Grumpy.....DFCO
09-19-2003, 09:55 AM
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Grumpy.....DFCO
I read in another thread (which I cant find now) that you said causing TCC to remain locked when coasting added a mpg or so. Why is this? The only thing I can see is keeping it locked will lower the MAP while coasting and cause you to spend more time in DFCO. Is that it? If that is the case, then in the $8d there is a location which unlocks when TPS is greater than the entry (0312). So I should change it to 0. But then I noticed another flag which unlocks the TCC when in DFCO (0018). Gotta fix that one also? (assuming I do want DFCO which I do for now) Am I on track here?
Thanx
Thanx
09-19-2003, 10:05 AM
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Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Re: Grumpy.....DFCO
Originally posted by Stevie
I read in another thread (which I cant find now) that you said causing TCC to remain locked when coasting added a mpg or so. Why is this? The only thing I can see is keeping it locked will lower the MAP while coasting and cause you to spend more time in DFCO. Is that it? If that is the case, then in the $8d there is a location which unlocks when TPS is greater than the entry (0312). So I should change it to 0. But then I noticed another flag which unlocks the TCC when in DFCO (0018). Gotta fix that one also? (assuming I do want DFCO which I do for now) Am I on track here?
I read in another thread (which I cant find now) that you said causing TCC to remain locked when coasting added a mpg or so. Why is this? The only thing I can see is keeping it locked will lower the MAP while coasting and cause you to spend more time in DFCO. Is that it? If that is the case, then in the $8d there is a location which unlocks when TPS is greater than the entry (0312). So I should change it to 0. But then I noticed another flag which unlocks the TCC when in DFCO (0018). Gotta fix that one also? (assuming I do want DFCO which I do for now) Am I on track here?
I remember that being mentioned, but I've always been of the philosphy of limiting the load on the TCC as much as possible. So I just lock it under very light loads, and unlock it during overrun.
Reason is, the TCC linings were too soft, and I lost a couple trannies from TCC materail shreadding and plugging up things.
While that's maybe changed some, with the 700s, I still treat em that way.
09-20-2003, 03:44 PM
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Car: 91 Red Sled
Axle/Gears: 10bolt Richmond 3.73 Torsen
I was the one that posted this, and I've got proof. Consistantly getting over 22mpg on the highway now and before it was 20, best to date was 24 but that was a bad fuel pump, not exactly a way to go about getting better milage. And my worst was 16, that was running with a vacAFPR and near stock eprom.
I personally think that the chatter of on/off of the tcc is more harm that leaving it locked in coasting decell. The clutch isn't moving when it's kept locked but it does see abuse when you leave it locked under WOT and hard braking, hence the unlock for PE and brake switch bypass. I also raised my manditory lockup speed to 80, this makes certain that when I go WOT that the TCC is unlocked or in the process of unlocking (no load).
I understand the design of the tcc enough to feel confident of this operation. I also think Grumpy's idea is correct, just more on the cautious side. Whatever you do, if you have a powerful motor (over 300 ft-lbs across the powerband), then be sure you don't leave the stock tables as they were, or you'll go through transmissions like oil changes. The unlock, lock is all setup for stock cars.
I personally think that the chatter of on/off of the tcc is more harm that leaving it locked in coasting decell. The clutch isn't moving when it's kept locked but it does see abuse when you leave it locked under WOT and hard braking, hence the unlock for PE and brake switch bypass. I also raised my manditory lockup speed to 80, this makes certain that when I go WOT that the TCC is unlocked or in the process of unlocking (no load).
I understand the design of the tcc enough to feel confident of this operation. I also think Grumpy's idea is correct, just more on the cautious side. Whatever you do, if you have a powerful motor (over 300 ft-lbs across the powerband), then be sure you don't leave the stock tables as they were, or you'll go through transmissions like oil changes. The unlock, lock is all setup for stock cars.
