Transmission Slipping? Gmt900 W/3600mi

jgold121 · October 23, 2009

So something strange has started the other day.

I've had my BlackBear tune for about a month, and I've loved every second of it.

The other day, when the weather started to get a little cooler, than my 2-3 shift felt really sloppy. It almost felt like it was slipping. Their was a distinct "whrrrrrr" sound coming from the rear, and I couldn't tell whether it was a sound made by some drivetrain related issue, or whether it was a groan coming from the exhaust. Regardless of where the sound was coming from, I could definitely tell that there was something going on with the shift point. It felt like it was struggling to get in gear. It happened at all levels of acceleration, but was most noticeable around the 1500RPM point on a featherlight acceleration.

I got kind of nervous, so I swapped out my stock TCM, and the problem seemed to subside slightly, but I could still tell it was there.

I did a few more tests. Put the truck in neutral, rev'd up to 1500 RPM (where I was having the worst luck with it) and sloowwwllly let off the accelerator. At about 1400 RPM, the truck would all of a sudden throttle down to about 400RPM, and you could hear the exhaust go silent for a brief second...as if the truck was about to stall out.

I swapped my stock ECM back in (with the stock TCM accompanying it) and again, things got better....but they weren't like the truck ran a month ago.

Also, once I get up to speed in 4th, there's a point when the needle is hovering around 1500RPM, that if I try to accelerate, the engine RPMs will drop down as quickly as I press the accelerator to about 1100RPM. Finally, it will downshift, but not before this distinct power loss.

Does anyone have any clue as to what's going on?

I want to say that the whole engine sputter thing might amplify the issue with that shift point---where the hesitation that I'm feeling as slippage, is in reality, something to do with the engine struggling.

Any sensors that might cause this? Could it be an issue with the crank re-learn that I got? Bad gas? I've filled up a couple times since, with quality Shell fuel. I'm clueless...

It's just got me concerned---thinking that I might have screwed up the tranny having too much fun with the tune---or possibly some seal in the transmission. I've read on the board that there's been problems with the 2-3 shift point, but I thought that would've been fixed in the 2009 model year.

Any help would be greatly appreciated, guys.

-jG

gnet158 · October 23, 2009

I doubt the blackbear tune is the cause of your issue. Here's what I'd do.

1. Make sure you have enough tranny fluid.

2. Put back the Blackbear tune and disconnect the neg battery terminal for 20 minutes. Then reconnect it and let your truck's PC relearn everything.

3. If your still having the same issues then remove the blackbear tune and replace it with your stock PCM.

4. Remove the neg battery cable and run the same thing as in step 2. If you still have issues then it's your tranny and have it serviced under warranty.

Good luck and don't worry about getting it fixed under warranty. Just don't tell them.

compulynx · October 23, 2009

I doubt the blackbear tune is the cause of your issue. Here's what I'd do.

1. Make sure you have enough tranny fluid.

2. Put back the Blackbear tune and disconnect the neg battery terminal for 20 minutes. Then reconnect it and let your truck's PC relearn everything.

3. If your still having the same issues then remove the blackbear tune and replace it with your stock PCM.

4. Remove the neg battery cable and run the same thing as in step 2. If you still have issues then it's your tranny and have it serviced under warranty.

Good luck and don't worry about getting it fixed under warranty. Just don't tell them.

And hope no one there reads GM-Trucks.com, since you have your name, location, and a photo of your truck posted in the same thread where you said you had a tune and were having fun with it.....

I'm just sayin'

C

rodram · October 23, 2009

....don't worry about getting it fixed under warranty. Just don't tell them.

.. do you think this is dishonest in any way....?

.. is this how you teach your kids ...?

My guess is your transmission is pooched... or getting there already... maybe a GM defect... maybe something you did "poor 2-3 shift" usually indicates some clutches are wearing out or maybe a shift solenoid is malfunctioning....

.. best to take it to the dealer and see what they have to say

tjcbenz · October 23, 2009

....don't worry about getting it fixed under warranty. Just don't tell them.

