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Discussion Starter #1
i just bought an 06 access cab 4wd trd off road. it is my second taco. i previously owned a 95 with the 3.4 and never had any problems . went through 3 fords and now im back. i got the automatic and was wondering what was with the tranny downshifting when you apply the brake while going down a hill. just wondering if it does it by speed or by applying brake a certain number of times.
pretty satisfied with gas milage so far i got 19 and then 17 but with some city driving. was wondering what everyone else likes about theirs. ilove the 5 spd auto. i wouldve got the 6 spd but the auto was so smooth and i drive a big truck all the time and thats 10 gears there. but the 5 seems like its always in the power range since there is an extra gear.
 

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Discussion Starter #3
yeah i thought so too, but couldnt find anything in the owners manual. just the DAC and engine braking by physically putting it the lower gear.
 

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I've noticed it too, even if I'm on flat surfaces. Though it's usually when I let off the accelerator and before I apply the brake.

I like my truck, except the cruise control. At the sign of the slightest incline, the truck kicks down a gear (or two) and the accelerator mashes to the floor. I drove a Ford Contour that would make it almost all the way up some hills before kicking down. Essentially, my cruise control is worthless to me. I've been getting about 17 mpg highway (East Texas hills.) Not sure on the highway, I'll figure that one up this weekend.
 

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BlackBetty said:
I've noticed it too, even if I'm on flat surfaces. Though it's usually when I let off the accelerator and before I apply the brake.

I like my truck, except the cruise control. At the sign of the slightest incline, the truck kicks down a gear (or two) and the accelerator mashes to the floor. I drove a Ford Contour that would make it almost all the way up some hills before kicking down. Essentially, my cruise control is worthless to me. I've been getting about 17 mpg highway (East Texas hills.) Not sure on the highway, I'll figure that one up this weekend.
I agree with you on the cruise control. Even when you resume cruise and it only has 1 mph to make up, the damn thing goes into flog mode and downshifts twice and redlines the motor. It's friggin' stupid. It surprises me that it is so crappy when the technology to fix it has been around for so long. If I had access to the program, it would not be difficult to retune it to work better. PID controllers are not rocket science.
 

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Most cruise algorithms are proportional only - with a fairly high gain to reduce any offset. You can usually get away with that as you are cruising in a high gear and liberal applications of throttle will not increase speed very quickly.
Given those reactions it does sound like it needs the gain softened and some integral added to bring it back to setpoint. You certainly wouldnt need any derivitive.

Ive got a manual trans, and my cruise works really well - although obviously it cannot shift gears - but it might be hurting gas mileage if its adding alot of throttle. Likely though the algorithms are different for manual vs. auto trans.
 

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Discussion Starter #7
bluzharp said:
I agree with you on the cruise control. Even when you resume cruise and it only has 1 mph to make up, the damn thing goes into flog mode and downshifts twice and redlines the motor. It's friggin' stupid. It surprises me that it is so crappy when the technology to fix it has been around for so long. If I had access to the program, it would not be difficult to retune it to work better. PID controllers are not rocket science.
or even when you want to accell a couple mile an hour. i just tried it with no cruise on the way home on the interstate and it stayed in fifth but came out of lockup on the hills. id expect that though.
 

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Sort of off-topic, but cruise control should have two "settings." The first works like we're accustomed to, you set a speed, and that's it. The second would be a bracket. Say you don't want to go slower than 65 and no faster than 75. You set it and that's it. Then, in changing elevations you wouldn't have the kick for dropping 1mph below cruise that you get now.

I will say, this is the first vehicle I've ever driven that behaved this way. Every other vehicle I've driven over a long-term would loose speed, try to keep in the same gear, and then finally downshift whenever they were ~5mph under the cruise speed. Granted, these were all Fords, so maybe it is something they're doing.
 

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Discussion Starter #9
BlackBetty said:
Sort of off-topic, but cruise control should have two "settings." The first works like we're accustomed to, you set a speed, and that's it. The second would be a bracket. Say you don't want to go slower than 65 and no faster than 75. You set it and that's it. Then, in changing elevations you wouldn't have the kick for dropping 1mph below cruise that you get now.

I will say, this is the first vehicle I've ever driven that behaved this way. Every other vehicle I've driven over a long-term would loose speed, try to keep in the same gear, and then finally downshift whenever they were ~5mph under the cruise speed. Granted, these were all Fords, so maybe it is something they're doing.
i would be nice if there was a happy medium in there. i used to have fords and that was one of the things i couldnt stand. you had to put them to the floor to downshift.
 

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The cruise controls on these Tacomas just aren't right. I'm sure it's just a matter of programming (I hope). When I set mine, often the speed will drop 3-5 mph and then it will kick down and accelerate over the desired speed. If I do this on even a slight incline, the truck will downshift two gears. I'm 59 and have owned a lot of vehicles and never had anything like this.

I've notice that I can go up the same hills I normally travel without cruise on and the transmission won't downshift. Heck, I've got a 1972 Grand Prix who's cruise works light years better than the Tacoma's. So much for progress.

I wrote a complaint to the NHTSA: http://www-odi.nhtsa.dot.gov/ivoq/

Can't hurt and maybe Toyota will eventually come up with a fix.

WyoBob
 

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Discussion Starter #11 (Edited)
5-4 downshift

the 5-4 downshift is starting to get annoying. i started down a hill today and was going between 35 and 40 and let of the gas just to coast at about 1500-2000 rpm and it just downshifted without hitting the brake and went up to 3000 rpm and had to get back on the gas a little to get it back out of 4th. i wonder if there is a way around it or if mine shouldnt be doing that.
also ive seen different posts on gas mileage but not alot of people said what mileage they were getting with what grade of fuel. i just wondered because mine has been getting steadily worse. ive gone from 19 to 14.5 with 87. but its being blended in with whatever the dealer put in because i filled up 3/4 of a tank and then again at 1/2 tank.
 
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