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Car Forum / Toyota / Toyota Cars / June 2007RAV4 Transmission Behavior Problem
Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. Problem - When the cruise control is used, the transmission downshifts/upshifts frequently when small inclines are encountered. If the cruise control is not used, the transmission does not shift in the same manner on the same inclines - in other words - if you maintain speed manually, the transmission does not hunt back and forth on minor inclines, but it does do this if the cruise control is used. Seems weird, but the behavior is so annoying my SO won't use the cruise control in many situations. Ed The Cruise reacts differently than your foot. Since it takes a bit longer to realize the changing conditions, it has to apply more gas to get the Set Speed back, and this makes a downshift out of OD. The speed returns and the shift back OD but the car can't keep the speed because the gear is wrong, so it downshifts out of OD again, and the process repeats. You can take control by shifting out of OD until you get to the top of the hill. The Cruise does not apply small amounts of gas as you do with your foot. It likes to apply full gas when if needs gas, and that causes a downshift. > Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. > Problem - When the cruise control is used, the transmission [quoted text clipped - 7 lines] > > Ed > The Cruise reacts differently than your foot. Since it takes a bit > longer to realize the changing conditions, it has to apply more gas [quoted text clipped - 9 lines] > foot. It likes to apply full gas when if needs gas, and that causes > a downshift. Thanks for the reply. I understand what you are saying, but the behavior is not normal (at least in my opinion). I am not talking about significant grades, just minor ones (like on I-40 from Raleigh to Wilmington NC). I've driven the same route in multiple vehicles and never had one react like the RAV4. I am thinking the control program is bad. The PCM actually controls the throttle position and the transmission gear selection. It sure seem like it could do a better job of controlling the situation. I was hoping there was a PCM code update that would fix this. My SO won't use the Cruise Control in may cases because it works so poorly. I have encouraged her to take it to the dealer, but she thinks that would be a waste of time. If my Ford acted like her RAV4, it would be at the dealer today. There is no way I would put up with the behavior (but then I would never have been satisfied with a I-4 RAV4). Ed >> Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. >> Problem - When the cruise control is used, the transmission [quoted text clipped - 7 lines] >> >> Ed my 06 camry 4 cyl does the same thing. just a slight grade on the interstate will cause it to downshift. love toyotas . they last forever but this is one thing that is anoying. the dealer will tell you this is normal. which it is for toyotas. theceuse control will matain the speed but will upshift and downshirt all the time. other than that how do you like your RAV 4? > my 06 camry 4 cyl does the same thing. just a slight grade on the > interstate will cause it to downshift. love toyotas . they last [quoted text clipped - 6 lines] > you > like your RAV 4? It is my SO's RAV4. She is very happy with the car in general. She mostly drives around town, so the cruise control issue is annoying but not a deal breaker. I spend lots of time on the highway, so I would find it a big problem. I have driven the RAV4 quite a bit and think it is a fine vehicle. My only complaints are wind noise at highway speed, mediocre seats and driving position (base model), and the worst control layout of any vehicle I have ever driven. It is like they had four different interior designers each trying to place the controls with no overall strategy - the panel dimmer control is where the mirror controls could be, the cruise control stalk thing is hideous, and the inside out HVAC control are ridiculous - but then if you drive the car a lot, you get used to it and my SO thinks the layout is fine. If I had bought the car, I would have gotten a V-6 AWD model with the better trim, but then I wasn't paying for it. Ed >> The Cruise reacts differently than your foot. Since it takes a bit >> longer to realize the changing conditions, it has to apply more gas to [quoted text clipped - 25 lines] > > Ed Increase your speed, or take off the OD. Generally, on my Toys, I have found that this behaviour stops at speeds over 65 MPH. Since most cops don't bother with you until you're over 70MPH, I set it to 68 and the problem goes away. >>> Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. Problem - When the >>> cruise control is used, the transmission downshifts/upshifts frequently [quoted text clipped - 6 lines] >>> >>> Ed >> The Cruise reacts differently than your foot. Since it takes a bit longer >> to realize the changing conditions, it has to apply more gas to get the [quoted