ATXKJ wrote:
If the Torque Converter locks at 1200-1300 rpm - I think you'll still pickup performance even if it revs higher to shift - you'll have the TC locked - before the lockup is engaged by the TCM. - not certain but I think it'll be better.
Yes. It should be much better.
I as I now understand it, the loss in power in F37 results from two things:
1. The TCM telling the ECM to retard engine power, resulting in less overall power.
2. The higher stall torque converter not engaging until after the engine is past its peak torque (1800 engine rpm, 2200?? stall speed). Resulting in less pulling power off the line and lower gas mileage in stop and go driving.
What percent of the overall power loss reported by DC is due to 1 versus 2 we don't know. We don't even know the total power loss-- hence the interest in the dyno numbers.
The new shift points have little to nothing to do with the power loss and are a seperate issue. Several like the new shift points as they seem to get better highway miles.
For the first problem, the TCU is telling the engine to retard power to save the cheap torque converter/tranny-- we can't work around it without a flash. We don't know what is going on in there because it is closed source software-- and DC is not going to tell us what it does or show us the code. It is alot like installing service pack 5000 from Microsoft. You know you need it to fix bugs, but you don't know how it fixes them, if it even fixes them, and what it might break. To make it worse, we can't reinstall and start over-- like you can with Windows.
The second problem can be fixed. The higher stall torque converter is why some people are seeing worse mileage in town (wheras those who see highway miles are probably getting better mileage after F37 because of the new shifting pattern). The worse stop and go gas mileage occurs because the engine is reving past its peak power point before the transmission makes a serious effort to move the vehicle off the line-- wasting fuel by running the engine outside its power band, The higher stall was used to let the engine quickly get the RPM's up past the the peak torque point. As the torque drops fast, the converter spends much less time with higher torque being applied. Many fear that simply putting in a better torque converter will not be enough on its own to solve the problem. The fear is that the heat disappation ability of the tranny and its pump is too low for the higher torque ratings-- and that the heat generated by those higher ratings will result in fluid heating that will kill the torque converter. Chipping your engine will make this worse-- as it changes the torque curve dramatically extending it into the higher RPMs. DC's solution is the cheap one-- but it should work for people who don't mind the power loss and the worse in- town gas mileage.
If you tow or offroad, or want good gas mileage in town, you are not one of the ones this will work for. If you spend lots of time moving the vehicle from a standstill-- you will defeat the purpose of the higher stall torque converter installed with F37. Instead of quickly getting the engine to a point where it produces less torque (and heat)-- you will be constantly producting maximum torque at low engine RPM for prolonged periods. Wheras this was occuring before F37, before it had a lower stall. With a lower stall, the converter would be using as much of that power to push against the wheels as possible. With the new high stall converter, that power goes somewhere else--- straight into resistance-- creating massive HEAT!! If you do this for along time-- say when climbing obstacles off-road at slow speeds-- you are generating significatly MORE HEAT than if the stall was lower. The new torque converter is likely to cause more damage than good in these situations. So if you wheel at slow speeds, the F37 torque converter spells an even earlier torque converter and transmission death. If you chip it-- you increase the torque across the band, and can probably expect an early death as well.
My solution:
I am going to go in and get the F37 done-- with the new pump (hoping that the pump is more efficient) and the intercooler. Then I am turning around and getting the ATS 5-star torque converter Yes, this may be like hitting a fly with a hammer, but the 5 star spends most of its time in lock up (direct connect where the fluid is not used to transfer power or generate heat)-- it is in partial lockup almost all of the time. Then I will flash the ECU with stage-II, mainly for fuel efficiency reasons and also to have the power when I want it. I think-- along with a provent, a total EGR disconnect, and some upcoming solution to the fuel leak problems, I will have the remaining issues fixed. I am still debating the Transgo shift kit. I am going to call around and see if this is more of a help than a hidrance. I know it makes it shift firmer-- with less slipping and heat production, but I don't know if it is compatible with F37. I don't think the dealer will install it, so it may wait until 30,000 miles down the road when I next change the filters and fluid. If the tranny pukes before-- I will get a custom built racing tranny and wire up another in-line tranny cooler.
If the TCU is eventually cracked by inmotion, or someone else-- then I will flash it as well. I would really like it if the flash is smart enough to give me on-the-fly adjustable shift points (different modes-- and no more adaptive learning crap), the ability to put it in 4th instead of just 5th to 3rd and the ability to tell the torque converter to stay locked when engine breaking-- as the ATS can handle staying locked (5 huge clutches as opposed to one wimpy one) and staying locked will keep the tranny much cooler while resulting in better engine breaking performance (this thing does seem to engine break-- I suppose that is thanks to the flow control valve, but not sure.).
This is alot of effort and cash, however, and it has sucked up everything I was going to use to put a 4inch lift on it and buy Rock Lizard sliders/bumpers. But what good is a lift if it does not go? Trail-Rated is what the vehicle should have been designed to do, it is what they sold it as capable of being able to do and I am having to spend lots of cash fixing stupid crap that I should not have to mess with. I not happy with DC, but I am determined to have what I want when I am done with it.
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