engine surging problem
10-05-2011 | 06:39 PM
#21
New Member
Joined: 01-14-2009
Posts: 10
From: NW Washington
I have been following this thread because I have a concern too.
I have a 08 LS auto. 46000 miles. No MIL or codes. I have a Gibson cat back exhaust system installed, I can hear the engine. At 40MPH and above at light throttle application, the engine RPM's would surge up and down about 400RPM's. It is the TCC (Torque Converter Clutch) disengaging, RPM's go up, and engaging, RPM'S go back down.
I took the tec from the Chevy dealer for a ride and he hooked up his scan tool and watched. The scan showed at 5% throttle the TCM (Trans Control Module) was signaling the torque converter clutch solenoid valve to release the converter clutch. That's what caused the RPM'S to rise because there was a 5% throttle applied. A second or so later, the TCM signaled the same soleniod to engauge the clutch, the RPM'S droped down. Over and over again. The clutch should not disengage with any throttle untill the speed drops below 39-40 MPH. Lot's of ware and tear on the clutch.
So we determined there was no hardware problem, every thing works, it's a software problem.
Tec checks for a software up-grade from GM.......None.
Since the problem only started maby 9000 miles ago, and got worse with time,The tec "reset trans shift adapts" with his scan tool...........Bingo, problem solved!
The TCM computer has a adaptive shift logic software that learns how the car is dirven and adapts to it.
I had to pay $101 for this service. I said power train warranty should cover it. He says no parts were replaced so no warranty. I asked what if this happenes again in 10,000 miles, witch it probaly will, faulty adaptive software. Service guys looks down at the floor and says, you haft to pay to reset again!........Wow GM, That's pretty bad.............
I am happy that it is fixed, but when it needs to be adressed again, I'm going to make some noise
Hope this helps others..........Buck
I have a 08 LS auto. 46000 miles. No MIL or codes. I have a Gibson cat back exhaust system installed, I can hear the engine. At 40MPH and above at light throttle application, the engine RPM's would surge up and down about 400RPM's. It is the TCC (Torque Converter Clutch) disengaging, RPM's go up, and engaging, RPM'S go back down.
I took the tec from the Chevy dealer for a ride and he hooked up his scan tool and watched. The scan showed at 5% throttle the TCM (Trans Control Module) was signaling the torque converter clutch solenoid valve to release the converter clutch. That's what caused the RPM'S to rise because there was a 5% throttle applied. A second or so later, the TCM signaled the same soleniod to engauge the clutch, the RPM'S droped down. Over and over again. The clutch should not disengage with any throttle untill the speed drops below 39-40 MPH. Lot's of ware and tear on the clutch.
So we determined there was no hardware problem, every thing works, it's a software problem.
Tec checks for a software up-grade from GM.......None.
Since the problem only started maby 9000 miles ago, and got worse with time,The tec "reset trans shift adapts" with his scan tool...........Bingo, problem solved!
The TCM computer has a adaptive shift logic software that learns how the car is dirven and adapts to it.
I had to pay $101 for this service. I said power train warranty should cover it. He says no parts were replaced so no warranty. I asked what if this happenes again in 10,000 miles, witch it probaly will, faulty adaptive software. Service guys looks down at the floor and says, you haft to pay to reset again!........Wow GM, That's pretty bad.............
I am happy that it is fixed, but when it needs to be adressed again, I'm going to make some noise
Hope this helps others..........Buck
10-05-2011 | 11:29 PM
#23
Senior Member
Joined: 01-04-2008
Posts: 2,366
From: Long Beach, Ca
Can that fuse and location be verified please for a lazy F*k? Billy if this does what Im thinking, it resets the module and relearns? Man I cant believe this could be fix and it totally makes sense. I asked the squealership if they'd reflash my car - reply was it doesnt work that way and basically with no codes the car has to break before something can be done. Im so going to try this. @Buckster, dude Im so glad you posted your fix. Thanks.
10-05-2011 | 11:35 PM
#24
Platinum Member
Joined: 01-09-2007
Posts: 15,983
From: SE USA
Don-
Under the hood, fuse #41 is the ECM......... # 43 is ECM (trans)........... #42 is empty in my '08...
IDK if reflashing is same as resetting.. However relearning after a reset can take 80 - 100 miles according to Joe..
Under the hood, fuse #41 is the ECM......... # 43 is ECM (trans)........... #42 is empty in my '08...
