TCC issues :(

[Dancing Bear]

I'll keep it short for brevity purposes lol

- Car has 116K, 02 Pontiac Grand Prix GTP

When I first purchased car, I noticed there was an issue with premature TC lockup when cold. As soon as car reached ~30mph, the torque converter would lock up and RPM's would dive sharply, sometimes the "shudder" would occur that I've read about. As I drove and the car reached operating temp, it would get smoother and smoother until it seemed to act normally at all times. Car shifts through gears normally and transmission has no other noticable symptoms of issues

- Changed tranny fluid, filter and installed Transgo @ 115k

Fluid was pretty brown, and smelled a little burnt, but there was not an abnormal amount of clutch material in the pan. Refilled using Dex IV and 1 bottle of lucas tranny "fix". Torque converter lockup still feels like an extra shift when cold, but I rarely experience the "shudder" that was occuring before. Lockup still occurs around 30mph, which from what i've read is still too early as it is supposed to be around 45mph. Shifting seems perfect. I'm stumped as to why this issue goes away when the car has reached operating temp, as I've read don't almost all tranny issues in these cars get worse as the temps rise?

A little backround on what I believe could be causing these issues:

Bad right front wheel bearing (had the ABS code pulled for it)
TCC solenoid maybe?

*EDIT*: I've been doing some research deep into the main transmission thread... apparently the computer can take up to 200-300 miles to relearn lockup and shift patterns after the battery has been disconnected. Since I've owned the car, I've had the battery disconnected while installing audio gear and other mods numerous times, and havent driven the car that much. Maybe this has something to do with it?

I'm kinda stumped here, and I'm curious on how i might be able to fix this issue, or how long the transmission will last. As I said above, I don't have any other issues other than this one.

Thank you gentlemen for your help!

[Dancing Bear]

Bump for interest ... Bill? Scotty?

[idrivejunk]

Lockup still occurs around 30mph

How are you determining that lockup occurs?

I don't know crap about transmissions... but I'm here.

If your old fluid had a burnt smell its toast. How long until catastrophic failure is anyone's guess. At the worst time would be my guess. In my experience, you are at or near the end of service life on that trans with those miles. There will be at least one wear area thats WAY out of spec. A trans shop can hook up a computer and take it for a spin then tell you if the internal solenoids work properly but thats about it. A rebuild will likely be suggested as you probably know. Do it as soon as possible and maybe not have to replace EVERY part, or drive gently and save up for a full overhaul. Just my .02, and I don't think a wheel bearing can cause this. A bad differential sounds just like a wheel bearing though. My GT's sounded like a box of rocks at 117K.

[CrazyGuy03]

Interesting because lockup shouldn't occur until a certain temp is reached ...

[theaceofspades]

Interesting because lockup shouldn't occur until a certain temp is reached ...

Yeah that temp is a very low 78 degrees often your trans is At that temp in under 10 min of driven even on cold days


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[CrazyGuy03]

depending on where you live , time of season and day, a short trip may never reach that temp

[theaceofspades]

depending on where you live , time of season and day, a short trip may never reach that temp

It was -15 out and my car with stock cooler hit that temp very quickly. I did remote start it once with the cycle.


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[CrazyGuy03]

ok..... Lol

[Dancing Bear]

How are you determining that lockup occurs?

I'm right there with ya... I don't know much about transmissions either. I can feel the shifts pretty clearly, and I determine if its locking up or not by pressing on the brake. I can accelerate around 30, feel the lockup occur and if I press the brake it will unlock. it's because of my inexperience with transmissions that this statement may seem naïve, but if it's shifting fine and isn't slipping/slamming into gear, couldn't I just have them replace the solenoid if its at fault?

And I had the codes scanned for the wheel bearing yesterday.. it came back as the RF wheel speed sensor.
Here's my hypothesis ... but first I must ask who knows how the computer determines torque converter lockup conditions? Like, how does the car decide when to lock or unlock it?

My theory is this ... if the computer needs to see a certain parameter met for TC lockup, if its based on speed maybe it is rapidly locking and unlocking because of a bad signal from the speed sensor? I've noticed on the HUD that sometimes the speed will jump around ~2-3mph erratically and randomly.

One variable that supports this hypothesis is that the shuddering lockup condition happens most often, if not exclusively under very light throttle conditions when the speed is slowly rising. Under moderate to heavy load the converter engages normally with no shudder.

I know like Junk said, the fluid is burnt and the transmission is most likely on borrowed time, but I'm still curious what you guys think. Funds are super tight for me at this moment, so I'm trying to do my due diligence before I pull the trigger on any repairs/diag time. Thank you guys very much for helping so far!