text clipped - 15 lines] > the RAV4. I am thinking the control program is bad. The PCM actually > controls the throttle position and the transmission gear selection. But the throttle position given by your foot changes more gradually and starts sooner before speed has been scrubbed off, so the application of fuel is not as abrupt as it is with the Cruise. The Cruise is delayed, and it tries to give all of the fuel it can, therefore when it finally kicks in, the downshift is needed. Since I'm not in the car with you, it is difficult to tell what you are experiencing, but my instinct is that you are describing normal operation. When the car downshifts out of OD, then press the button to hold it there until you get over the hill. You _might_ be able to see if the linkage on the cruise is tight enough. This might improve the throttle response so that it looks to the rest of the car to be more like your foot. It sure seem like it could do a better > job of controlling the situation. I was hoping there was a PCM code update > that would fix this. My SO won't use the Cruise Control in may cases [quoted text clipped - 5 lines] > > Ed The two inputs to CC microprocessor are speed and RPMs. If you apply more throttle to compensate for the loss of RPM, as you ascend a grade, the tranny will not down shift as soon. The Japanese auto manufactures have a tendency to spin their engines higher, to attain HP for advertising purpose. The problem is that works fine on level ground where HP is doing the work but spinning the engines separates the tongue curve and the HP curve. Tongue is what gets you going and keep you going on a grade. The CC processor allows for some variations in RPMs, to a point, then downshifts, to get back nearer the torque curve, to pull the grade at the pre-set speed. You can prove it to yourself if you hold the throttle at a specific level and observe it downshift sooner than if you apply some throttle as you approach the grade. Nationally eight out of ten Camrys sold have the four, but around here Toyota dealers stock and sell more V6 Camrys, since the four is a slug in mountainous areas because of the poor torque at the proper RPM to stay in higher gears, thus adversely effecting fuel economy. mike > Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. > Problem - When the cruise control is used, the transmission [quoted text clipped - 7 lines] > > Ed > Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. > Problem - When the cruise control is used, the transmission [quoted text clipped - 7 lines] > > Ed I have a 2002 Rav4, does the same thing on even small grades if the rpm's are 2800 or so, 3000 rpm's and it holds overdrive in most instances. > > Problem - When the cruise control is used, the transmission > > downshifts/upshifts frequently when small inclines are encountered. If the [quoted text clipped - 9 lines] > I have a 2002 Rav4, does the same thing on even small grades if the rpm's > are 2800 or so, 3000 rpm's and it holds overdrive in most instances. > > Problem - When the cruise control is used, the transmission > > downshifts/upshifts frequently when small inclines are encountered. If the [quoted text clipped - 9 lines] > I have a 2002 Rav4, does the same thing on even small grades if the rpm's > are 2800 or so, 3000 rpm's and it holds overdrive in most instances. After reading your reply, I realized that I never really noticed much of a problem with the cruise control forcing downshifts (it is her compalinat) when I drive the RAV4 (mostly on trips down I-95). The big difference between my driving and the SO's is speed - I usually drive 5 to 10 mph faster than she does on the open road. I guess I am running the engine nearer the torque peak. On the other hand the SO, always gets 1 to 3 mpg better than I do... Ed > The big difference > between my driving and the SO's is speed - I usually drive 5 to 10 mph > faster than she does on the open road. Yup...that'll do it. Tell her to SPEED UP!!! ;) >> The big difference >> between my driving and the SO's is speed - I usually drive 5 to 10 mph >> faster than she does on the open road. > > Yup...that'll do it. Tell her to SPEED UP!!! ;) I agree with this. In our Sienna I often do not use the CC because it annoys me because it is more reactive and I drive more proactive with regard to speed. Tomes > Vehicle - 2007 RAV4 FWD (2WD) 4 cylinder, automatic. > Problem - When the cruise control is used, the transmission [quoted text clipped - 7 lines] > > Ed Are there any service lights illuminated? Scan the computer for intermittent failures. What speed are you trying to maintain when you notice the shifting? Is the vehicle covered under warranty? You may have a vehicle speed sensor malfunctioning or it's associated circuitry. The car is CAN compliant but the ECM controls the CC. It is a 4 cylinder so like others mentioned the torque is substantially less than the 6 cylinder. Small inclines should not make the transmission shift abnormally. |
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