Transmission shift problems and noi

2001 PONTIAC BONNEVILLE
145,000 MILES • 6 CYL • FWD • AUTOMATIC
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2001SSEIDAVISCA
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I have noticed for the past year when I drive my car for usually more than 20 minuutes in city driving the transmission does hard shifts and either is moaning or the supercharger on it is moaning. Stop and go traffic on the freeway can do it too. Just as quickly as it shows up, if I stop for 5 minutes it can go away and some days it doesnt do it at all.

The transmission has been serviced regularly.

Is this the pressure control valve? Internal clutch? Fluid issues? or what
May 24, 2010 at 1:05 AM
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MERLIN2021
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There are several tech bulletins on your transmission, but most refer to certain codes being set, is the service engine soon light on? If yes go to Autozone, they read the codes free, post all found here. Freeze frame data too if you can.

https://www.2carpros.com/articles/automatic-transmission-problems

This guide can help us fix it
May 28, 2010 at 12:34 PM
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DANIEL3SIMONS
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Well seems like there is no power anymore when step on the gas to get to speed on the highway, the car just has no power and slowing gains speed, also sometimes does gain speed and when it did I keep the pedal down and it redlined real bad, also downshift going up hills? Thank you for your time.
Apr 24, 2020 at 6:08 PM (Merged)
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JACOBANDNICKOLAS
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Does it feel like the transmission is shifting through the gears or is it staying on one gear? Is the transmission fluid clean and full? Has the check engine light come on?
Apr 24, 2020 at 6:08 PM (Merged)
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DANIEL3SIMONS
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Its shifting through all the gears and at that its smooth too, also the fluid is a little over full when checked it while car was running, and fluid don't smell burnt but I do not know when it has been changed
Apr 24, 2020 at 6:08 PM (Merged)
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JACOBANDNICKOLAS
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No check engine light?
Apr 24, 2020 at 6:08 PM (Merged)
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DANIEL3SIMONS
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No check engine light.
Apr 24, 2020 at 6:08 PM (Merged)
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JACOBANDNICKOLAS
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Without the check engine light, it becomes a guessing game. I hate to say it, but it is nearly impossible for me to diagnose this type of problem without being there. Is there anyone you trust that could just listen to what it is doing?
Apr 24, 2020 at 6:08 PM (Merged)
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DIESEL ADDICT24
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My transmission didn't show any sign of slipping and now it won't go into any gear. What could be wrong?
Apr 24, 2020 at 6:08 PM (Merged)
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CADIEMAN
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when you shifting it is the selector on the transmission turning?
Apr 24, 2020 at 6:08 PM (Merged)
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DIESEL ADDICT24
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The linkage on the transmission turns but it won't go into gear. Could it be the neutral switch on the transmission?
Apr 24, 2020 at 6:08 PM (Merged)
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CADIEMAN
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it will need to be checked at a transmission shop.
Apr 24, 2020 at 6:08 PM (Merged)
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JEFF 2004
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my pontiac bonneville se,i had fuel pump changed,fuel pressure were 15lbs mechanic say it suppose to be about 50lbs.now after installing new pump auto trans will not change gears.it seems like it is taking off in over drive,you have to really press on gas pedal to make car move at all.it will change gears only once if you manual shift from low to 2nd at about 35 mph.trans were rebuilt 6 months ago.everything were operating find until i had fuel pump changed.help me please.
Apr 24, 2020 at 6:09 PM (Merged)
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SATURNTECH9
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I don't see how the fuel pump has anything to do with the transmission.Have you checked for codes in the computer yet?Also checked the transmission fluid level and condition of it yet?
Apr 24, 2020 at 6:09 PM (Merged)
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PEEWEE35
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i can start my car and it will go in to gear fine untill it gets warmed then with it in drive it will just rev up when i hit the gas
Apr 24, 2020 at 6:09 PM (Merged)
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CARADIODOC
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Those symptoms could be related to overfilling the transmission, but the first question is why did you have to add transmission fluid in the first place? If there's a leak, low fluid level will allow the pump to draw up air instead of fluid. If the level is excessively high, rotating members will whip up the fluid and introduce air into it. Since air compresses, the aerated fluid won't be able to put pressure on the clutch packs to apply them. That air in itself will not hurt anything. It's the clutch pack slippage from continuing to try to drive it that way that will do the damage.

