Possible transmission issue

[Merkava_4]

2000 Buick LeSabre with the 3800 V6
Transmission: 4T65E
Mileage: 122,744

I was cruising along on the freeway today and when I go to let my foot off the gas to slow down a little bit, I get this BANG! It's like I ran into a brick wall. And then later on when I'm in town, I go to accelerate from a stop under heavy throttle and I get the same sledge hammer bang I got earlier on the freeway. It feels similar to the feeling I got once when I hit the 108 mph speed limiter. The engine computer either cuts off the ignition, or shuts down the fuel injectors at 108 mph; I don't know which. Other than that, the engine runs fine. I figured I'd post this in case somebody else out there has had a similar issue. No check engine light.

 

[crazyoildude]

Sounds like an engine or trans mount if its not steering related

 

[Brybo86]

try disconnecting the battery for 5 minutes then reconnect it

maybe the ECU has learned some funny fuel management or shifting behaviors and needs to forget them

 

[Merkava_4]

Originally Posted By: crazyoildude
Sounds like an engine or trans mount if its not steering related



I've had a bad transmission mount in that car before; this feels totally different. Instead of a slow heavy clunk when making a left turn at low speed, this sensation is very abrupt with a forceful bang. It feels like running into one off those parking lot curbs, but the car is in motion when the bang occurs. I'm not sure, but I think the engine speed is briefly interrupted when the bang occurs too.

 

[Nick1994]

Those aren't known to be good transmissions in the first place. Go to a local transmission shop and see what they think if you can't find the problem.

I know what you mean with the speed limiter, my 96' Chevy truck had a 100 mph limit, I thought I killed it when I hit 100 mph the first time!

 

[clinebarger]

Scan the PCM for Transmission Codes. Certain codes cause max line pressure causing harsh shifts.

 

[901Memphis]

Your pressure control solenoid is usually the culprit. It gets damaged over time from heat and will command max line pressure. It's a cheap part but unfortunately deep in the transmission so it will eventually lead to a full rebuild if you don't correct it asap.

The transgo 4T65e kit can prolong the clutches but eventually the clutches will wear out from the banging and you will then be slipping and banging.

I have the same exact transmission in my Buick Century... Recently got it replaced by a proper rebuild triple edge unit.

I drove to over two years with banging gears over 20k miles before it finally started to slip.

Be careful if you take it to a transmission shop most of them are dishonest around here they will charge you over $2300 for a rebuild and just change the clutches and slap it back together... These things need lots of care and attention to be done right... Many issues that need addressed that not even get taken care of by so called "professional" shops.

For instance rebuilding a 2000 model 4T65e and using the AC Delco pressure control solenoid will result in the same problems down the road. You will need a borg Warner PCS to correct the issue.

Seriously though email Dave at triple edge, no one else rebuilds these transmissions better.



http://www.tripleedgeperformance.com/sit...blems.html#2712

 

[Revving2Redline]

I dont know what is scarier, trying to find out the tranny problem or trying to find someone not to scam you on a automobile job. I always thought people worked on cars to help people and because they liked cars. Wish Detroit felt like that then maybe their cars wouldnt be in the mess they are in. Hope you get honest answer on whats wrong.

 

[901Memphis]

That's why I ended up letting triple edge build my transmission and let a independent shop install it.

 

[Merkava_4]

901Memphis -- the independent shop that installed your transmission; were they also the people that removed your transmission and shipped it off to Triple Edge?

 

[bbhero]

I just have to say Memphis that you really are AWESOME. Really great to see someone giving a lot of great help to others in circumstances that can easily go bad quickly. Good stuff indeed.

 

[Trav]

How far do you want to go into this yourself? You can do a pressure test on it and check transmission codes.
Clutches, valve body, chain/sprockets, and most other internals can all be done in the car.

 

[901Memphis]

Originally Posted By: Merkava_4
901Memphis -- the independent shop that installed your transmission; were they also the people that removed your transmission and shipped it off to Triple Edge?


Merk, they have cores available at triple edge. They will start building your unit as soon as you pay . You can return your core after you install the rebuilt one.

