Ok, I hear this issue all the time, its time for a sticky.

Guys/Gals with automatic cars listen up!

When you switch to a nice high stall torqe converter, the PCM can no longer use its default program to determine engine misfire. Here is the reason: The corque converter is part of the rotating mass of the engine's rotating assembly. When you reduce the wieght of the converter you are reducing the amount of Flywheel effect. The computer's stock tune is very sensitive to this rotating mass. Therefore the computer can no longer accuratly read engine misfire.

The computer has a logic routine that has certain perameters to be met before the computer locks the TC. They are (as far as I can tell):

1. Throttle position vs. MPH (normal cruise tables)
2. Engine coolant temperature > ???F (not accessable in edit)
3. > 40-50 misfires per 200 revolutions (not accessable in edit)
4. TPS = WOT

After these parameters are met, the computer waits 4-5 seconds then locks the converter.

So, for this thread the number three is the issue. Now keep in mind this is NOT code based. If you disable code PO300, this problem still exists, cause it is only looking at the current misfire count. there are only two ways (in Edit) to prevent these faulse misfires from affecting the TC lockup:

1. Set the misfire activation temperatures to 141 and deactivaion temps to 142. This is the easiest method, but its drawback is the complete disabling of the misfire detection/trouble shooting.
2. This method is more trial and error, it involves adusting the time delays of the misfire program in edit for the various ranges of detection. I personally don't use this method, so someone who does feel free to chime in here.

After disabling the misfire detection, barring any mechanical failures, the person should have little to no issues with TC lockup. I hope this helps, please feel free to direct people to this thread if you see they are haveing a TC lock up issue after installing a new torque converter.

Ryan K.
LS1 Edit Beta Tester

 

I feel it is more caused by big cams than by just changing converters. I run Yank ST3500 converters in both of my cars and another car I no longer own. I never had lockup problems with these converters with the stock cam, 02 LS6 cam and Comp 212/218 cam. As soon as I went to a Comp 216/220 and larger, the lockup problems started. I just set all the values in the idle, low, and medium misfire tables to 32767. I do not change any values in the high tables so real misfires will still be detected at high rpms. My converter locking and unlocking problems have completely gone away and lock up is rock solid now. I also do not turn off any misfire codes (p3xx).

 

The lighter the converter, the more pronounced the problem. I had this issue with just a Yank 3000. Some cars respond differently.

Thanks for the input!

Ryan K.

 

I have a stock cam and did some logging on a few WOT runs and atap recorded 253 misfires. WOW I was shocked. I also have problems with the car hunting for idle at low rpms rolls or in reverse. I've been reading but I still haven't been able to fix it yet.

 

That's awesome. I adjusted my tables to 32767 as suggested and that worked like a charm. I have a 3000 stall by Torco along with an F1 cam...voi'las. Thanks!

 

[QUOTE=2xLS1] I just set all the values in the idle, low, and medium misfire tables to 32767. I do not change any values in the high tables so real misfires will still be detected at high rpms. QUOTE]

I checked my stock misfire tables, and my high tables were already set at 32767. I changed the rest though.

 

Does anyone know where I can change the misfire tables to 32767 in hptuners?

 

That is a good question. I would like to know that also!

 

in HP tuners, under Engine Diag Misfire tab, go to the tables that you want to enter the 32767 value, select "Replaced by", enter the value in the right box, change the radio button to "All" if you want the change for the entire table. Then click on "Commit".

Personally, I don't want use the 32767 value for all the tables. Depending on how big the cam is, I would just change any cell that has value less than let's say 2000 to 2000. That way the PCM still can detect misfires, but the misfire # may not be large enough, unless there are issues w/ the motor causing a huge # of misfires, to unlock the TC.

Good luck,

 

I have a Mid west 10/12 converter, and have tried all of these fixes. Nothing seems to work! I have had this problem since I installed the converter, even before the heads and cam install. I will try anything to stop this annoying problem.

 

could be a bad converter...have you called Midwest?

 

I don't have or really know how it use any of the programs for an LS1, but I was wondering if a dyno tuner would be able uncover these sensitive problems when tuning a stalled A4?? I always read about people having trouble on the dyno with a stalled A4, mostly because the operator didn't know much about dyno runs with an A4.

 

Sure, if the tuner will actually spend time tuning the car, then all problems should be addressed.

 

Will not having this problem corrected hurt the car? The tune in my car now did not take care of this problem, and I am afraid it could hurt the tranny/stall...

 

the only thing i can see it doing is because your converter would unlock at highway speeds could overheat your tranny more then normal...log your temps and see if they get out of hand.

 

what is the pertinence(sp?) of the 32767 #? is there something special about it? Also what does it represent? like missfires per minute or hr er?

Thanks
Bill

 

Thanks.

 

Worked like a charm. Thanks for the info. Now how do I get the car to not surge at low speed with the converter locked up? I guess the 228/228 cam is a misfire maniac.

 

Under DIAGNOSTIC
MISFIRE DETECTION
There is Max temp
Min temp
To cancel misfire detection which is 141 and whaich is 142
I assume max is 142 and min is 141
Thanks

 

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