I’m going to pick up some sea foam trans repair and see if that helps. The fluid level is full. The car has around 220,000 miles.
Is sea foam the best stuff to use?
Have you considered the possibility that the torque converter isn’t locking-up when it is supposed to?
When was the last time that the trans fluid and filter were changed?
If it was more than 3 years ago, you might want to start with that service. If you’re lucky with fluid/filter replacement, you won’t have to do a solenoid replacement or other repairs.
I’ve added SeaFoam to transmissions where the TCC solenoid was sticking causing the vehicle to stall when coming to a stop. And it fixed the problem.
Will it work for you?
Don’t know. Give it a try.
Tester
2005 what?
A better description would help. Driveshafts don’t slip, but transmissions do. It would present itself as the engine revving up without actually sending any power to the wheels. If it has been slipping, then the computer “knows” that and it will keep increasing the trans line pressures to reduce the slip. Eventually the pressures will get so high that it shifts hard.
Is the check engine light on? If so, have it scanned for codes and post them. If not, have it scanned anyway, but a typical, generic code reader won’t do. You’ll need something that reads manufacturer specific codes that aren’t part of the OBD2 set.
My guess, your car will soon be in the shop for a transmission rebuild. Trying the ideas above first makes common sense. Be aware however you may eventually find yourself in a situation where the car simply won’t move, so monitor the severity of the symptoms closely.
In the way of an explanation for why this might be happening, the transmission’s inner mechanisms of clutches and bands all require a specified minimum force to work properly. That force comes from highly pressurized hydraulic fluid. The internal seals that are supposed to contain the pressure are probably starting to leak, preventing full pressure from developing, and hence the symptom. The trans rebuild will replace those seals and renew most of the wearing components, then you should be good to go. Your wallet will be a little lighter though !
If you are lucky just replacing the fluid might help, for a while at least. New fluid will contain fresh seal conditioning chemicals. Best of luck.
You can retrieve transmission DTCs with a simple code reader.
https://streetsmarttransmission.com/transmission-diagnostic-trouble-codes/
Tester
Buick Park Avenue.
Some, but not all.
Try pulling a P1811 from a GM with a generic code reader (quite possibly relevant in this case). Won’t work. Ask me how I know…It’s actually why I now own a code reader that will pull any and all codes (or so they say, but I mostly believe them so far).
If it doesn’t affect emissions, then it can easily be “hidden” - as in accessible only to readers that can get manufacturer specific codes.
Not many faults are displayed in the PCM. If the TCM detects a fault or malfunction, the PCM might only show P0700, which indicates a fault was detected by the TCM. A scan tool that allows the user to select individual modules for analysis is needed.
Or does an all modules scan…
I got a can of sea foam and will try that out later this week.
I’ve never changed the fluid or filter. Some say you shouldn’t change the fluid. I may try changing it after I text out the sea foam.
The car has around 220,000 miles. Would the torq converter cause it. To slip on a fast start or up a big hill?
They are stoned. That’s an old wives tale that might have made some sense in the days before electronically controlled transmissions.
The seafoam probably won’t hurt anything, so give it a whirl. Drive a few hundred miles and then drop the pan and do the filter. This only changes a portion of the fluid in any case.
In addition:
Changing your fluid cannot cause any damage by itself, if everything is fine inside the transmission… The issues start to appear when you change the fluid if your clutches are already worn or damaged from use. If you go and replace the fluid after they are already worn out. this can cause slipping…
Look at the color of the fluid, smell the fluid,… And worst case, drop the pan and use a transmission drain pan to catch all the fluid that comes out and then see what all is in the pan… An experienced transmission builder can tell the differences in materials in the bottom of the pan, like friction material, variety of materials, such as bronze, steel-backed babbitt, plastic, nylon, or cast iron, parts of snap-rings etc etc… You can feel the grit from the clutch friction material…
You can put the old fluid right back in it if it looks like it will require a rebuild… Done it many times when a customer didn’t want or have the budget to rebuild the transmission…
What happens is the same friction material that makes the clutch friction disc grip to the steels in the clutch packs (bands are the same way) as it wears off the friction material from the disc mixes with the ATF and causes it to grip… Remove that gritty fluid and put in fresh ATF, now you no longer have (or very little) that grit in the fluid as well as on the clutch fabrics (disc) and now it slips or no longer moves under it’s own power…
Going up a larger hill with the cruise on it would start to jerk the entire car and you had to shut off the cruise and gently get up the hill. I never assumed it was the tranny because otherwise on a flat surface it worked fine.
your transmission could be experiencing issues with worn or damaged components, which might be why you’re feeling slipping or jerking during shifts. Sea Foam Trans Tune can sometimes help if the issues are due to minor varnish or deposits within the transmission, as it helps clean and condition the fluid. However, with 220,000 miles on the car, Sea Foam or any other additive might only provide temporary relief.
Do the same drive but this time when it starts to jerk (while still depressing the gas pedal as normal) use your left foot and tap the brake pedal just enough to turn on the brake light but not slow the car down, see if the jerking goes away… Let me/us know…
Drove it yesterday. About 50 miles. Shifted perfectly from the very start. It still does jerk going up hills in cruise that you have to instantly get it out of cruise control. It does not seem like the tranny is causing the jerk but I don’t really know. Used to think it was something else. The tranny has never had any slipping.
I put the sea foam in a few days ago. I don’t think that would have caused a perfect shifting from the very first second. Maybe the weight in the trunk had something to do with the hard shifting. I had a heavy snowblower in trunk.
So you guys think I should change filter n fluid in a couple hundred miles or so.
Definitely do a transmission fluid snd filter service
I believe your automatic transmission may have been equipped with a reusable pan gasket
If it’s still pliable and in good shape, I’d be inclined to reuse it, versus the cheap gaskets that are usually included with a new filter
Was going to do that brake test but it only started to jerk for a split second then downshifted and went up fine.
My theory is in the past it would keep shifting from highest gear to the lower gear and back and forth. Causing a jerk.
Drove it again today. About 50 miles. Last time I drove it 25 miles then it sat for 8 hours and drove it 25 back home shifted fine. Today drove the 25 miles and after a 5 minute stop drove it back home. On the way home started shifting a bit rough again. Not as bad as the other time.
So perhaps it’s only after it’s been running for so long?
What @davesmopar was probably wondering about was torque converter clutch shudder. @VDCdriver driver brought up a torque converter question in the very first reply. For shudder, the is a “mechanic in a bottle” thing that might help: Instant Shudder Fixx - Lubegard But you wouldn’t want to do that if you don’t KNOW it’s the TCC. (Although it likely wouldn’t hurt anything either).
I’m pretty sure that your car has a 4T65E GM transmission. They were notorious for problems - including hard shifting and torque converter lockup issues. (I had one myself, tho in a GM minivan, and it drove me buggy, and all my local transmission guy would do is shrug and say he’d given up on them and just ordered re-mans.)
Anyway - still no code readings to report? That can help - A LOT. A pan drop and fluid change is not that hard if you have a set of ramps, and some basic tools. I ended up installing a drain plug in my pan to make the fluid drain easier. I also installed some bits from a TransGo shift kit that solved my issues. But without codes, or further checking this or that, you’re shooting in the dark.