Fluttering Butterfly or TCC?

Dad-O-Matic

Original poster
Member
Dec 5, 2011
228
Recently I've noticed that my tach fluctuates 200-300 RPMs around the 1500 RPM mark under the following conditions:

Speed approximately 45 mph
Throttle approximately 20%
Ambient temperature over 100*

My suspicion it the either the TB butterfly if fluctuating or the TCC is locking/unlocking. I've had a PCMforless tune (basic, level 2 shift and removed TM) since April and didn't notice anything until this summer when it started getting hot. I also cleaned the TB front and back when I re-installed the PCM.

Could the parameters for the PCM have been set too fine, i.e. a small variance in RPM or throttle position causes the TB or TCC to jump back and forth from one setting to another? Or should I be looking at something else?

I have Torque, is there a readout I should look at to help narrow down the problem?
 

SAR85

Member
Jan 31, 2012
74
Torque has a throttle position PID, but I believe it is commanded position, not the actual position of the throttle plate. Still, it may be helpful in diagnosis.
 

Bartonmd

Member
Nov 20, 2011
545
The TCC is locking/unlocking. Common with the PWM TCC versions of this transmission (anything after '96, I think)... The channel in the valve body that the valve floats back and forth in (which was designed for it to be at one end or the other) on PWM gets worn out, and allows more fluid around the outsides of the valve than designed. It's not expecting this, so it ramps up the pulse width, which gets into the less worn part of the channel, and locks up the TCC. The PCM sees this, and backs it off a little, which gets back into the worn part, and the TCC slips more than the PCM wants, so it upps the pulse width again, and so on, and so forth...

My dad's '00 Silverado did this at around 80k miles, and JamesDowning's (along with a couple others) did it pretty recently. There's a thread on ORTB about it (OffRoad TB - View topic - Solved - Torque Converter Clutch Flutter) and there are a number of kits that cure it. One of them re-sleeves the valve body and goes back to the PWM, and the other (like JD put in, as part of the Transgo kit) eliminates the PWM ability, and just locks 100% when the TCC is engaged. The result of the latter is slightly better mileage and cooler transmission temps.

ETA: going to the 100% locked/unlocked (non-PWM) valve does NOT trip a code or anything! The computer doesn't seem to care.

Mike
 

Dad-O-Matic

Original poster
Member
Dec 5, 2011
228
SAR85 said:
Torque has a throttle position PID, but I believe it is commanded position, not the actual position of the throttle plate. Still, it may be helpful in diagnosis.

Thanks, I'll add it to my readout

Bartonmd said:
There's a thread on ORTB about it (OffRoad TB - View topic - Solved - Torque Converter Clutch Flutter) and there are a number of kits that cure it. One of them re-sleeves the valve body and goes back to the PWM, and the other (like JD put in, as part of the Transgo kit) eliminates the PWM ability, and just locks 100% when the TCC is engaged. The result of the latter is slightly better mileage and cooler transmission temps.

Thanks, I looked at your link, the process looks both simple and intimidating. I'm pretty sure I could do it if I had the time, or another car to drive while the Envoy is up on ramps. :undecided: Just another item to add to the "to do" list.:hopeless:
 

Bartonmd

Member
Nov 20, 2011
545
Dad-O-Matic said:
Thanks, I'll add it to my readout



Thanks, I looked at your link, the process looks both simple and intimidating. I'm pretty sure I could do it if I had the time, or another car to drive while the Envoy is up on ramps. :undecided: Just another item to add to the "to do" list.:hopeless:

I wouldn't just let it do it forever... Dad's truck didn't do it with me driving, so I suspect if you drive it harder, so it doesn't go into lockup so early, it may be OK until you can get it fixed.

Dad was traveling and didn't want to mess with it, so he just paid a local independant transmission shop to do it. I think they charged like $300 or something to do it.

Mike
 

Sparky

Member
Dec 4, 2011
12,927
Let it go long enough and it'll start doing other stupid things like not even locking at all when warm, possibly throwing P1870 code, and maybe even start slamming your 1-2 shift randomly (crazy side effect I know but it does happen). Can also wear your torque converter lockup plates faster. That said, you probably have time as it just started to do it to you and as I mentioned it took me over a year to figure out what was going on with mine in my old 98 Camaro. Actually what's funny about it is that transmission has 165k miles on it and is now in my current 99 Camaro, still works perfectly.