.. do you think this is dishonest in any way....?

.. is this how you teach your kids ...?

I would not consider this dishonest. The dealer MAKES MONEY when they fix something under warranty. Sure, not as much as if it was customer pay, but they still make money off the parts and the labor. The manufacturer pays the bill. When I worked at a M-B dealer, we did everything we could to get things covered under warranty....money for us and the customer is happy. Unless it was absolutely blatant, we didn't ask any questions. The benefit of the doubt always went to the customer.

All that being said......I don't think there is anything that a simple tune would have done to toast a trans. Just look at all the people on this forum alone that have had a Blackbear Tune (myself included) with no issues.

jgold121 · October 23, 2009

Checked the tranny fluid. Not sure what this means:

Followed normal procedure of driving around until the tranny heated up to about 150F. Parked on level ground, idled, went through the whole range, idled. Checked fluid. Just a hair above the "Cold" range. I know the manual states that the tranny fluid is between 180-200F is considered hot...but the highest I've ever seen my fluid get is 160.

Y'all just think I need to add some fluid?

bbwb · October 23, 2009

I wouldn't screw with it and would just take it in and ask the dealer to check it out.

bbwb

redvett · October 23, 2009

Make sure you put in the OEM PCM and drive it a couple of miles as the counter will register how many hours its been since the PCM was changed or battery unhooked.

Read this about warrany.

Corporate Bulletin Number 08-06-04-033 is currently available in SI.

Identifying Aftermarket Engine Calibrations 2.0L, 2.2L, 2.4L, 2.8L, 2.9L, 3.0L, 3.1L, 3.2L, 3.4L,

3.5L, 3.6L, 3.8L, 3.9L, 4.2L, 4.3L, 4.4L, 4.6L, 4.8L, 5.0L, 5.3L, 5.7L, 6.0L, 6.2L, 7.0L, 7.4L, 8.1L

Gas Powered Engines Only

Models: 2006–2009 GM Passenger Cars and Light Duty Trucks

2006–2009 HUMMER H2, H3

Excluding Pontiac Vibe, G8, Chevrolet Aveo, All Saturn and Saab Models

Important: This bulletin applies to Gas Powered Engines ONLY. For Diesel Powered Engines, refer to Service Bulletin #08-06-04-006A.

If a suspicious hard part failure is observed in the engine, transmission, transfer case or driveline, perform the calibration verification described to determine if a non-GM issued engine calibration is installed. Non-GM issued engine calibrations subject driveline components to stresses different than the calibrations which these components were validated to. Repairs to transmission, transfer case and/or other driveline components where a non-GM engine calibration has been verified are not covered under the terms of the New Vehicle Warranty.

Instructions for Confirming Calibration Verification Number (CVN):

1. Go to TIS2WEB

2. Select "Calibration Information (SPS Info)"

3. Enter VIN

4. Select "Get Cal ID"

5. Select "ECM Engine Control Module"

6. Select "Next"

7. Select "Complete History"

8. Print

9. Take the printout to the vehicle along with the Tech 2®

10. Plug in the Tech 2®

11. Go to diagnostics and build the vehicle

12. Select "Powertrain"

13. Select "Engine"

14. *Select "Engine Control Module" or "PCM"

15. *Select "Module ID Information" or "I/M Information System" if module ID information selection is not available.

16. *If "I/M information System" was selected in step 15, it may be necessary to select "Vehicle Information" in order to display the calibration information.

17. Compare the calibration ID and Calibration Verification Numbers (CVN) to the Calibration Verification Numbers (CVN) on the printout.

* Steps may vary by controller.

Although the part numbers will be the same for each, it's the CVN that will determine if the calibration is GM issued. If ALL of the CVN's are EXACTLY the same, the calibration is GM issued.

If the part numbers match and ANY CVN's DO NOT match the printout, it is likely that a non-GM certified calibration has been installed.

If the CVN information is displayed as "N/A", it will be necessary to contact the TCSC to obtain the CVN information.

