TCC Lockup Issue

[DrX]

Looking at my Trans logs I see that the TCC is releasing at 66 kmh in 3rd rather than 50kmh as per the tune. 65 kmh is the appropriate release speed in 4th according to my tune. This explains why the TCC is constantly locking/unlocking in 3rd. Why isn't the correct table being used?

http://i114.photobucket.com/albums/n241/TDOC2004/TCCRelease3rd.jpg

Also seems that the TCC is locking during upshifts even though D2801 is set to "NO"??

http://i114.photobucket.com/albums/n241/TDOC2004/TCCLockUpshift.jpg

[DrX]

Here are the tables:

http://i114.photobucket.com/albums/n241/TDOC2004/TCCReleaseTable3rd.jpg

http://i114.photobucket.com/albums/n241/TDOC2004/TCCReleaseTable4th.jpg

[DrX]

Tried copying the 3rd gear TCC Release Normal column to the 4th gear table to see what would happen. No change. TCC still releases as soon as TP goes below 15%. Is there anything else that controls TCC release other than these tables? TCC throttle release tables are all at 100%.

Also noticed that the Gear PID never shows P, R or N. It shows 1st gear for all of these. Is this normal?

[joecar]

DrX,

PCM unlocks the TCC if misfires are detected...

But make sure the TCC release tables have a lower speed than the corresponding apply tables.

The 2nd chart images shows the TCC DC going down during the shift and never coming back up to 95+% even tho TCCMODE shows locked.

And the GEAR pid should show the actual gears as 1st, 2nd, 3rd, 4th (and not the gear selector/lever position); there maybe an alternate GEAR pid for this, check your list of PIDS.

Hmmmm.... you have something strange going on.

Joe

[DrX]

DrX,

PCM unlocks the TCC if misfires are detected...

But make sure the TCC release tables have a lower speed than the corresponding apply tables.

The 2nd chart images shows the TCC DC going down during the shift and never coming back up to 95+% even tho TCCMODE shows locked.

And the GEAR pid should show the actual gears as 1st, 2nd, 3rd, 4th (and not the gear selector/lever position); there maybe an alternate GEAR pid for this, check your list of PIDS.

Hmmmm.... you have something strange going on.

Joe

I never log any misfires. Unlock is always around 68 kmh when the throttle is below 15%.

TCC DC is always lowest in the logs when the TC is "Locked" and high when "Enabled".

Couldn't find any other "Gear" PID. 1,2,3 and 4 are indicated correctly. P, R and N are not. The gear selector position PID works properly.

Yes, Release tables are all lower than Apply tables. Going to try a copy and paste of the factory TCC tables today just to see what happens.

[Rhino79]

What gear is the selector in? D or 3? The random locking/unlocking is pretty common on cammed LS1's and those with high stall converters, but I am not quite sure if thats the case on yours. You could try increasing the values in the C5622, C5623, C5625, and C5626 tables and see if that helps.

[DrX]

What gear is the selector in? D or 3? The random locking/unlocking is pretty common on cammed LS1's and those with high stall converters, but I am not quite sure if thats the case on yours. You could try increasing the values in the C5622, C5623, C5625, and C5626 tables and see if that helps.

Selector is in D when driving. When in P, R, or N the Gear PID shows 1st. Dug up some old logs and it was the same. Does anyone see P, R, or N in their logs?

No cam here, 2600 stall. I'll check those tables. Seems to me that I already maxed them out, that's why I am not logging any misfires.

[DrX]

Misfire tables were already back to stock. But I do recall maxing them out before as an experiment. Didn't have any effect on anything. I logged the misfire PIDS last week and didn't see anything using the current/stock tables.

Tried the factory TCC Apply/Release tables today which are a little lower. The TCC still releases in 3rd at any speed when I let off the throttle. Looks like it doesn't release until TP falls to 10% though. Previously it was releasing around 15%. The release speed in the table is 40kmh for TP values of 0-25%.

It is interesting that there is a "Coast" mode for the TCC in 4th but not in 3rd. Also looks like TCC DC% is high until full lockup and responds to slip during lockup. It is also higher when holding Lock in 4th than in 3rd. Here are a few snapshots from todays log to illustrate:

http://i114.photobucket.com/albums/n241/TDOC2004/TCCDC3.jpg

http://i114.photobucket.com/albums/n241/TDOC2004/TCCDC1.jpg

http://i114.photobucket.com/albums/n241/TDOC2004/TCCDC2.jpg


Here's the log file:

[joecar]

Hmmm....

TCCDC seems to rise until TCCSLIP goes to zero... and then it went down...!!!

I was taught that TCCDC typically stays at 97+% when TCC is locked.

Are your D1008 and D1009 set to 100% all across...?

