Transmission shifting very, very bad

[skregal]

My wife and I were driving to the doctors this morning and the transmission
started shifting really, really bad (GXP).

It would clunk, hammer, collide (try to imagine it) into each gear. It was so
hard that at first I thought someone ran into us, it was that bad.
At the next stoplight my wife put it in park and then back in drive and BAM!!,
it did it also going into drive while not moving. It continued all the way to the doctors
going into every gear.
If I didn't need the Dr. appointment so bad I would have made her pull over.

At the doctors I checked the trans fluid, full and red, just changed about 3 months
ago, BTW.

When we came out about 2 hours later the car drove absolutely fine....perfect.
No SES light ever. No more problems, my wife drove it back to work about 10 more miles,
nothing, shifting smooth as silk.

I called the dealer and they said if there is no light and it isn't still doing it, then it was up
to me if I wanted to spend the $95 fee to look at it. Gee thanks Mr. Dealer.

Any ideas at all??? I wanted to drive this car out-of-town over Memorial day.

[CMNTMXR57]

Most likely the pressure control solenoid. Exact symptoms you mentioned. This is actually common on 4T65E's found in the V6 Bonneville's (and other GM FWD cars it's used in) such as your SSEi, but evidently not common in our 4T80E. I've had this issue with mine and have posted about it in here, asking if others have had the same on these particular transmissions, I only got cricketts in response. So you and I seem to be the only victims. Sounds like something (debris) came loose when you changed the fluid 3 months ago. Did you do a power flush when you did it? That could've definetely jarred something loose, that is getting caught up in the solenoid.

Unless it becomes something that happens everytime you drive it, you probably don't want to know the labor costs involed with replacing the PCS solenoid.

You'll be fine to drive it over the weekend. If it acts up again, just shut it down for a few minutes, then re-start.

[00Beast]

Could possibly try some Seafoam Trans tune in there, then do another drop and fill, leaving the new filter.

Also, his SSEi has a 4T60E-HD, not the 65, being it a 95.

[CMNTMXR57]

Does it matter for the scope of this conversation? It's a transverse 60 series. If we were talking about specific internals of that transmission, then yes, but in the scope of the conversation, pointing out a common problem with one series of transmissions he has in an older car vs. another in this car where the problem lies, it's not.

It's most likely the PCS. You can try the seafoam option, it may work, but my guess is that it will do very little to clean out the solenoid itself. It will (the solenoid) either pass the debris on, and if not and the problem continues, replacement with a revised (Bosch I believe), solenoid is the true avenue of fixes.

[skregal]

A shop did the transmission service. He did some sort of power flush because
the mechanic came out and talked to me about Bonnevilles while it was
"running through it's flush". His words. ???. We also talked about the
proper trans fluid for this car, as there was somewhat of a question at first.


After the fluid change, I noticed the transmission shifted much smoother
from park to drive (or park to reverse). The typical bump (better have a good
foot on the brake) was gone. I didn't notice any change while rolling
and going through the gears, though. That was three months ago, anyway.

I do have a warranty on this car, if you think I should try to pursue this.
I will probably get the GM Dealer runaround, however.

[PRD2BDF]

Also, his SSEi has a 4T60E-HD, not the 65, being it a 95.

I don't know if you know but it's about his GXP, I noticed he put parentheses around GXP and it's in a GXP/Northstar section.

[00Beast]

I understand it's about his GXP, and my first comment was towards it. But, I was correcting what CMNTMXR said that his 95 had a 4T65, which it doesn't. It's a small thing, so whatever.

I would call the dealer and have it scanned for any pending or history codes.

[skregal]

Will the PCS usually store codes if the SES light doesn't come on?
I don't want to spend the $$$$ at the dealer to scan for POSSIBLE codes.

I understand this may be a hard question to answer since only myself
and CMTNMXR seem to have had this issue, but I know that
PCSs can be troublesome in all the bonnie trannys.

[00Beast]

On your extended warranty, would it cover a scanning? If not, go to a parts store that does it for free.

[Archon]

You could very well find code P1811 - long adaptive shift. That will set maximum line pressure which is what causes the rough shifts. Most basic code readers won't see that code.

[skregal]

I have an AutoXray EZ-Scan 6000 but I think your correct that
a code like that needs a more professional scanner. I will
give it a try anyway.

My warranty has a $100 deductible, so I would pay either way.
My warranty has no deductible if I take it back to the dealer
that I bought it from. Oh yeah, that dealer went out of business
Thanks again GM

[Archon]

If it does find it, and you erase the code, you'll likely find that the shifts won't be as harsh. It's a given that the code will come back, though. The only question is how long before it does.

[CincyGXP]

Mine did the sme exact thing about a year ago. Lasted a couple miles, next day it was fine and has been fine since. Wouldnt worry too much about it.

[PontiacFan]

2005 GXP, right at 90k miles & mine has done this a few times over the last year.
Only happens during a start-up & go. Hot or cold. Never after driving for a period of time.
Hi-Pressure Solenoid.
If it happens, stop, shut-off, re-start & go, ..., it's back to normal.

[myfirstbonnie]

My Aeroforce gauge actually picks up the P1811 code.

[CMNTMXR57]

P1811.

ANy extended warranty should pay for any diagnostic service related to the repair. After you pay any deductible of course.

As to transmission damage, yes. But only under prolonged, continued shifting like that. If it was just one trip to the doctors office, you noted it, and then it was fine on the ride home, I wouldn't sweat. It happened to me twice (I posted about it in this section awhile back) and it hasn't happened since.

And now that I said that...

[obis88]

Haven't been on here for quite awhile now. Just read about this shift problems and I have had this hapen to me on several occasions. It seems to happen after I have manually shifted it or when it downshifts when I am passing. When I shut the car off for several minutes and start it back up everything is fine again MOST OF THE TIME....but not always. But if I leave it off for an extended period (such as for the night) the next morning everything is fine. I have gone to the dealer twice about this and they can'y fnd anything wrong. I've had the trans fluid replaced twice since I bought the car new in 2004. The car has 105,000 miles on it and runs fine otherwise. I do drive the car fairly hard when it is safe.

[CMNTMXR57]

If yours is doing it more frequently, I'd look into getting it fixed personally.

[blubyu]

Mine did that just before it took a dump @ 120,000 miles.

[pogo41]

After an overheat condition due to a bad tensioner that ate the waterpump belt (doubt this is related) I to had the "hard shift" and slam from park to drive, after shutting the car down for a few, this seemed to resolve the hard shift and slam issue. Not sure if it will come back soon but changeing out that solenoid sounds well, expensive. Transmission had the power flush at 51k theres now 78k on the car, overall besides, leaking oiler cooler lines, bad wheel bearings, leaking high pressure power steering hose, the car has been relatively reliable, this sudden transmission hicup is concerning me though........wondering if anyone has done the solenoid and what should one expect to pay at or outside the dealership..........