Rough startup idle when the weather is very cold?

YAZIDAN

MEMBER
2007 TOYOTA COROLLA
1.8L
4 CYL
2WD
AUTOMATIC
240,000 MILES

When the weather is very cold in winter only. on startup sometimes the car does not go too high idle. It idles low around 1,000 and the engine is rough. one day it came out from the engine white smoke with gas smell. I just watched a video from a Toyota mechanic he said that when see white smoke is sign of cylinder wash down. is it true?

This is the link:

https://youtu.be/V02O8YGuc4U?si=0IkKO6LMS_O4-uxu

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

White smoke can be a few things. For example, steam on a cool day, coolant getting into the combustion chamber, or what you mentioned.

The idea that this only happens when it is cold leads me to question if the engine coolant temperature sensor is working properly. The computer uses the signal from the sensor to determine how to mix the air/fuel ratio for the best engine performance. If it tells the computer the temperature is 80 degrees F and it is only 20 degrees F, the vehicle will run poorly until it warms up.

Has the check engine light ever turned and stayed on? Also, by chance do you have a live data scan tool?

Let me know.

Joe

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Sunday, July 21st, 2024 AT 7:49 PM

YAZIDAN

MEMBER
107 POSTS

I compared the coolant temperature with air temperature sensor they matched. Also, the white smoke was fuel. It smelled of fuel, not coolant or steam. Yes, I have a code reader with live data. No check engine light never came on.

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Sunday, July 21st, 2024 AT 11:13 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

If it was a fuel smell, connect the scanner to the DLC. Allow the engine to warm up to operating temperature and check the short term fuel trims. That will tell us if it is getting too much fuel or not.

Let me know.

Joe

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Monday, July 22nd, 2024 AT 8:17 PM