[DrX]

Are your D1008 and D1009 set to 100% all across...?

Yes.

[joecar]

I'm still scratching my head :nixweiss: , I'll have to think about this... :bash:

[SSpdDmon]

Can you post up the TCC apply tables too?? (Thinking apply tables need to be greater than the release tables for a given TP%.)


**EDIT** Looking over the logs, my first impression is that the PCM is trying to tell the TCC to lock, but it's slipping (not unlocking). What does your {D2905} TCC Pressure Apply Rate look like? If you're running a smaller, aftermarket converter...you may need to increase {D2905} and possibly {D2902}. The reason being...smaller converters have smaller TCC's. Therefore, there's less friction surface area for the clutch to grab, which may require more aggressive settings in the PCM.

[DrX]

Can you post up the TCC apply tables too?? (Thinking apply tables need to be greater than the release tables for a given TP%.)


**EDIT** Looking over the logs, my first impression is that the PCM is trying to tell the TCC to lock, but it's slipping (not unlocking). What does your {D2905} TCC Pressure Apply Rate look like? If you're running a smaller, aftermarket converter...you may need to increase {D2905} and possibly {D2902}. The reason being...smaller converters have smaller TCC's. Therefore, there's less friction surface area for the clutch to grab, which may require more aggressive settings in the PCM.

I was running all the stock TCC Apply/Release tables during that last log. Still had the release in 3rd issue whenever the throttle was released. The tables shown above are bumped up from stock and so were the corresponding release tables. I couldn't see any conflicts between those Apply and Release tables or the factory tables.

I have always left the pressure tables stock as I wasn't sure whether an increase was needed with the triple disc converter. D2902 is 827.

D2905:
http://i114.photobucket.com/albums/n241/TDOC2004/TCCPressureApplyRate.jpg

In the log it looks like the TCC is slipping at lockup in 4th only and TCC DC % increases until lockup is accomplished then drops off. The converter fully locks in 3rd but releases immediately when the throttle is released.

[DrX]

Just took a closer look at the stock tune and it looks like it was never intended for the TCC to apply in 3rd. The TCC apply speeds for 3rd are all higher than the 3-4 shift speeds.

So I was thinking that perhaps there is no "Coast" mode for 3rd written into the tune. But I was playng with the Throttle Cracker table trying to get TP as low as possible when coasting and I did log a couple of short "Coasts" in 3rd before the TCC released. Could be some unseen tables??

Also noticed that on a stock vehicle the TCC never completely locks. There is always a little slip, say 40-50 RPM whereas mine goes to 0 which might explain the harshness. Seems that I read something about this before. I'll have to re-read the TCC "Description and Operation" in the service manual.

[DrX]

In the stock tune, the TCC release in 3rd is also at or above the 4-3 downshift speed. So the TCC is never locked in 3rd. The tables are setup so that the 3-4 upshift initiates lockup and the 4-3 downshift initiates release.

[ScarabEpic22]

Keep us updated, I have a similar issue with my 4L60E trans being fine until 4th TCC lockup when it is weird and I cant figure it out.

[driver456]

When I had a problem with TC locking & unlocking some one on the forum told me to set {C5601} MISFIRE DETECTION MAX TEMP to 1 degree and the problem is gone.Normal was 266*....................Paul

[DrX]

When I had a problem with TC locking & unlocking some one on the forum told me to set {C5601} MISFIRE DETECTION MAX TEMP to 1 degree and the problem is gone.Normal was 266*....................Paul

Haven't tried disabling it that way. No misfires logged with it active though. Unlock only occurs when the TP falls below 10% under coast conditions. Doesn't matter what speed I'm at

[DrX]

This is the description and operation of the stock TC from the service manual:

"A torque converter with an electronically controlled capacity clutch (ECCC) This transmission is equipped with an ECCC. The pressure plate does not fully lock to the torque converter cover. Instead, the pressure plate maintains a small amount of slippage, about 20 RPM, in SECOND, THIRD, and FOURTH gears, depending on the vehicle application. ECCC was developed to reduce the possibility of noise, vibration, or chuggle caused by TCC apply. Typical apply speeds are 49-52 km/h (30-32 mph) in THIRD gear and 65-73 km/h (40-45 mph) in FOURTH gear. Full lockup is available at highway speeds on some applications."

My PI Vigilante TC completely locks and at a higher speed as per the tune. Could explain why it is so noticeable.

[ScarabEpic22]

Interesting, well I cant try playing with that parameter as the LL8 doesnt have it...

[joecar]

I believe there a few as-of-yet-undiscovered trans. tables.

[ScarabEpic22]

I believe there a few as-of-yet-undiscovered trans. tables.
Hope you are right, should be the same as a regular 4L60E trans, difference is that the ECM and TCM are together in the PCM in the I6.