Open loop in 87 performance tune??

Chris74 · #1 Tue, February 24th, 2009, 03:18 PM

I know Bill is away and he'll likely confirm this when he gets back.......but does anybody know if our trucks will go into open loop under say light to moderate acceleration. I mean while on one of Bill's custom 87 performance tunes (or even 91 or tow tune).
If so, at about what rpm would they do that? I assume it will immediately revert back to closed loop once you level out to say a 65mph cruise?
I know it's open immediately at WOT but I'm wondering with the custom tune if it opens up at say half throttle.
I'm getting my truck dynoed on Friday and plan to do atleast one partial throttle pull to check the a/f at a light load cruise as well.

Dfishrmn · #2 Tue, February 24th, 2009, 04:32 PM

Quote:

Originally Posted by Chris74

I know Bill is away and he'll likely confirm this when he gets back.......but does anybody know if our trucks will go into open loop under say light to moderate acceleration. I mean while on one of Bill's custom 87 performance tunes (or even 91 or tow tune).
If so, at about what rpm would they do that? I assume it will immediately revert back to closed loop once you level out to say a 65mph cruise?
I know it's open immediately at WOT but I'm wondering with the custom tune if it opens up at say half throttle.
I'm getting my truck dynoed on Friday and plan to do atleast one partial throttle pull to check the a/f at a light load cruise as well.

There was some discussion on this subject in the thread "Torque Converter" in this forum. Bill indicated his tunes go into WOT at approx. 90-94% accelerator pedal position, at that point it is in open loop. Hope that helps.

Chris74 · #3 Tue, February 24th, 2009, 08:00 PM

right.....got it. thanks!

***Jackpine*** · #4 Tue, February 24th, 2009, 08:11 PM

My limited understanding of all this is you are in closed loop as long as the engine is fully warmed up and you don't get into the WOT throttle position.

I've noticed, now that I've got a Gryphon updated to show "gears", that the torque converter WILL NOT lock until things are all warmed up.

- Jack

twintips_17 · #5 Tue, February 24th, 2009, 08:33 PM

Quote:

Originally Posted by JackandJanet

My limited understanding of all this is you are in closed loop as long as the engine is fully warmed up and you don't get into the WOT throttle position.

I've noticed, now that I've got a Gryphon updated to show "gears", that the torque converter WILL NOT lock until things are all warmed up.

- Jack

I read somewhere that the torque converter won’t lock until the transmission reaches over 100 degrees.

Driving in Montana I can tell that it defiantly takes a bit before it will lock due to the cold weather.