TC lockup question

[driver456]

My TC locks up like it should,but when the car seems to warm up it unlocks And locks up when it wants and not when I want it too.It has a mind of its own.It will lock in OD and when I'm cruising along around 60-65 it unlocks and won't lock back up,No matter how much throttle I give it or let off.I tried all kinds of settings.I put a shift kit in,But I don't think that has anything to do with it,Does it?I have the right amount of fluid.Can't figure it out....................Paul

[foff667]

running the stock cam?

[Chris81]

I've got a friend's truck with an LS1 swap a higher stall converter that does this as well..

I've heard to set C5601 (misfire detection) to 1 and it fixes it, although it won't catch a misfire anymore.

Thats just what i've read, I haven't tryed it on his yet..I need to though.

[driver456]

running the stock cam?
No,I have a 598/603 114 Lsa. It worked fine when I had 3.42's and a 2600 stall put in,Over the winter I did H/C,headers & 3.73's.I'll try what Chris81 said.....Thanks..................Paul

[foff667]

i just bumped my misfire tables up slightly when i did my heads/cam otherwise it would lock & unlock randomly...worked for me.

[jfpilla]

Another method is to set all the misfire tables to 32000. You can then, by trial and error, back the numbers down to a level that works. It may not be necessary to do every table either. I just leave mine at 32000.

[driver456]

I did what Chris81 said and it seems to be working fine now.......Thanks guy's.I have to know,What does the misfire tables have to do with the TC? And how did anybody figure that out???????:nixweiss:

[ChipsByAl]

This might help you out driver456
"On automatic transmission equipped vehicles, the torque converter clutch (TCC) will disable whenever a misfire is detected. Disabling the TCC isolates the engine from the rest of the drive line, and minimizes the effect of the drive wheel inputs on the crankshaft rotation.

When the TCC is disabled as a result of a misfire detection, the TCC will re-enabled after approximately 3200 engine revolutions if no misfire is detected. The TCC remains disabled whenever the misfire is detected, with or without a DTC set. This allows the misfire diagnostic to reevaluate the system."

[jfpilla]

ChipsByAl is pretty much correct. The converter is unlocked to isolate the drivetrain from shock. But not just any misfire will unlock the converter or set codes. Every engine has some misfire. That's the reason why the number of misfires within a timeframe is required to sense it as "not normal" misfire. Raising the counts to get beyond what is the new norm is best, since some misfire can still be detected. That's hard to do though.

[ToplessTexan]

What does the misfire tables have to do with the TC?

The converter is typically much lighter than the OEM piece. This means the rotating mass is less and will accelerate more rapidly given the same applied force than in the stock configuration. The misfire detection logic (which is essentially "is the crank where I think it's supposed to be when I think it's supposed to be there?") was built with certain assumptions in mind, rotating mass being one of them.

It's important to note that the converter is not causing misfires. It is causing false alarms in the misfire detection logic. Joe is pointing out that finding the sweet spot that maintains good detection sensitivity w/o triggering a bunch of flase alarms can be quite hard. Of course, any improvement over no detection at all is a step in the right direction IMHO.

[joecar]

The misfire detection logic makes use of crank angle error data collected during a CASE relearn;
would doing a CASE relearn help in this situation...?

[Joel_SS]

i just bumped my misfire tables up slightly when i did my heads/cam otherwise it would lock & unlock randomly...worked for me.


I did the same thing and it seems to work fine.