Problems with acceleration while using Cruise Control?

[mexigrl]

Hi -I love my new Salsa 05 Vibe but it has one issue that is driving me crazy!When I am driving with cruise control on and I approach a hill (even just a slight incline) the RPMS jump up and run hard and then back down. It seems crazy because I live in MS (not exactly hill country!). It would seem that having Cruise Control isn't even worth it if it's going to run like crap when I use it. My previous car was an 01 Accord and I never once had this revving up problem.Is this just the price I pay for buying the Vibe? OR...could there actually be something wrong that is causing this?Thanks for your input!!Mexigrl

[ragingfish]

If the car can't get enough power in the O/D gear to make it up the hill, it will downshift to 3rd to get extra power to get up the hill. It is completely normal.Your accord may have had different gear ratios and/or a different engine which may have been able to supply sufficient power without downshifting.You can "help" the car make it up the hill by finessing the pedal as you go up the hill. If you provide the car the extra oomph before it needs it, the momentum could be enough to get it over the hill without downshifting.

[zionzr2]

thats the problem with a tiny engine in a heavier car.

[jake75]

I do not think it is any different than if you had manually dperessed the accelerator to maintain speed going up the hill. With the cruise it can drive you nuts so when driving in the mountains I avoid using cruise. And it happens in more powerful cars as well, e.g. my 3.3L T&C SWB van.

[ColonelPanic]

The guys are right on the money. Sadly, a combination of factors cause the particular behavior you have been experiencing. We've got a heavy car, with an engine that is too weak to deal with all the weight, and programming with the computer that encourages the cruise to become violent when it senses you're slowing down. Thus, your transmission will shift out of 4th and into 3rd when going up a hill, and if the grade is steep enough, it will downshift again.Mine does the same thing, and it's safe to say everyone else who has a base/automatic and maybe the AWD guys too are experiencing this. I've not had too many issues with this on other cars I've owned - they did downshift as they should when going up a hill when it senses you're losing some speed, but they never went postal like the Vibe tends to do... That's due to those cars having significantly higher engine output...The best way I've personally found to deal with this is to just cancel the cruise right before you start to climb the hill and keep the throttle steady. Give it just a tiny bit more gas if you don't want to lose too much speed. Set it again once you've reached the top. That seems to work best for me - and probably helps fuel enconomy in the process.

[djb383]

In addition to the engine power factor, I think it has something to do with the programing of the PCM. Every now and then on my '05, when in cruise control mode, the torque converter will unlock but the tranny will stay in 4th gear when negotiating an incline. When the converter unlocks, engine rpm will increase by 300-400 and that is enough extra power to make it to the top of the incline versus the 1400 rpm jump when the tranny both unlocks and shifts from 4th to 3rd. Obviously a 300 rpm increase isn't near as abrupt as a 1400 rpm increase. It seems to me that the PCM could be programed to first unlock the converter and hold that mode for a second or two, then if even more power is needed, shift to 3rd. Just my $0.02.

[eilros]

The exact same thing happens in my '04 Vibe and it drives me crazy. It happens on every single hill, no matter how small. I'm glad to hear this is "normal" though.