Address the fluid level issue, then allow it to sit a little while for the air bubbles to work their way out of the fluid.

Also be sure you're following proper procedures when checking the fluid level. The engine must be warmed up and idling in neutral or park after briefly running the shift lever through all the ranges. If you try to check the level with the engine off, the fluid level will appear to be too high.
Apr 24, 2020 at 6:09 PM (Merged)
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GARY BROWNING
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Have a difficult time shifting into gear, as though the linkage is not quite right. Maybe missing a part of some kind?
Apr 24, 2020 at 6:09 PM (Merged)
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CARADIODOC
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If the shift lever is hard to move, but it does go to all the gears, suspect the cable is fraying at one end and is becoming stuck in the casing. You can verify that by disconnecting it under the hood on the transmission. Now, if the lever still moves with too much difficulty, replace the cable. If it moves very freely, work the lever on the transmission to see if there is a problem there. Something binding inside the transmission would be much less common.
Apr 24, 2020 at 6:09 PM (Merged)
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DJSCUZZ
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My quiestion concerns my transmission. Whenever I accelerate rapidly from a dead stop or after only going a 5 - 15 miles per hour, like when trying to pass someone going far too slow, my car will not want to shift out of first gear. The service engine soon light will come on and I'll have to slow down to 5 - 15 miles per hour again for a couple of seconds before it will shift out of first gear. The other thing that happens is that it will not go into overdrive until the service engine soon light goes off. The service engine soon light, overdrive problem usually lasts for half a day to a full day. But now it's been more than a day and my car still will not shift into overdrive. Please help.
Apr 24, 2020 at 6:09 PM (Merged)
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MASTERTECHTIM
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usually the not shifting out of first gear when passing is actually caused by a clogged fuel filter. yes a clogged fuel filter. the check engine light will probably be code 44 which is lean exhaust caused by the fuel filter. hope this helps
Apr 24, 2020 at 6:09 PM (Merged)
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DJSCUZZ
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Thanks for trying to help mastermechanictim. I changed my fuel filter about 2 months ago and it had this problem before the filter change and still after the filter change, so that eliminates the possibility of a fuel filter problem. My dad, who was a master mechanic back in the 80's, said it could possibly be a vacuum problem. If anyone else has some advice as to what it could be, that would be appreciiated. Thanks once again for responding mastermechanictim.
Apr 24, 2020 at 6:09 PM (Merged)
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MASTERTECHTIM
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there is a vacuum modulator on the front of the transmission if you look straight down when the hood is open, although not common to fail it is a possibility. check to see if there is ported vacuum at the valve or check to see if the vacuum line came disconnected. also if the vacuum line is really soft and bloated looking this usually means the modulator valves diaphram is leaking and this too could cause your problem.
Apr 24, 2020 at 6:09 PM (Merged)
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DJSCUZZ
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Thanks for trying to help mastertechtim. I actually ended up taking my car in and had them check the trouble code that my cars computer was giving. It turned out that my throttle positioning sensor was bad. It was putting my car into failsafe. This of course is why my car wouldn't shift into overdrive. Everything seems to be working fine now. Thanks once again for trying to help.
Apr 24, 2020 at 6:09 PM (Merged)
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KASEKENNY
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The most common cause of sudden harsh shifting while driving or after it is warm is normally a sensor issue. There is a chance that there is a fluid issue but if operation returns to normal due to a key cycle or after it sits then this points to a sensor is not reading properly that would effect transmission operation. Clearly there are numerous sensors that could effect it but the most common one is the throttle position sensor.

The reason for this is the engine and transmission control module rely on knowing what the throttle input is from the driver so it can match the air/fuel ratio and know if it needs to downshift or upshift to meet the demand.

I attached the info needed to diagnose this issue. You can also monitor TPS voltage as you depress the throttle. The voltage change should be smooth and no jump erratically. If it is then the control module is getting erratic voltage as well.

Let us know if there are questions. Thanks
Apr 25, 2020 at 1:35 PM