Thread: KR.... Educate me please

Originally Posted by BrandonHall10

Why is it...

From a 40 roll, when I stab the throttle, it drops a gear and I can see the KR spike to 10+ degrees. I let off after a second, but not more than two.
BUT...
From a stop, or even if I'm already moving, if I roll the throttle to 100%, I can run all the way up to the shift with less than one full degree.

Current mods:
E85, 1;9RR's, Headers, 3.1" pulley. The only thing engine/fuel related I changed in the tune was scaling the injectors for E85.

Can someone explain why aggressive throttle entry would cause so much KR, but slow(er) entry would cause almost none? Just looking for knowledge.

Thanks.

I finally have an answer, because I just figured it out myself. At higher power levels the torque converter if stock will act strange sometimes. On a stock trans tune, the TCC does not unlock the converter until almost 50% throttle. That's an enormous amount of load placed on the converter that's suddenly broken free. This effect is amplified if you have a larger throttle body (I have a Northstar), as 50% throttle position on a N* is way more than the same TPS on an L67 TB... The result being the TCC stays locked far longer than it should.

For some reason when it releases under load it generates a noise that reads as a massive amount of KR.

I first suspected my 42# injectors were too small for the job so I put 60's on, only to have the same problem.

So, we lowered the TCC unlock threshold with the tuner to a more reasonable 25%... And voila, the KR was 1-2 degrees.

In other words, I just need a beefier torque converter.

Word player, I was just gong to say it's the converter trying to unlock.

Originally Posted by hensleya1

I finally have an answer, because I just figured it out myself. At higher power levels the torque converter if stock will act strange sometimes. On a stock trans tune, the TCC does not unlock the converter until almost 50% throttle. That's an enormous amount of load placed on the converter that's suddenly broken free. This effect is amplified if you have a larger throttle body (I have a Northstar), as 50% throttle position on a N* is way more than the same TPS on an L67 TB... The result being the TCC stays locked far longer than it should.

For some reason when it releases under load it generates a noise that reads as a massive amount of KR.

I first suspected my 42# injectors were too small for the job so I put 60's on, only to have the same problem.

So, we lowered the TCC unlock threshold with the tuner to a more reasonable 25%... And voila, the KR was 1-2 degrees.

In other words, I just need a beefier torque converter.

Same thing I've just noticed on mine. I get 3-4 degrees KR when it downshifts, and was wondering what tcc table exactly to try to adjust. I'll try what you did, thanks.

Originally Posted by fst

c the other thing someone mentioned is the converter not unlocking soon enough and the extra load is on there when in boost. i can bet yours is unlocking above 35% throttle. see if you can lower it to either 30% or like mine, around the 25% mark (i start getting into boost at 30% throttle)

i'll leave this right here :-p

Originally Posted by bandook

Same thing I've just noticed on mine. I get 3-4 degrees KR when it downshifts, and was wondering what tcc table exactly to try to adjust. I'll try what you did, thanks.

on the tuner look for TCC apply and release parameters for 2nd, 3rd, and 4th gears. You'll see at which speed versus TPS the tcc will apply. Change anything above 25% throttle to something absurd like 255 mph so it never happens. You'll see those same numbers for higher throttle settings already

Originally Posted by fst

i'll leave this right here :-p

OK, wifey. You were right and I was wrong

AFAIK tcc doesnt apply in 2nd gear from factory unless you make it to.

Originally Posted by hensleya1

on the tuner look for TCC apply and release parameters for 2nd, 3rd, and 4th gears. You'll see at which speed versus TPS the tcc will apply. Change anything above 25% throttle to something absurd like 255 mph so it never happens. You'll see those same numbers for higher throttle settings already



OK, wifey. You were right and I was wrong

OK thanks. Were you also getting kr while in 4th under load? If I'm going 40-45mph up an incline I always get kr.

Originally Posted by hensleya1

on the tuner look for TCC apply and release parameters for 2nd, 3rd, and 4th gears. You'll see at which speed versus TPS the tcc will apply. Change anything above 25% throttle to something absurd like 255 mph so it never happens. You'll see those same numbers for higher throttle settings already

So like, from this:


to this: (?)

Originally Posted by bandook

OK thanks. Were you also getting kr while in 4th under load? If I'm going 40-45mph up an incline I always get kr.

yes my fix was lowering the timing in the GFS table where you're getting KR. in my DHP table i lowered it by 2 degrees, somewhere from 12-13* down to like 9-11* in the 1800-2200 RPM and in the 3/4 row cylinder pressure.

edit-the other bandaid is tap the brake with the left foot (or let off the gas pedal so the tcc unlocks) and apply enough gas to just be near zero vacuum right before going into boost (~27-29% throttle) to go up on the incline. this is with the tc unlock at 25% btw

Originally Posted by BrandonHall10

So like, from this:


to this: (?)

We have a winner

What TB do you have though?

with the revised table (2nd one) the tcc will unlock when you go over 18% instead of the 25%.

Originally Posted by hensleya1

What TB do you have though?

Stock

Originally Posted by fst

with the revised table (2nd one) the tcc will unlock when you go over 18% instead of the 25%.

Woops... So, this: (?)



That would put the unlock OVER 25%

Originally Posted by BrandonHall10

Stock



Woops... So, this: (?)



That would put the unlock OVER 25%

with a stock TB I would recommend over 25%. Otherwise it'll break loose when climbing a hill or just randomly. I have a N* and mine is set to anything above 25

only if he is flooring it going up (pending mods ) but if only just to unlock the tc and maintain or increase his speed gradually with flow of traffic, at 25% is fine imo