It has 98xxx miles on it and the body looks great. Thought itd make a great driver and Id get another 50xxx miles out of it. Ive been working some of the little kinks out of it as Im finding them, but theres one I havent tackled yet.

After driving it a couple times I noticed when the car gets nice and warmed up(say drive it 10 miles, then on the way home from that trip) When going about 40-50mph you slightly hit the gas to accelerate and the car doesnt want to take the gas. I let off the gas and try again and itll usually works then.
I added some fuel injector cleaner and that didnt seem to help.
Ive been suspecting its the O2 sensor because Ive had that be a very similar problem on other cars.(and it happens after the engine is warm, when O2 sensors operate) I will probaly change that. Although the car isnt giving me any check engine light. Also I suspect maybe the catalytic converter is clogged, but again I think that shoudl throw a code because theres a sensor after the cat.
A couple people mentioned that maybe the tranny/torque converter is slipping. Im scared to death that may be the problem. If it was rear wheel drive I woudlnt care, but theres no way Im swapping a tranny from a FWD sedan with sensors everywhere.

Has anyone had a similar problem? To recap: The car hesitates when you hit the gas pedal after warmed up going hwy speeds.

What further diagnosing can I do? I will try to find some shops that can diagnose it for free if it gets worse and I cant figure it out.

Any help is greatly appreciated!

If the TCC won't come out of lockup right away when you put a slight throttle demand on it while cruising, it'll feel kinda flat, and not accelerate well, and if the TCC is bouncing in and out of lockup it'll feel like a slight bucking or lurching.

The speed you describe is about right, that's where you notice it the most. Try driving it in D3 instead of the overdrive range and see if it still does it.

I agree with Jeff. The other test is to unplug the TCC solenoid and see if the problem goes away. IF it does, you have a sticky TCC that's not disengaging quick enough. Try Seafoam or Trans-x trans treatments, they both actually work, and may free up that TCC for you.

Good ideas..
Anyone else with a 3.1 engine have similar problems?

I have another question after reading around the forum..
How can I find out what tranny I have? It says D-3-2-1 on the column. It doesnt have (D) lke th other models. Does that mean this is only a 3spd tranny? I cant really feel it shift and count it. How can I tell if it has overdrive or not?

I have another question after reading around the forum..
How can I find out what tranny I have? It says D-3-2-1 on the column. It doesnt have (D) lke th other models. Does that mean this is only a 3spd tranny? I cant really feel it shift and count it. How can I tell if it has overdrive or not?

No, that's the standard 4 spd. If you start from rolling at 45 mph and downshift one range for each 10 mph or so as it slows, you'll feel each one individually. Don't go through the windshield when you hit -1- :biggrin:

Sometimes a crappy plug wire can almost feel like the TCC issue, as you don't really feel it until the car is cruising in a high gear/low rpm mode. Then the stumbling becomes real noticeable, but since you said it seems draggy trying to accelerate, but clears after letting off the throttle and trying again, I'd lean toward the TCC problem.

You might want to put an ohm meter to the throttle position sensor and sweep it, checking for dropouts in reading, just to rule that out.

02 sensor problems will usually be picked up by the computer pretty quick, and since you have no codes, I'd doubt that. You have two, so if the ECM sees a huge unexpected discrepancy between them, it'll light the MIL.

P.S., like 02 sensors and EGR operation, the TCC only operates once full operating temp is reached.

Well I was driving in OD and after about 30 minutes the car was bucking really bad. I stopped and put it in 3rd gear. The bucking was gone and the car ran great.
So Im glad I found out whats wrong, but Im dissapointed it had to be the transmission.
Theres one big plug that goes to the front of the tranny(facing front of car). According to my wire diagram its one of those wires that controls it. Will I be ok if I just snip that wire? I know itll make my RPMs go up a little, but thats fine for now.
How exactly do I repair the TCC? It doesnt explain how to service the transmission. What is exactly broken?
Thanks for all the help

Is it the switch itself that is most likely malfunctioning? Do I have to remove the transmission just to service the switch?
Ive been doing alot of searching on the web and cant find out how to remedy the problem other than disconnecting it.

Thanks for all the help

To remedy the problem you can either run some TransX or Trans Tune through to see if it'd help. If you don't want it fixed, just run in 3 (or Drive). It'll prevent the converter from locking up, hence what you feel.

If you run some seafome/transx and it doens't take care of it, rip into the side of the case and replace the solenoid is about the only thing you can do it actually fix it. Disconnecting won't 'fix' anything, it'll only eat more gas since the converter isn't locking up, and that's what Drive does.

I have a 99 lumina LTZ, and at times mine would do what yours is doing.
I recently changed the tranny fluid and filter, and I also added LUBEGARD® ATF PROTECTANT. Napa carries it. Think it was about 10 bucks. I did some research on the product, and it seems like a good investment.
Since I changed the fluid a few weeks ago, I have not had any problems with shuddering etc.
Hope this helps
paul

To remedy the problem you can either run some TransX or Trans Tune through to see if it'd help. If you don't want it fixed, just run in 3 (or Drive). It'll prevent the converter from locking up, hence what you feel.

If you run some seafome/transx and it doens't take care of it, rip into the side of the case and replace the solenoid is about the only thing you can do it actually fix it. Disconnecting won't 'fix' anything, it'll only eat more gas since the converter isn't locking up, and that's what Drive does.

So, do I have to remove the transmission to access the solenoid? I can see where the big plug wire connects it goes to more plug wires inside. Can I access it through that hole? How can I get inside the case?

If (3) is the same as disconnecting the wire, theres no reason to do that.

Thanks for all the help!!!!!!

Well, I drove the car around againt today in 3rd gear and it STILL did the problem. So im not sure what to think.
Still does it at about 40-60mph, and I can tell when its getting ready to do it. There will be a vibration/groaning from the drivetrain as its doing it.
Any thoughts?

Any help?? PLEEEAASEE :)

Had autozone run codes.. "No codes returned" :(

Any thoughts on the tranny?
Gettign ready to change fuel filter for fun of it..

[QUOTE=JunkyardLife]It has 98xxx miles on it and the body looks great. Thought itd make a great driver and Id get another 50xxx miles out of it. Ive been working some of the little kinks out of it as Im finding them, but theres one I havent tackled yet.

After driving it a couple times I noticed when the car gets nice and warmed up(say drive it 10 miles, then on the way home from that trip) When going about 40-50mph you slightly hit the gas to accelerate and the car doesnt want to take the gas. I let off the gas and try again and itll usually works then.

I went through the same EXACT problem with a 96 Olds 3.1 I almost GUARANTEE that if you change the module under the coils, the problem will be fixed. (I actually carry a spare and got mine at a Pick A Part wrecking yard.) It is easy to change out, and if you buy one from a yard, you DO NOT need to buy the coils. The modules are 75 to 125 new, so either go eBay and get the whole pack (Usually around 15 plus shipping.) or again, go to a do it yourself yard. Let me know how this pans out!

Thanks for that tip! Maybe Ill give that a shot

Is that TCC lockup behavior driven by manifold vacuum??

Not that Im aware of..

Well, I'm flying blind, here, not having a schematic for the transmission. In the past, intake manifold vacuum has been used to directly control the load-demand shifting of automatic transmissions. Low vacuum meant high load and induced the transmission to downshift. Absent that kind of direct signalling, there has to be another, and I can only conclude that it would be electronic, though even that could be vacuum driven off of another sensor.

Anyone know whether the vacuum system figures into transmission control at all on the Lumina?