I used the Transgo SK-4L60E kit in both my vehicles. It fixed my Camaro's lockup problems that I fought for over a year and I put it in the Trailblazer as a precaution/preventative maintenance. I went with the seller ctpowertrain on ebay and got their "P1870 code buster" kit. It comes with the Transgo kit, new valve body separator plate and seals, Sonnax pinless accumulators, and a corvette servo. Worth it as everything you need except fluid, filter, and trans pan gasket are included.

4L60E 4L65E 1996-2006 1870 P1870 CODE BUSTER COMBO KIT Corvette Servo, Kit, Book | eBay

WELL worth it.
 

Sparky

Member
Dec 4, 2011
12,927
There is a different separator plate for 07-08 and another one for 09 but I'm not sure what the differences are and why they don't have pre-made kits for them. CTpowertrain does carry the 46-PLT-07 however. Maybe send them a message and ask them to put together a kit for you with the 07 plate? They would probably do that since they carry all the stuff.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I know I should toss a kit in mine sometime. Maybe this winter.
 

Bartonmd

Member
Nov 20, 2011
545
Since mine hasn't started doing it yet, I've inquired with PCMforless about whether or not they can make the TCC PWM 100% on or off. I'll post when I know.

Mike
 

Dad-O-Matic

Original poster
Member
Dec 5, 2011
228
Sparky said:
Let it go long enough and it'll start doing other stupid things like ... slamming your 1-2 shift randomly (crazy side effect I know but it does happen).

Yep, already started that, I thought it was the PCMforless tune (#2 shift). Looks like I'll be installing this sooner than I thought. :thankyou: for the parts link.
 

Bartonmd

Member
Nov 20, 2011
545
Bartonmd said:
Since mine hasn't started doing it yet, I've inquired with PCMforless about whether or not they can make the TCC PWM 100% on or off. I'll post when I know.

Mike

Alvin didn't act like he knew what I was talking about, but I found the settings in the HP Tuners software. There's a max TCC % and a minimum TCC %. I kept the max in the 97-99% range, and changed the minimum from 11-15% to 90% across the board. TCC still applies reasonably un-abruptly, and slip stays between 0.2% and 0% (instead of the factory 2-5%). This will keep it out of the worn part of the valve body, as well, and get rid of the surging.

I sent Alvin an email this morning, telling him where the settings were, and the effects, so I would think at some point, you'd be able to order this as part of your tune?

Mike
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Mike...let me know what you find out because I could add this to my re-flash....
 

McGMT

Member
Jun 17, 2012
621
Bartonmd said:
Wonder why it ends in 2006?

Mike

I believe in 07 they switched to the 4L70-E which is supposed to have upgraded components...

BTW, I have the same problem when climbing hills at constant speed and throttle... Fluid bypassing the garbage internals... Gonna throw that kit in mine...
 

Bartonmd

Member
Nov 20, 2011
545
McGMT said:
I believe in 07 they switched to the 4L70-E which is supposed to have upgraded components...

BTW, I have the same problem when climbing hills at constant speed and throttle... Fluid bypassing the garbage internals... Gonna throw that kit in mine...

No, only the SS got the 65 or 70e. The '07 still has the 60e.

Mike
 

Dad-O-Matic

Original poster
Member
Dec 5, 2011
228
Sparky said:
I used the Transgo SK-4L60E kit in both my vehicles. It fixed my Camaro's lockup problems that I fought for over a year and I put it in the Trailblazer as a precaution/preventative maintenance. I went with the seller ctpowertrain on ebay and got their "P1870 code buster" kit. It comes with the Transgo kit, new valve body separator plate and seals, Sonnax pinless accumulators, and a corvette servo. Worth it as everything you need except fluid, filter, and trans pan gasket are included.

4L60E 4L65E 1996-2006 1870 P1870 CODE BUSTER COMBO KIT Corvette Servo, Kit, Book | eBay

WELL worth it.

Here's an alternative, a rebuilt valve body with the updated parts for those of us wary of rebuilding it yourself.

4L60E 4L65E 2003-UP M30 M32 Valve Body Remanfactured Sonnax Updated Lifetime wty | eBay

I can install it myself and no worries of messing up the valve body internals. It's only $90 more than the kit and when you're done you'll have a spare valve body to rebuild/play with. :thumbsup:

Edit: It also includes the filter and pan gasket which isn't included with the "code buster" kit.
 

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