Buick 4T65E hard shift *LONG*

[rshaw125]

Yet another Update.
I had a scanner plugged into the car. The scanner ran a battery of diagnostic tests. No codes. Then they drove the car with the scanner plugged in. Recorded 3 'data streams'. Still no codes. Everything checked out. The only error was 1-2 shift took too long. Each of the 3 recorded data streams resulted in the same 1-2 shift took too long.

Any ideas??
Thanks.

 

[demarpaint]

Originally Posted By: rshaw125
Yet another Update.
I had a scanner plugged into the car. The scanner ran a battery of diagnostic tests. No codes. Then they drove the car with the scanner plugged in. Recorded 3 'data streams'. Still no codes. Everything checked out. The only error was 1-2 shift took too long. Each of the 3 recorded data streams resulted in the same 1-2 shift took too long.

Any ideas??
Thanks.



The delayed 1-2 shift didn't trigger a transmission code? It won't show up in the form of a CEL, but the scan tool will show the transmission code IIRC.

Hopefully Trav sees this and weighs in.

 

[Trav]

Surprised this didn't cause a P1811 code. Do you have any shift time and line pressure data?
If the accumulator shift kit doesn't "fix" this it is usually a boost valve or input clutch piston seal issue.

Both are a PITA to do, the boost valve bore gets scored and hangs the valve causing erratic operation. The leaky piston seal doesn't allow enough pressure build up no matter if the kit is installed or not.

The other problem could be the MAF sensor and although this is engine related a dirty or slightly malfunctioning MAF can cause the ECM to command a lower pressure.
It may or may not cause a CEL or code to be set until the MAF completely fails.

Start with giving the MAF a good cleaning with MAF cleaner, these can also be damaged when cleaning the throttle body (if the MAF is in the body like many 3800) and go flakey without causing a code.
I have changed many of these in this engine as a last ditch effort and it has worked numerous times.

Never use a reman MAF, even the best brands have a miserable out of the box or soon after failure rate.

Edit: I don't mean to sound like a broken record but everything you say has me thinking even more it could be something like the darn MAF.
It isn't slamming hard into gear and free revving which is pointing me there.
It may well not be, just call it a feeling. I wish i could get my hands on this for an hour.

 

[rshaw125]

I cleaned the MAF with the proper spray cleaner. Also the throttle body. This was about 3 weeks ago.

Next? I think the scanner used maybe could not read the enhanced OBD codes. Does this sound crazy?

From talking to Dave at Triple Edge and research it does appear that I have a bad valve in the valvebody. Which one or ones?

Looking at the Sonnax site there are several kits to repair the valves. Wish I had known this while it was apart.
Another scan is in order.
Thanks for the replies.

 

[Trav]

The boost valve with sleeve is the usual culprit.

http://shop.tripleedgeperformance.com/Sonnax-4T65E-Boost-Valve-and-Sleeve-Kit-84754-30K.htm

This guy did a nice pictorial.

http://pontiacbonnevilleclub.com/forum/viewtopic.php?f=8&t=1483

 

[rshaw125]

Looks like it's new transmission time. I had the car scanned again for generic and Enhanced OBD codes. Interesting setup. Bluetooth adapter on the OBD port and the guy used his laptop to run a professional software package. No codes.

I am going to add a bottle or two of Lubegard red. Drive it until it grenades or I have the money to buy a rebuilt/upgraded transmission. Won't be cheap but I probably could not even sell it the way it drives.

 

[bxd20]

Sorry to bump an older thread, but I'm going through a similar situation.

2007 Buick Rendezvous with 4T65E. Bought new. Dropped pan and filter at 50k miles as maintenance.

At 65k miles, it began to slip then bang and catch when accelerating from stop. NO other symptoms, no problems with any shift or TCC lockup.

At 75k miles, I did another pan drop and filter change.

Now the car has 95k miles.

Both of my pan drops, the filter seal looked good, so I left it alone. Really think that needs replaced? It looks like an aluminum sleeve that slip-fits to the filter neck. Feels plenty tight in there. Sciphi said something about an o-ring inside the sleeve, I don't remember seeing an o-ring on the old sleeve or the new one in the box.

It has always happened sporadically. Saturday, it happened about 5 times out of maybe 50 times I came to a complete stop. Then Sunday, Monday, Tuesday, Wednesday, and today... so far not ONCE. Temperatures, driving style, nothing has changed.

I have tried cleaning the MAF with MAF cleaner, no change at all.

I have tried one bottle of Lubeguard red, no change at all.

One thing I'm curious about is, did the 4T65E get its mechanical internals updated when the fluid spec for it changed from Dex III in 2005 to Dex VI starting 2006? We know Dex III is slightly thicker to start off, then shears down to about what Dex VI is.

Any chance the Valvoline Dex VI I use is just slightly thinner than the GM Dex VI that was put in at factory?

I've really babied this car and driven it gently. Fluid looks/smells great. Pan has never had much debris.

It does seem to only happen during the summer (Cleveland OH).

I'm tempted to try the Maxlife ATF if it's a hair thicker and the problem is fluid going past some seal that is a little weak or slightly 'off' in some way.

It just surprises me that it will happen a lot one day, and then nothing for even weeks, and then comes back.

I appreciate any thoughts!
Brian

 

[TMoto]

Sorry, didn't see this until now.

Originally Posted By: bxd20
2007 Buick Rendezvous with 4T65E. Bought new.

I believe the most common issue revolved around the pressure control solenoid (PCS) but I thought they had it resolved around 2003-2004. I can't say for certain what your issue could be but the TransGo shift kit solved mine for the max-adapt line pressure causing the hard shifts.

Quote:
Both of my pan drops, the filter seal looked good, so I left it alone. Really think that needs replaced? It looks like an aluminum sleeve that slip-fits to the filter neck. Feels plenty tight in there. Sciphi said something about an o-ring inside the sleeve, I don't remember seeing an o-ring on the old sleeve or the new one in the box.

It's not really a true o-ring as I recall, but a rubber(?) seal on the end of the aluminum sleeve. If the filter seats firmly then there may not be any harm in leaving it in place.

Quote:
One thing I'm curious about is, did the 4T65E get its mechanical internals updated when the fluid spec for it changed from Dex III in 2005 to Dex VI starting 2006?

I don't think the fluid will have much bearing on the issue but I do like MaxLife ATF.

I would take it to a shop for diagnosis. Triple Edge Performance is also a good resource.