RPM's pulsing, over revving at HWY speeds?
 

Sorry guys if this has been addressed, wondering if this is a known issue before I bring it in....here's the scenario.






Usually only happens when Im at highway speeds, specifically 75-80mph. Flat roads, no hills, and im usually using cruise control


...so cruising at a nice 2500 rpms or so, then every once in a while, with no extra throttle or anything, it will rev up high to like 3100 rpms, then drop back down.. it's weird, and a little scary. Transmission? Engine? I keep up with regularly scheduled maintenance, so Im hoping it's nothing huge.










Thoughts?

So if you engine revs up to 3100 does you speed go up proportionally?

No. That's the odd part, I can feel it, but no speed going up. It's like its a minor slip of some kind.

Has it ever happened without using cruise control?

Yes. I thought it was my foot doing it, like if I hit a bump and it made me press the gas a little harder, so I tried it with cruise to eliminate that theory, still does it. I should take a video of it and post it somehow. -Jason

Well that's not good. If you can replicate it and take a video, I would take it to the dealership to see whats going on. This is not normal, at least not with my car anyway. Worst case is it could get worse over time and the rpm's might not come down.

The CVT fluctuating rpm's at a steady speed (cruise on or off) is a well-documented thing. It is continuous, part of the how it is programmed and isn't harmful. LARGE fluctuations like this probably aren't normal. My 2010 with 140,000 miles on it has done it since new. Normally fluctuation on a repetitive and continuous basis (every 2-3 seconds) of 75-125 rpms or so is normal. Occasional wide fluctuations of up to 200-250rpm is not uncommon. Fluctuations of 500-600rpms probably does need to be checked.

The CVT has a positive feedback loop. The TCM commands the line pressures on the drive and driven pulleys to provide specified gear ratio. However, TCM then compares actual gear ratio to commanded gear ratio and adjusts line pressure to produce desired ratio.

May want to get it checked out - might be indicative of wear in the transmission or problems with the valve body.

Let us know what you find out. Curious about this.

Late,
Travis

Thanks guys. I'm probably exaggerating with the 600 revs jump, probably 2-300 in actual #s. Just weird that I'm just noticing it now.

I find that headwinds at highway speed will do exactly this on my car. Annoying if you are driving for hours with cc on. Last time I locked it into 6 manual and that settled it down.