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Discussion Starter #1 (Edited)
with cruise control engaged and starting on a decline the engine will oscillate about 100 rpm in a jerky motion when going downhill. I noticed this on my 1,700 mile drive to Oklahoma. I noticed it before but didn't really pay much attention because I didn't use cruise control that much. before I contact my dealer has anyone else had this problem.
 

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Yeah. They all do it. Much more noticeable in the automatics, but the manuals will blip the gas even going down a hill where the car is maintaining speed just coasting.
 

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This may be DFCO (Deceleration Fuel Cut-Off). On your way back, switch your car to Metric and monitor the instantenous fuel economy numbers. When they go to 0 L/100KM the car is in DFCO. There is a very slight jerk in my ECO MT when it enters and exits DFCO. Entering DFCO feels like a drop in power forcing you forward in the seat and leaving DFCO feels like a small surge in power. Monitor the jerkiness and see if it correlates to the instant reading changing to and from 0 L/100 KM. Note, the Cruze can enter and exit DFCO about twice a second while the DIC only updates once a second.
 

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If your describing surging RPM downhill with the cruise control more than one user has experienced this randomly with no known cause. My car has done this only a few times in 70K miles. I assume there has to be some reason for this(ac on or something), but I never could figure out what triggered it.

I typically don't use my AC but use my cruise control 99% of the time driving & never experience any weird behavior downhill. The RPM will drop slightly when you start downhill, and about 3-6 seconds after DFCO will engage and RPM drop about 100 more.

I should also add with the cruise set and in Drive(not manual mode), if your speed exceeds your set speed by 3mph, the transmission will downshift to 5th to try and slow your roll.
 

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Discussion Starter #5
Thanks for the feedback. Yes surging is a much better word to use to describe it. well mine does it pretty much all the time I certainly noticed it on the way here as my average speed was 69 miles an hour it didn't matter what percent grade the decline was either. I'll ask the dealer anyway it doesn't seem right none of my other cars do this. or have done if I should say. I'm okay if it happens every once in awhile or at least when just starting downhill but not all the time. in fact often I was disengaging cruise control cuz I didn't want to deal with it
 

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Put your car in M6 while on the highway. This may help alleviate some of the surging you feel by instructing the ECU to be less aggressive compensating for speed changes.
 

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Discussion Starter #7
Put your car in M6 while on the highway. This may help alleviate some of the surging you feel by instructing the ECU to be less aggressive compensating for speed changes.
Will do..... report to follow. In a month..... I am gonna be bored down here anyway so I'll stop by local dealer. Lotta cruze owners here in okc
 

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Mine does this every day when I go down a hill with cruise control on. I always assumed it was normal because my speed never changes. I have a 2014 2LT with the 1.4. My guess is that it's the engine braking.
 

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I haven't noticed this in my diesel which has the 6T45 transmission as opposed to the 1.4's 6T40. Maybe the extra engine braking of the diesel prevents this?
 

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I use cruise control so much that my button is getting worn. I haven't noticed this in the 24k km I have so far. Oops nvm, mine is a diesel. Sorry, didn't notice on the app which section this was in


Sent from the sexy electrician
 

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Put your car in M6 while on the highway. This may help alleviate some of the surging you feel by instructing the ECU to be less aggressive compensating for speed changes.
Not sure about in the US but in my owners manual it says cruise control won't work in manual mode.
 

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I have never had a problem with cruise control so I have never tried it in M.
 

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I noticed the jerkiness prior to replacing my turbo charger in my 2011 Chevy Cruze RS Turbo (71,000 miles). I am now currently experiencing my car cruising in 2,700 RPM at 70-73 MPH on the highway. To me this number seems to be high, but not sure if others are at or near this amount of RPMs.
 

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I noticed the jerkiness prior to replacing my turbo charger in my 2011 Chevy Cruze RS Turbo (71,000 miles). I am now currently experiencing my car cruising in 2,700 RPM at 70-73 MPH on the highway. To me this number seems to be high, but not sure if others are at or near this amount of RPMs.
Normal.
 
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