They will rebuild your core if you want, but it's not really necessary these cores are everywhere.

I opted to eat the core fee and had my mechanic junk the original transmission since it was so far gone I was worried it was full of metal which would make it a non returnable core.

FYI they are pretty busy at triple edge, so it took about 2-3 weeks to get my unit shipped after I paid, they are very busy but totally worth it.

 

[901Memphis]

Originally Posted By: bbhero
I just have to say Memphis that you really are AWESOME. Really great to see someone giving a lot of great help to others in circumstances that can easily go bad quickly. Good stuff indeed.


Thanks bbhero.

Merk, I wanted to clarify something in my previous post. If you don't have money for a whole rebuild the transgo kit will stop the banging and usually get you by with many more years of service. The only problem is that some of it is easily installed with a pan drop except the whole kit installation requires a little more work.

Even just installing the parts of the kit from the pan will help a lot.

Here is a detailed writeup that you can see if you want to tackle it.

http://www.grandprixforums.net/threads/7...tailed-Pictures



The triple edge standard rebuild like the one I have comes standard with the transgo kit already installed along with the sonnax sure cure kit which together are a big improvement over stock. Not to mention the other upgrades that you get...


Refer to this page for mortgage loan information.
http://www.tripleedgeperformance.com/GM_Standard_Replacement.html


I do agree though that you should first get the transmission codes read and make sure it's not something simple instead of the common stuff

 

[Merkava_4]

- 901Memphis,

- Did you buy the 4T65E standard replacement, or did you buy the 4T65E-HPS1 performance upgrade transmission?

- Did they ship it straight to the repair shop?

- What did they charge you for shipping?

 

[HTSS_TR]

Originally Posted By: bbhero
I just have to say Memphis that you really are AWESOME. Really great to see someone giving a lot of great help to others in circumstances that can easily go bad quickly. Good stuff indeed.

Agreed, he is a great guy here.

 

[Merkava_4]

It acted up again tonight why entering the freeway onramp. At about mid throttle while accelerating to 65 mph, the car started bucking violently for a second or two and then smoothed out like nothing happened. I couldn't get it to replicate the issue for rest of the night. I drove up and down the freeway trying to get it to act up again but it never happened. In the meantime, the transmission is shifting fine and it even down shifted while slowing down on the offramp. Weird.

 

[901Memphis]

Here is the information from my email with them earlier this year.

- 4T65E Standard Replacement series rebuild, includes reman torque converter $1674.95

- 4T65E core fee, standard early style $250

- Freight shipping one-way to a business address in your area $175, or $350 round trip if sending core back

Our current rebuild turnaround time for this type of rebuild is about 2 weeks plus shipping time once orders are placed.




I had them ship the transmission directly to my mechanic. I think they use RL carriers or something like that.

I got the standard rebuild, Dave from triple edge said that going with the higher units in a stock non supercharged application could result in overly firm shifts where they aren't wanted or needed. They are build with different tuning for higher output vehicles. That's why they ask for a detailed build sheet when getting a custom transmission so they can baseline tune for your horsepower output.

 

[901Memphis]

The bucking is weird not a known transmission problem. I have heard of some engine issues mimicking transmission problems.

Classic symptoms of transmission issues in these vehicles would be harsh down shifts after getting up to temperature and making a certain amount of shifts with shift times exceeding the 0.5 second limit tripping the max adapt code until the vehicle is shut off for some time.

 

[Trav]

Originally Posted By: Merkava_4
It acted up again tonight why entering the freeway onramp. At about mid throttle while accelerating to 65 mph, the car started bucking violently for a second or two and then smoothed out like nothing happened. I couldn't get it to replicate the issue for rest of the night. I drove up and down the freeway trying to get it to act up again but it never happened. In the meantime, the transmission is shifting fine and it even down shifted while slowing down on the offramp. Weird.


Its not uncommon for the ignition module to fail on these causing those sorts of symptoms. The heat sink compound deteriorates over time on the iron bracket and it overheats causing intermittent problems.
Its just one of many possibilities but its often overlooked.