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RPM question


cubsfan24

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When I am on the interstate in my 3100 Lumina I can be going lets say 70mph @ ~2400 rpm. Say I press the accelerator just a little harder and the rpm's shoot up about 200-300 rpm's and drop back down after a second or two. It usually does this when I am going a constant speed and have to slow down a tad because someone cuts in front of me and I have to slow down. When I press the gas very slowly to regain speed it will surge for a couple seconds. Just something I have been wondering about. Thanks

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Hmmm, well I am starting to get into my "I want to drive like a grandma to save gas mode" because gas is going up again. I try to slowly accelerate and not mash the gas (all the time :lol:) I just find it weird how I press the gas a hair more and it will do this. Could the TCC be going bad?

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possible, but not likely... at 70MPH a 3100 is working fairly hard( at least the TCC is) and to prevent it from burning up, it has to disconnect when under high load. i don't know what the threshold is for it, so i couldn't tell you if its disconnecting too early or not. that and a datalog would be necessary to see TPS percentage when it does disconnect.

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Ok, I was just wondering today coming back from school. It has been doing this since I got the car so I guess if it ain't broke hope it doesn't break :lol: IIRC it does it more when I am doing 65+ than it does when I am going <65. I guess I never paid attention to the speeds when this happens. I will try to get it to do this when I am going slower.

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with my 95 monte, it prevented lockup of the TCC until 45MPH, at which point i can only push so far onto the pedal before it would kick out. entirely normal. your lumina being obd2, i couldn't tell you when its supposed to kick out.

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Now I was going to say because I have a lumina with a 3100 I do have an issue with the TCC solenoid locking and unlocking. It will happen between 45mph and 55mph. It horribly stutter and it acts as if unsure to change gears when I slowly increase. I am getting used to when it does it right when after two seconds the rpm drops I can hear the car may a low growl noise and I will lightly stomp it for the TCC solenoid to disengage so that It doesnt freak out. I dont have any codes but its sometimes annoying.

 

If you dont have the mentioned problem above, then you have a good working transmission. :lol:

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gas is going up again?

 

It has gone up to $2.10 a couple times here. It isn't too bad right now but it is going to go up this summer. Two tanks ago I went the speed limit (or 5 over) and took it easy and got nearly 31mpg. However this tank I only got 25mpg because I got stuck in stop-n-go traffic twice for two miles (thanks to cops pulling people over during morning rush hour) and drove her harder. This is a big difference when gas goes back up to $4+ a gallon. Oh boy I can't wait.

 

Ya, other than the slightly rough-ish 1st to 2nd shift sometimes when the tranny is warm, the transmission seems to be working good.

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VERY NORMAL. the TCC is supposed to engage at 47 mph, under lighter throttle conditions.

 

The tcc will disengage if you slow to 46 mph, if you touch the brake pedal, if you increase throttle enough to have the PCM disengage it, or if the transmission is malfunctioning(mine keeps doing so as it overheats).

 

That said, the functioning described above by most of you is normal. if you are getting mild studdering and surging at lower TCC applied speeds, you most likely have some tune-up issue with your car: you aren't producing enough power for the situation, and you are lugging the motor. (a weak fuel pump caused this for me)

 

Also, I advise everyone with e 4t60e to add a transmission cooler... odder behavior from the transmission can be accounted for by too much heat. these trannys NEED more cooling that stock.

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funny, i'm up to 186XXX miles with no cooler but i did buy one a few years ago, but never had the time to put it on. that and i watch the temp coming from the tranny fluid sensor... whats a normal temp for tranny fluid? i know with oil you don't want it above 250F for conventinal and like 275/285 for synthetic. i never find reliable info about tranny fluid though

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funny, i'm up to 186XXX miles with no cooler but i did buy one a few years ago, but never had the time to put it on. that and i watch the temp coming from the tranny fluid sensor... whats a normal temp for tranny fluid? i know with oil you don't want it above 250F for conventinal and like 275/285 for synthetic. i never find reliable info about tranny fluid though

details? what reading do you get?

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the cooler the better, would be ideal to keep both tranny fluid and engine oil at roughly the same as the engine coolant with a cooler on both you can achieve this no problem. all transmissions should have a cooler (not a shared unit with engine coolant) especially if you have a lead foot :burnout:

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thats about 56MPH.... its a bit late, but depending on how far your foot is into the throttle, it could be normal.

 

vehicle info?

 

92 lumina 3.1

 

welp i forgot that my speedo is about 10km/h off (too fast) so really its engaging at 80.

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VERY NORMAL. the TCC is supposed to engage at 47 mph, under lighter throttle conditions.

 

The tcc will disengage if you slow to 46 mph, if you touch the brake pedal, if you increase throttle enough to have the PCM disengage it, or if the transmission is malfunctioning(mine keeps doing so as it overheats).

 

That said, the functioning described above by most of you is normal. if you are getting mild studdering and surging at lower TCC applied speeds, you most likely have some tune-up issue with your car: you aren't producing enough power for the situation, and you are lugging the motor. (a weak fuel pump caused this for me)

 

Also, I advise everyone with e 4t60e to add a transmission cooler... odder behavior from the transmission can be accounted for by too much heat. these trannys NEED more cooling that stock.

 

i've gotten mine to engage as early as 38-40mph, and disengage around 35. that is all under very light throttle.

 

you are right, ken, the trannys do need more cooling. my car's got 151k miles on it and tranny is doing fine, even with some heavy driving, so i don't think im gonna put a cooler on.

 

At 70, my 3100 Luminas are at 2300-2400 rpms. If you feather the gas, it does as you are describing. Your car sounds normal to me.

 

mine does the same. sounds normal to me too.

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you are getting close to the milage where most of these cars start having tranny issues, coolers are cheap transmissions are not!

 

i got a fair bit of miles on mine, maybe i should buy one too...

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"All" i repeat "ALL" automatic transmissions should have a cooler no matter how you drive or what conditions you drive in. in the long run it will not only keep your tranny cooler but also encourage your engine to be easier to cool. the factory setup requires the radiator to cool both the engine and tranny

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yes.

 

remember 91-93 3.4 dohc cars all had coolers.

So did some 91-93 3800 cars.

So did some 3.1 mpfi cars... my 91 international has one (with a 3.1 mpfi, plus it has an oil cooler) as well as several of the 2.8/3.1 internationals I have looked at.

 

They wouldn't be there if there was no benefit to having them.

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