If a non-GM calibration is found to be in the ECM (CVN's on the Tech 2 do not match TIS printout) - In order to document the case — a CLEAR digital picture should be taken of the Tech 2® screen showing the VIN and the CVN's that do not match the TIS2WEB printout. The picture, VIN and reason the vehicle is currently in for service should be emailed to [email protected] and STEVEN.R. [email protected] for verification. Please copy your GM District Service Manager (DVM) on the e-mail. GM will verify if the CVN's are not GM issued and respond via e-mail within 72 hours.

deyomatic · October 24, 2009

I had a 2007.5 for awhile and that tranny felt really junky...sometimes it would feel like it was slipping on acceleration, but other times it did this really odd thing where when I was slowing to a stop the tranny would also slip...the first few times I thought I had been rear ended. I felt and heard a loud bang but when I checked my rear view there was nobody behind me. I never had a tune on it.

jgold121 · October 24, 2009

I had a 2007.5 for awhile and that tranny felt really junky...sometimes it would feel like it was slipping on acceleration, but other times it did this really odd thing where when I was slowing to a stop the tranny would also slip...the first few times I thought I had been rear ended. I felt and heard a loud bang but when I checked my rear view there was nobody behind me. I never had a tune on it.

Feeling the same thing.

And then whenever I decelerate, you can literally feel it downshifting, and with the windows down, hear the engine groaning. So strange...

gnet158 · October 24, 2009

Are you serious, come on, really? Unless when the op said he "enjoyed the tune a few times" ment he went to the drag strip then I doubt it's the tune. And GM's no saint either, how many times have they gotten out of warranty work when it should have been covered, piston slap is just one that comes to mind.

....don't worry about getting it fixed under warranty. Just don't tell them.

.. do you think this is dishonest in any way....?

.. is this how you teach your kids ...?

My guess is your transmission is pooched... or getting there already... maybe a GM defect... maybe something you did "poor 2-3 shift" usually indicates some clutches are wearing out or maybe a shift solenoid is malfunctioning....

.. best to take it to the dealer and see what they have to say

deyomatic · October 24, 2009

There was a time, not really THAT long ago, when GM designed transmissions to be able to withstand the power of the engines they installed in front of them. They didn't need arguably dishonest things like "Torque Management" to make sure their components didn't break. In the 60s they made 425+ HP V8s and had several transmission options that would survive. Now they can't make one that can reliably take 325HP so they use computers to minimize their repair costs. And we just gave them billions...

I wouldn't feel guilty at all. If they made the truck with the power you wanted in the first place, you would have bought that one.

WilliamBos · October 24, 2009

If you play with fire, you are gonna get burned. If GM covers it, be thankful, but if they deny it and flag the truck, can you really blame them?

jgold121 · October 24, 2009

If you play with fire, you are gonna get burned. If GM covers it, be thankful, but if they deny it and flag the truck, can you really blame them?

Do you honestly think that with 1000 miles driven with a tune (and when I say "had fun"---I meant race a Ford or two at a stoplight) that you should have clutch trouble on a brand new truck? I wasn't running moonshine or anything...

I don't care if this truck had a stick shift and I burned it out 24/7---you should be able to get more than 500-1000 miles on it.

WilliamBos · October 24, 2009

Do you honestly think that with 1000 miles driven with a tune (and when I say "had fun"---I meant race a Ford or two at a stoplight) that you should have clutch trouble on a brand new truck? I wasn't running moonshine or anything...

I don't care if this truck had a stick shift and I burned it out 24/7---you should be able to get more than 500-1000 miles on it.

Return it to stock, drive it to the dealer, tell them it is broken, and you will find out if GM will cover it, and what is wrong.

Play stupid and like others have said, hope that GM does not log in here and read forums, or do a google search on your name to see what comes up.

Good luck, keep us posted.

My 2 kopeks, warranties are nice things to have, so why jeopardize it. Safest bet is leave it stock until warranty runs out, or do so at your own risk. It is your truck, do what you wish.

JMHO.