Possible Throttle body issue on 2010 Aveo?

Hey guys,

I may have a throttle body issue with my 2010 Aveo. Here's the story behind why I think so, and I'm hoping someone may be able to help identify the problem.

So, originally I drove a 2009 aveo, which I was given after my brother bought his own car. It had been through a lot, and my dad said that they replaced the ignition coils 3 times, replaced the throttle body once, along with many other things. But once he bought his own car, I was given the aveo, and it seemed to be running great. I would typically squeeze 38-40 MPG out of it (it was the manual version), and it really never gave me issues. I loved it, but unfortunately I got hit in an accident where someone blew a stop sign and ruined the driver's side of my car. We had to buy another car. So, since I loved that car so much, we bought a 2010 Aveo (manual again).

I didn't notice anything funny about it during the test drive, but once we took it home I started noticing some things. First of all, it will buck in any gear at either the 1500 rpm range or around 1800 rpms. But it will only do so if you have the throttle in the right position, it seems to be if you lightly touch the pedal. It will do this in any gear, so I don't believe it comes from lugging the engine. Also, what is odd about that is that if you either let out the pedal, or push harder, the bucking stops. Also, the response time of the throttle is kind of slow. I noticed I would stall this car a lot, which is very unusual for me as I've been driving manual for so long. I realized that the pedal takes about a whole second before anything happens. So, I've adjusted my driving to work with it. What would happen is if I let out the gas and pushed the clutch in consecutively, like I've always done, the engine will jump up about 500 rpms, then slowly drop resulting in a rough shift unless you wait a long time. So, what I've been doing is letting out the gas, waiting about a whole second, then pushing the clutch in. And also pushing the gas pedal in way before I normally would when starting from a stop. The third issue I've noticed is how if you step on it, the car just drives odd in general. It feels like it doesn't just rev straight up, it almost feels like it revs up and slightly back down as it moves up the rpm range. For example, one time in traffic I had to get up and going, so I really stepped on it in first and the car had a very subtle bucking feeling, which is what makes me think that was happening. Also, I haven't been able to squeeze more than like 33 MPG out of it at best! I'm just not sure why it drives so different than the other Aveo we owned.

Since we've owned this new Aveo, we took it to a local shop for a tune up and they replaced the ignition coils. However this didn't fix most of these problems. The only thing it helped is that it idles a bit better now, and they claimed it was misfiring so I suppose that is taken care of. However it still bucks in any gear at either 1500 or 1800 rpms with a light touch on the pedal, it still isn't getting the mileage I was used to getting (I'm very conscious of how I drive, that's how I would squeeze 40 MPG out of the 2009 aveo) and also, it just doesn't feel right. Like I said, it doesn't seem to rev right up, it feels like it kind of revs up and down subtly as it makes its way up.

I also cleaned the MAF sensor just because it is easy to do and supposedly a dirty MAF will result in that slow response time. It again helped the idling, but not the driving. That is why I think it is the throttle body that needs to be replaced.

So, I'm wondering if any of you on here have dealt with a similar issue in your Aveo, or if you could help me to identify the problem? Also, I've heard you can clean the existing throttle body which may help. Should I try this first, and if it still doesn't help, then replace the throttle body?

Thanks!

EDIT: Also, I did some research prior to posting this, and people were saying that Aveo's doesn't have a serviceable throttle position sensor - that you have to replace the whole throttle body. Is that true even with a 2010 aveo? I'd rather replace or clean small parts first before spending $170 on a new throttle body if that doesn't help.

Replace the upstream O2 sensor. My 09 did the bucking thing and that was what fixed it.

Not sure about the throttle response problem

Could be bad Or sensor, possibly carbon buildup in throttle body, or b ad gas. Try a few tanks of premium gasoline and a bottle of dry gas to remove water.

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Originally Posted by EAD15

Replace the upstream O2 sensor. My 09 did the bucking thing and that was what fixed it.

Not sure about the throttle response problem

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I'll look into it, it seems like that sensor may be pricey? I also realized today while driving it will buck really at any rpm if you press the gas pedal at the right spot. I had it bucking at 2500 rpm in 3rd today, so that's definitely not from lugging the engine. Thanks for the help though!

