Possible Throttle body issue on 2010 Aveo?

[EAD15]

In my 09, with the car off and the accelerator pedal pressed to the floor, the computer only commands the throttle to 40%. I'm not going to tear down to my throttle to double check, but that looks like 40ish to me

[StarbardGuitar]

Okay, that makes sense to me. Should I completely remove the throttle body to clean it, so I can open it fully?

[EAD15]

At this point, I'm guessing it couldn't hurt. I've been digging through the factory service manual (for the 09) for suggestions but I'm not coming up with anything simple to test.

This may be one of those situations where taking it to a competent shop might be the best option.

[StarbardGuitar]

I took the throttle body out and cleaned it all out very thoroughly. It drives a lot better, but the gas pedal is still just slightly slow to respond. It responds quicker to the pedal being pushed in, but still hesitates for a slight bit after the pedal is taken out. It's nowhere near as bad as it was, so I'm much happier. It also feels like it gained a little power back. My dad noticed that this car seemed less powerful than the '09 we owned previously. However, before I cleaned it out we wanted to see if the throttle would open all the way when the engine is running and the pedal is put to the floor. I took a video of it to show you, because my dad thinks (he worked a lot on much older cars when he was younger, and never works on our newer cars) that it should open wider and that there might be something wrong with it. I'm just wondering, is it supposed to only open this wide? And also, I'm not sure if you can see in the video, but when he lets out the gas, it revs down really slow, and the plate doesn't just close - it very subtly closes and opens up again a little as it makes its way down. Just curious what you think of this? Thanks!

[Mischif]

Hey starboard, i have a 2011 chevy aveo that im working on for someone. It feels real sluggish and revs down slow like you stated your 2010 does. So i first data logged the car, everything seemed fine EXCEPT the ignition timing advance was really really low. Im talking it idles right around 0 degrees advance. accleration and cruise timing advance numbers don't look right either. So its obvious the sluggishness and bad throttle response is due to the overly retarded timing. So i checked the timing belt and its aligned correctly. So something is causing it to run retarded timing. Unless thats how they programmed this thing to run low timing like that, but i seriously doubt it. So i hit the web and started researching. Not alot of info on the newer models, like what base timing should be at idle ect. Anyway i stumbled onto your thread and seems like we have the same issue. I did notice that my throttle body was real dirty while doing the timing belt. So next im going to check to see if my throttle body acts the same as yours. To answer your question no your throttle body should not be doing that. The throttle body should be able to go WIDE OPEN THROTTLE when you push the pedal down all the way regardless if its drive by wire or not. And it should snap shut fast when you release the pedal. If you want to know how much your plate should open up when WOT just push on it with your finger to open it up until it wont no more.

I'll report back to let you know if the throttle body on the aveo i have is doing the same as yours. Also you have a way to log the ecu? Could be helpful to know what your ignition timing is looking like.

[StarbardGuitar]

Thanks for the reply, if this helps you at all with the car you are fixing - I cleaned the throttle body and gained back some power as well as around 4 or 5 mpg's and a little bit of pedal response time. However, the pedal still responds a little slow, like when I go to start I have to push the pedal in a little ahead of when I would in other cars to not stall. It is most noticeable when shifting, as it responds slower when I am accelerating faster (with the throttle more open). Basically, if I accelerate extremely slow and barely push the gas pedal, when I take my foot off the gas to shift, you can feel it almost immediately. But if I have to get up to speed quick (getting on the highway for example) and I push on the gas harder, when I take my foot out to shift, it takes almost a whole second before you can hear or feel that it realizes I'm no longer pushing the gas pedal. So I think my problem is in my throttle body or maybe a sensor. I also bought a cheap OBDII code reader but I don't know if that can read the ECU like you said. What would I need to read the timing?

[PoisonIvy]

I have a ScangaugeII mounted in my 2010. I know it reads ignition timing. So when I'm out later tonight I'll see if I can make sense of the timing for each situation.

[Mischif]

A scan guage that can read live data, or a laptop and a $10 elm327 from ebay.

I dont envy you, having to drive this car around with a manual transmission. I've never driven a drive by wire manual before, but judging from the auto drive by wires i've driven, i would absolutely hate it. Even on the good setups that respond quick, i can still feel a lag that is very noticeable to me when you press the gas, and then actually feel a response.

So i checked out my throttle body, acts exactly how you described yours acting. So i threw the front end up in the air and hooked the computer back up. With the pedal floored, and reving it all the way to red line...interesting data. Pedal see's 85% which id say is acceptable, ecu sees command for full throttle....but it doesn't activate the throttle body completely. When all the way on the pedal the ecu is only opening the throttle to around 70% for a split second and then starts closing the throttle as it contiunes to rev. Dont know what to make of that. I can see how cleaning the throttle body helps a little. Since something is limiting how much the throttle plate opens, that extra air flow you'll get back from a clean throttle body makes a notable difference.

I want to say im 100% sure its the throttle body but im starting to think maybe the ecu might need to be recalibrated/flashed or this is just a piece of junk from the factory engineered to be a turd.

[Mischif]

Okay so spent all day digging into this. Figured out the pinout for the throttle body.


harness side looking at pin end from left to right top to bottom (top side has release button)

Violet/purple - 5v power supply for sensors
dark blue - Throttle plate dc motor +
light brown or tan - Throttle plate dc motor -
Brown w/ black stripe - tps2 signal to ecu
light blue or sky blue - Ground
white - Tps1 signal to ecu

Tested the throttle body by disconnection the harness and jumping the pins that corresponded to the dc motor, straight to the battery. Snapped COMPLETELY open right away. So throttle body is good. Gonna see what else i can find out.

[StarbardGuitar]

Thanks for the updates! I'm curious as to what you'll find is causing these problems and maybe that will help me with my car.