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Hello! I have a 2011 Chevrolet Aveo5 LT with a 1.6L Ecotec engine and a 4AT. Vehicle has 55k miles on it and ih has been fairly reliable. At 52k i change the sparks, air filters and a Gunk gas treatment. I’ve noticed that while drivingnat a stable speed, for example, 50mph at 2k rpm, the car slightly revs up and down. Not violently revs, no check engine lights, nothing. It idles super smooth and accelerate nicely. It does it while driving at cetain speeds at certain conditions. Any ideas what could it be? I thought maybe cleaning the throtle body? Seafoam? Or a vacumm leak? Also, gas mileage is very crappy at 22-25 mpg overall. One tank gives me 250-280 miles. I read it was usual on this vehicles. Thanks for the help!
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[quote=”ralph0722″ post=89784]Hello! I have a 2011 Chevrolet Aveo5 LT with a 1.6L Ecotec engine and a 4AT. Vehicle has 55k miles on it and ih has been fairly reliable. At 52k i change the sparks, air filters and a Gunk gas treatment. I’ve noticed that while drivingnat a stable speed, for example, 50mph at 2k rpm, the car slightly revs up and down. Not violently revs, no check engine lights, nothing. It idles super smooth and accelerate nicely. It does it while driving at cetain speeds at certain conditions. Any ideas what could it be? I thought maybe cleaning the throtle body? Seafoam? Or a vacumm leak? Also, gas mileage is very crappy at 22-25 mpg overall. One tank gives me 250-280 miles. I read it was usual on this vehicles. Thanks for the help![/quote]
Since it still should be under warranty, I would take it back to the dealer…
Here are my thoughts… Throttle by wire is not my favorite thing… It gives me a detached feel of driving and is noticeable… I trust that engineers will make it better in the future, but for now it is what it is….
My 2 cents…
Perhaps your throttle by wire is having an issue with electronics… perhaps the throttle body is dirty…If you clean it, be careful not to disturb the butterfly valve or else you may be in for a trip to the dealership to reset the position sensor….
The poor gas mileage may be explained by a winter blend of gas (I average 3-5 less MPG on winter blend)… Many of us suffer from this… Especially if you live in a cold climate and let the vehicle warm up in the morning unattended….
I would think a vacuum leak would manifest itself with a CEL or another way, but still check..
Yes, I’ve read that care needs to be used when cleaning electronic throttle bodies. I didnt even noticed i still have warranty! 5yrs 100k i looked it up! Thanks for that tip! I’ll look more into it.
Another thought that I had was possibly the transmission going in and out of lock up, but I think that’s remote. I’m with ToyotaKarl, if it’s still under warranty, take it in. Even if they don’t find anything you’ll have it documented so if it gets worse in the future, you’ll have record of reporting it while it was still in the warranty period.
Keep us posted.
I agree with Eric that the torque converter could be slightly locking/unlocking at certain speeds. It’s likely that the “egonerds” at the dealer won’t listen but mention it anyway.
[quote=”EricTheCarGuy” post=89848]Another thought that I had was possibly the transmission going in and out of lock up, but I think that’s remote. I’m with ToyotaKarl, if it’s still under warranty, take it in. Even if they don’t find anything you’ll have it documented so if it gets worse in the future, you’ll have record of reporting it while it was still in the warranty period.
Keep us posted.[/quote]
Thank you! You think that may explain the horrible fuel economy also? Friday 2/28/14, i filled up the tank. Took 10 gallons. I drove 30 miles running errands and i noticed the gas gauge moved down to 34. Out of curiosity, today 3/1/14 i went to the gas station and filled it up again. Took 2 gallons. In one afternoon burned 2 gallons for only 30 miles of driving! Thats 15 mpg city driving! In orlando? Flat state, no hills. No snow. 🙁
[quote=”ralph0722″ post=89980][quote=”EricTheCarGuy” post=89848]Another thought that I had was possibly the transmission going in and out of lock up, but I think that’s remote. I’m with ToyotaKarl, if it’s still under warranty, take it in. Even if they don’t find anything you’ll have it documented so if it gets worse in the future, you’ll have record of reporting it while it was still in the warranty period.
Keep us posted.[/quote]
Thank you! You think that may explain the horrible fuel economy also? Friday 2/28/14, i filled up the tank. Took 10 gallons. I drove 30 miles running errands and i noticed the gas gauge moved down to 34. Out of curiosity, today 3/1/14 i went to the gas station and filled it up again. Took 2 gallons. In one afternoon burned 2 gallons for only 30 miles of driving! Thats 15 mpg city driving! In orlando? Flat state, no hills. No snow. :([/quote]Sorry for the late update, been going through some personal issues. Ok took the Aveo to Chevrolet dealership for service. It has 60k miles on it now. Had a transmission flush, oil change and tire rotation. They inspected the car and, of course, they could not locate te source of the hesitation. They recommended clening the throttle body for a lovely 159.00. I told them, maybe next time. I stopped at Walmart and bought a bundle pack of CRC throttle cleaner and MAF sensor cleaner for 8 dollars. A Walmart branded gas treatment bottle for 1.88. Yesterday i took apart the intake air box and hose that goes to the throttle body. The throttle plate and walls were all covered in black sludge. Being careful not to manually open the butterfly (electronic throttle you cannot open them manually), I had a buddy turned the ignition switch on the ON position and depress the accelerator. Removed all the black gunk from the throttle plate and body. Cleaned the MAF sensor. Put everything back and took the car for a test drive. Gremlins GONE!!!! No hesitation. No choking. That was the problem. Throttle body was dirty with sludge. Fixed for under 10.00 dollars.
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