Running rough

[Loopy84]

My 08 aveo sputters and runs rough when cold. I can't seem to figure out why, and only seems to be at idle. Once the engine gets up to temp it runs like a top. So far since I've gotten it I've replaced the air intake temp sensor, coil pack, plugs and wires as well as a new air filter. I've also sprayed out the throttle body with throttle body cleaner. Any ideas would be welcome!

[09aveo5-LS-5SP]

My 08 aveo sputters and runs rough when cold. I can't seem to figure out why, and only seems to be at idle. Once the engine gets up to temp it runs like a top. So far since I've gotten it I've replaced the air intake temp sensor, coil pack, plugs and wires as well as a new air filter. I've also sprayed out the throttle body with throttle body cleaner. Any ideas would be welcome!

Check the wires going into the plug from the harness wire a lot of times the insulation cracks and exposes the wire. Also, check O2 sensor plugs VVT plugs along with headlight plugs check almost all the plugs basically to all your sensors, they tend to crack and expose the wire which can short and cause issues.


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[Loopy84]

But then why would this only cause an issue until it warms up? I could see the 02 though as it has a small exhaust leak

[09aveo5-LS-5SP]

Check the wires going into the plug from the harness wire a lot of times the insulation cracks and exposes the wire. Also, check O2 sensor plugs VVT plugs along with headlight plugs check almost all the plugs basically to all your sensors, they tend to crack and expose the wire which can short and cause issues.


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Check your local dealership and give them your vin maybe a recall as well maybe


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[09aveo5-LS-5SP]

But then why would this only cause an issue until it warms up? I could see the 02 though as it has a small exhaust leak

Also check your spark plug gap 09aveo5 was originally.44 from factory then ign coil pack on it originally recalled


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[Loopy84]

I replaced the coil pack and plugs and wires

[09aveo5-LS-5SP]

Map sensor maf sensor iat sensor.

Or what about the VVT solenoids


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[sjcleckley1]

08 and below does not have VVT 09-11 does, could you have some dirty injectors? have you run some cleaner in the gas I use Beryman's B12 once in a while cheapest at Walmart and has about what all the other more expensive ones have look at the chemicals in them, when my car (08 was cold at times it would be hard to start or falter and rough idle a while in the winter time not really the cold in Arizona but could be around 45 and below 32 once in a while and that would fix it do you have a scan tool I had to buy one to check my car out was always borrowing one, I ended up getting a Bluetooth on from Autel ApMax Ap200 for around $45 shipped, when working on any FI I always verify fuel pressure first then the fuel trim.

on the 08 you can reset the ECM by disconnecting the battery or anytime the battery is disconnected it's reset, so it has to go through a relearn on idle control you have to start it up let it idle till completely up to temp put it in every gear and back to park then put on the ac and off and do it again with each gear and ac do it when the car is as cold as possible after cleaning the fuel system make sure to do it when you are going to drive the care some distance or us it when you have a low tank and drive it some than refill as those cleaners are hard on the plastic and rubber parts don't let sit in the tank a long time I'd go an a 50 mile drive

[Loopy84]

Thanks much I'll give it a go. I do have a cheap scan tool but the best I'll get I believe is clearing the codes if any. Last i checked it didn't have any more codes though. Didn't know about the relearn though. So turn ac on then off and then put into each gear and while in gear turn ac on then off and then proceed to next gear?

[09aveo5-LS-5SP]

Thanks much I'll give it a go. I do have a cheap scan tool but the best I'll get I believe is clearing the codes if any. Last i checked it didn't have any more codes though. Didn't know about the relearn though. So turn ac on then off and then put into each gear and while in gear turn ac on then off and then proceed to next gear?

If you know somebody with a scan tool where they have a little bit more access to the controls of the ECM you can shut down each injector one at a time. See how the idling operates Siri turn one off wait about 30 seconds then if there’s no change, then that would be the issue, but if it starts bogging, then you know the injectors working the way it should. Also, I believe some of the O2 sensors on certain models actually need to be programmed for the emissions as well, which can cause rough, idling, and issues.


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