November 3, 2004 Author Report Share Posted November 3, 2004 Sorry, Yes I should have mentioned... I checked the tranny fluid. It is a nice red color, and and seems to be full on the dipstick. If it matters at all the transmission pan gaskets and all were redone when my grandma still owned the car this summer by GM. Would the TCC lockup right as I apply the gas, or would it be unlocking when I pres the gas pedal as I'm slowing down? This only happens after coasting for awhile then applying the gas. I know usually the TCC lockuping up feeling kid of like another shift, but this feels like it doesn't know what to do so it goe into neutral then back into the same gear it was already in?? - Jeff L. Quote Link to comment Share on other sites More sharing options...
THe_DeTAiL3R Posted November 3, 2004 Report Share Posted November 3, 2004 Vacuum leak? If its sucking in air then it's not gonna shift... Maybe check the vacuum modulator too. Quote Link to comment Share on other sites More sharing options...
pitzel Posted November 3, 2004 Report Share Posted November 3, 2004 Hmmm. Sounds remarkably similar to how mine behaves; does your Euro have a tachometer at all to prove this? Also, my 4T60 behaves somewhat differently warmed up, as opposed to cold, so maybe yours is getting the cold-weather blues, eh? Can you verify this behaviour continues to exist once the car and transmission are completely warmed up? Quote Link to comment Share on other sites More sharing options...
1990lumina Posted November 3, 2004 Author Report Share Posted November 3, 2004 Pitzel - Yes I have a tach. When this happens it usually revs around 1200 while coasting then when I touch the gas it will do that thing it does and revs to to 2500 then immediately back down to about 1500 and rises with the vehicle's speed. Mine seems to be the opposite of your's where mine starts doing this once it has warmed up. When I'm in stop and go traffic I notice it alot more, while in stop and go traffic my engnine usually runs a little warmer as the fans don't cut in to about half of the temperaturee guage. C-BAD - How do I check for vacuum leaks? I have to admit I'm a bit of a n00b when it comes to these types of transmissions. Anyother suggestions?? Tranny only has 140,000km on it (about 86,000miles) - Jeff L. Quote Link to comment Share on other sites More sharing options...
Regal_GS_1989 Posted November 3, 2004 Report Share Posted November 3, 2004 Sounds exactly like what mine does. Except mine does that around 30-35 km/h. I have changed the fluid and it still made no difference. Mine feels like the TCC is unlocking too much, then locking back up. BTW, mine only does it if i accelerate hard from 30-40 km/h, so i have accustomed myself to being a little more gentle in accelerating from those speeds. Quote Link to comment Share on other sites More sharing options...
maybe2fast Posted November 3, 2004 Report Share Posted November 3, 2004 check the vacuum modultor (super easy to replace) drivers side, in the front of the trans, little vacuum line running from it to the TB Quote Link to comment Share on other sites More sharing options...
paulo57509 Posted November 3, 2004 Report Share Posted November 3, 2004 My '92 Lumina acts like this too. Adjusting the transmission shift cable helps, but I find that it takes a real heavy foot to get the transmission to downshift. Quote Link to comment Share on other sites More sharing options...
WhiteOut Posted November 4, 2004 Report Share Posted November 4, 2004 Its normal behavior for a 90' or previous 4T60. They have trouble deciding between 3rd and 4th gears when coasting between 50-70mph. If you've got a tach you can watch it bounce back and forth. Basically it just means the trans is getting old, changing the fluid will help to some extent, but expect the behavior to return shortly. As the problem gets worse you can expect the trans to start acting in the same way while going up inclines in overdrive at 60-70mph. In short there's not a whole lot you can do besides live with the problem or replace the transmission. Quote Link to comment Share on other sites More sharing options...
pitzel Posted November 4, 2004 Report Share Posted November 4, 2004 Its normal behavior for a 90' or previous 4T60. They have trouble deciding between 3rd and 4th gears when coasting between 50-70mph. If you've got a tach you can watch it bounce back and forth. Basically it just means the trans is getting old, changing the fluid will help to some extent, but expect the behavior to return shortly. As the problem gets worse you can expect the trans to start acting in the same way while going up inclines in overdrive at 60-70mph. In short there's not a whole lot you can do besides live with the problem or replace the transmission. Interesting; I drove to Regina one afternoon with somewhat of a tailwind, at roughly 50mph, and the car exhibited the same behaviour; couldn't decide which gear, 3rd or 4th, to be in. I'm assuming that since 50mph with a fairly strong and gusty tailwind barely would be essentially loading and unloading the engine, causing the transmission to lose gear stability as it moves from a power-on to a coasting regime. Needless to say, I barely burned any fuel for the hour trip. Quote Link to comment Share on other sites More sharing options...
1990lumina Posted November 4, 2004 Author Report Share Posted November 4, 2004 I'll probably just live with, as long as other than changing the fluid (checked it today, doesn't smell burnt and is red and full up) nothing can be done to fix it, or help it I'll just drive it till one day and it won't go anywhere. I'll also check that vacuum modulator, but if that checks out I'll just drive it and live with it as WhiteOut had said. If it can get me through school... 1.5 more years I'll be happy as unfortunately if you have a car that is newer and is in good shape someone vandalizes it or worse, (and thats the good side of town, not to stereotype because our eastside isn't as nice as it once was). Anyway thanks for all the help guys! - Jeff L. Quote Link to comment Share on other sites More sharing options...
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