IDK if reflashing is same as resetting.. However relearning after a reset can take 80 - 100 miles according to Joe..
10-06-2011 | 12:03 AM
#25
Senior Member
Joined: 01-04-2008
Posts: 2,366
From: Long Beach, Ca
My thoughts are if Bucksters tech reset the adaptive learning chingas with the scan tool - as you mentioned, kill power to the module and let it sit for 10 minutes or so. Power it back up and drive it as I normally do. If that doesnt work, Im printing this thread off and applying it to the service writers forehead. Reset my Adaptive Learning Chingas or you'll wish you had. 52 miles round trip to work daily, I should know in a few days after I find that fuse.
-Struts. Thanks brother.
-Struts. Thanks brother.
10-06-2011 | 12:06 AM
#26
Platinum Member
Joined: 01-09-2007
Posts: 15,983
From: SE USA
Joe's input:
WOW, just WOW!! There is SO much myth, lore, fallacy and false information in this thread I don't just know where to begin! 
Let's get started.....
"learn down": The only place I've experienced that is reading this forum! Seriously! DOES NOT EXIST on these cars, period!
Fact: There are ONLY two parameters in the OEM calibration that have a "learn" factor.
1. LTFT (Long Term Fuel Trim): This is a long term average of trimming the AFR to keep on stoic. It is learned over time based on O2 sensor feedback and takes about 80 - 100 miles to settle in. If you "reset the ECM", it will revert to zero and begin the learn process. If you don't reset, it will still "relearn" in about the same time frame and end up with the same result. So... NO difference! The biggest effect on this is changing the intake, which often will effect airflow across the MAF sensor. If the "correction" is within about 18% of target, all is fine, but definitely not ideal. Outside of that, a lean code (DTC P0171) or rich (P0172) will be thrown.
2. KLF (Knock Learn Factor: There are two ignition timing tables in the calibration, high and low. The high is the "target" timing and will work well with the recommended fuel. Say you load the tank with 87 octane... The knock sensor will sense knock and start to factor down towards the low table to eliminate knock and this is proportional. Now, next tank you go back to 93... Sensing the lack of knock, it will begin to factor up.
The above are the ONLY "learn" parameters. Resetting the ECM will do absolutely NOTHING to effect this.
Now for the transmission: All HHRs use the 4T45E trans with a T42 controller. All of the characteristics are hard coded, based upon throttle position and RPMs. There is NO "learn" based upon how you drive.
Hope this informs people and dispels some of the myths I've seen posted here.
Good luck, folks!
Let's get started.....
"learn down": The only place I've experienced that is reading this forum! Seriously! DOES NOT EXIST on these cars, period!
Fact: There are ONLY two parameters in the OEM calibration that have a "learn" factor.
1. LTFT (Long Term Fuel Trim): This is a long term average of trimming the AFR to keep on stoic. It is learned over time based on O2 sensor feedback and takes about 80 - 100 miles to settle in. If you "reset the ECM", it will revert to zero and begin the learn process. If you don't reset, it will still "relearn" in about the same time frame and end up with the same result. So... NO difference! The biggest effect on this is changing the intake, which often will effect airflow across the MAF sensor. If the "correction" is within about 18% of target, all is fine, but definitely not ideal. Outside of that, a lean code (DTC P0171) or rich (P0172) will be thrown.
2. KLF (Knock Learn Factor: There are two ignition timing tables in the calibration, high and low. The high is the "target" timing and will work well with the recommended fuel. Say you load the tank with 87 octane... The knock sensor will sense knock and start to factor down towards the low table to eliminate knock and this is proportional. Now, next tank you go back to 93... Sensing the lack of knock, it will begin to factor up.
The above are the ONLY "learn" parameters. Resetting the ECM will do absolutely NOTHING to effect this.
Now for the transmission: All HHRs use the 4T45E trans with a T42 controller. All of the characteristics are hard coded, based upon throttle position and RPMs. There is NO "learn" based upon how you drive.
Hope this informs people and dispels some of the myths I've seen posted here.
Good luck, folks!
10-06-2011 | 11:51 AM
#30
New Member
Joined: 01-14-2009
Posts: 10
From: NW Washington
The instructions for resetting the transmission adaptive functions are in the model year 2008 factory service manual, page 17-261.
The adaptive functions compensates for normal wear on the clutch fiber plates, the seals, and the springs.
Hope this helps..........
The adaptive functions compensates for normal wear on the clutch fiber plates, the seals, and the springs.
Hope this helps..........