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Originally Posted by kittysniper454

Could be bad Or sensor, possibly carbon buildup in throttle body, or b ad gas. Try a few tanks of premium gasoline and a bottle of dry gas to remove water.

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Well, I've only been filling it up at the same places I used to always fill up with my other car. However, I have no idea what the person before me did. So you mean fill it with premium gas a couple times and see if that helps? Then clean the throttle body if not?

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Originally Posted by StarbardGuitar

I'll look into it, it seems like that sensor may be pricey? I also realized today while driving it will buck really at any rpm if you press the gas pedal at the right spot. I had it bucking at 2500 rpm in 3rd today, so that's definitely not from lugging the engine. Thanks for the help though!

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If it's doing it at only a specific pedal position (and always the same position), it could be the accelerator pedal position sensor. That would probably also explain slow pedal response.

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Originally Posted by EAD15

If it's doing it at only a specific pedal position (and always the same position), it could be the accelerator pedal position sensor. That would probably also explain slow pedal response.

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This is what I originally figured was wrong and was looking for validation of that or another idea. I read though, that with the Aveos that you can't just replace the throttle position sensor, that you have to replace the whole throttle body. Would you happen to know if that is true?

What is weird about the bucking is it seems to do it the worst around 1500 and 1800 RPM, as per my original post - but I did recently realize it seems to be possible at any engine speed. For whatever reason though, it happens more often around those lower RPM's. Should I try and clean the throttle body first? And then if that doesn't work replace it? Thanks for your help!

Quote:

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Originally Posted by StarbardGuitar

This is what I originally figured was wrong and was looking for validation of that or another idea. I read though, that with the Aveos that you can't just replace the throttle position sensor, that you have to replace the whole throttle body. Would you happen to know if that is true?

What is weird about the bucking is it seems to do it the worst around 1500 and 1800 RPM, as per my original post - but I did recently realize it seems to be possible at any engine speed. For whatever reason though, it happens more often around those lower RPM's. Should I try and clean the throttle body first? And then if that doesn't work replace it? Thanks for your help!

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I wasn't referring to the Throttle Position Sensor. The US 2009 and 2010 (maybe other model year aveo's too) cars are "drive by wire" which means there is no cable connecting the gas pedal to the actual throttle. There is a sensor on the gas pedal that tells the computer how far you have it pressed and the computer decides how far to open the throttle.

If the sensor on the gas pedal is malfunctioning, the computer could be getting erroneous data and acting on it causing your issues. Unfortunately, the position sensor only seems to come as part of the accelerator pedal assembly and looks to be around $140, new. Fortunately, it is only 3 bolts and a connector to replace.

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Originally Posted by EAD15

I wasn't referring to the Throttle Position Sensor. The US 2009 and 2010 (maybe other model year aveo's too) cars are "drive by wire" which means there is no cable connecting the gas pedal to the actual throttle. There is a sensor on the gas pedal that tells the computer how far you have it pressed and the computer decides how far to open the throttle.

If the sensor on the gas pedal is malfunctioning, the computer could be getting erroneous data and acting on it causing your issues. Unfortunately, the position sensor only seems to come as part of the accelerator pedal assembly and looks to be around $140, new. Fortunately, it is only 3 bolts and a connector to replace.

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Oh, okay. I figured they were the same thing? I'll look into it a little more. Thanks!

So, I went to clean the throttle body, and it was pretty dirty. However, this is it "wide open" I kept some weights on the pedal with the key "On" so that it would open and close the body for me, and this was it with the pedal to the floor. I even asked my dad to come in quick and step on the pedal so I knew it was to the floor. Same thing, it would move, but that was it all the way open. That just seems odd to me, I would think it should open a lot more than that? I could only clean out some of the gunk. However, the little bit of cleaning I did helped a lot more than I expected. It is a lot less slow to respond to the pedal, but still a little off. Is the throttle body supposed to open more than that? I'm really thinking now for sure the TB is the issue.

http://i62.tinypic.com/6ghqbl.jpg