2008 starts in the cold - won't keep running

[Ehwick]

Hi everyone, I'm new here and more than a little frustrated. I have a 2008 Aveo5 LS hatchback that seems "cold blooded". During most of the year the car runs OK. However, once the temperature gets below 35-40 degrees I have problems. The car will start up just fine with no issues or funny noises. But, after a minute or two (just enough time to get out of the car and start scraping the ice off the wind shields) the car shuts off. It acts as if I turned the key off. But here's the kicker, the start will crank over but the engine doesn't fire. I can come back a few hours later and the car starts again. But if the temperature is still below 40 it will again shut off and not fire up. I know it has to be something electrical, because once I disconnect and then reconnect the battery, the car will fire up again. However it still will shut down if its too cold outside. Any ideas? a sensor? computer reprogramming needed?

Thanks - Eric
"Ehwick"

[xintersecty]

Do you get any engine codes? Strongly suggest that you get ODBII reader. If you have a smart phone use Torque in combination to a ODBII to bluetooth scanner.

[Ehwick]

Do you get any engine codes? Strongly suggest that you get ODBII reader. If you have a smart phone use Torque in combination to a ODBII to bluetooth scanner.

I don't have a reader but I have taken it to a garage after this happened last year. They weren't able to collect any codes. They suggested that the codes were lost because I had to disconnect the battery after the event so I could start the car.

[avguy]

One minute of cold warmup is right in the ballpark time for the ecu to close the loop, so there's one very quick and easy test you can try, in order to see if this is closed loop-related. Just remove the upstream O2 sensor connector before doing the first cold start. That will force the ecu to stay in open loop, and you'll find out if it will keep running in that mode. If it stays running, then the issue is something which participates in closed loop processing.

But if it still stalls the same way with the sensor disconnected, then confirm it's not being starved for fuel by spraying a small bit of carb cleaner into the intake, right at the time it begins to stall.

[Ehwick]

Thanks for the tip! I'll give that a shot in the morning. However, the spraying carb cleaner may not be a viable option. The engine doesn't sputter and then stop. It just shuts off like you used the ignition key. Another thought: Since this only happens when it gets colder out, could it be a engine temp sensor that is going wacky? (although the engine temp never goes above the halfway mark)

[avguy]

...The engine doesn't sputter and then stop. It just shuts off like you used the ignition key ...

When I pulled the fuel pump relay in doing a baseline compression test on my '05 a few years ago, I don't recall any sputtering or struggling to stay running. Not saying it's fuel-related, just that it's one really easy diagnostic test which should be able to either rule out, or confirm fuel as the issue.

...could it be a engine temp sensor that is going wacky?...

You have an unusual set of symptoms, and IMO nothing should be ruled out until testing proves it to be ok. If carb cleaner doesn't keep it running, next I'd try gently moving all of wiring around a bit, right after the cold start up. Doing that could potentially flush out a bad connector or wire, if the pattern of the stall is changed by doing that.

[xintersecty]

Since this only happens when it gets colder out, could it be a engine temp sensor that is going wacky?

This is why you need a scanner. If you have a smart phone:
https://www.amazon.com/Panlong-Bluet...nner+bluetooth

It takes a running engine before a code is recorded. However if the temp sensor spiked when cold it would have show up in the scanner values. A scanner shows you the values, and allows a human to understand the data. Also by having information it will keep you from asking WHAT IF questions.

Come on' let's use some science and MEASURE it!

[xintersecty]

One minute of cold warmup is right in the ballpark time for the ecu to close the loop, so there's one very quick and easy test you can try, in order to see if this is closed loop-related. Just remove the upstream O2 sensor connector before doing the first cold start. That will force the ecu to stay in open loop, and you'll find out if it will keep running in that mode. If it stays running, then the issue is something which participates in closed loop processing.

But if it still stalls the same way with the sensor disconnected, then confirm it's not being starved for fuel by spraying a small bit of carb cleaner into the intake, right at the time it begins to stall.

BTW you need to be listening to avguy. He knows his stuff and gives you easy diagnostics to follow.