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Very low idling during cold start?

Tiny
YAZIDAN
  • MEMBER
  • 2007 TOYOTA COROLLA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 241,000 MILES
Very low idling during cold start only when outside temp is very low. What can be the causes?
Tuesday, December 5th, 2023 AT 11:20 PM

16 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,254 POSTS
Hi,

When this happens, how low is the idle in comparison to when it is warmer outside? Does the idle speed return to normal when the engine warms up? Is the check engine light staying on while the engine is running?

This could be the result of a few things. Because things contract when they cool on an engine, you could have a vacuum leak. Also, the engine coolant temperature sensor may not be sending a proper signal to the computer.

Let me know as much as you can.

Joe
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Wednesday, December 6th, 2023 AT 8:05 PM
Tiny
YAZIDAN
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Less than 1,000 RPMs. When it's warmer outside it's normal, it does fast idle first at 1,500-2,000 after will go down.
But when it's cold it does not go to 1,500-2,000. No check engine light no flashing check engine light and no codes.
When that happens, I will shut off the engine and after a few attempts it does fast idle at 1500-2000. I believe if I do not shut off the engine the fast idle will go up slowly to 1500-2000. Also, when it happens, I smell a very strong gas smell.
Also, when that happens, I tried to push the gas pedal to see if the fast idle goes up, but it does not.
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Thursday, December 7th, 2023 AT 2:14 AM
Tiny
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Hi,

The high idle is computer-controlled. My concern is the fuel smell. Does it smell like raw fuel or are you referring to the exhaust fumes?

Have you checked for fuel leaks when this happens?

Let me know.

Joe
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Thursday, December 7th, 2023 AT 8:13 PM
Tiny
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  • 91 POSTS
One day white smoke came from the engine because the exhaust donut is leaking but has exhaust fumes smell not anti-freeze smell or gas smell. Yes, no fuel leaks.
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Friday, December 8th, 2023 AT 6:21 AM
Tiny
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  • MECHANIC
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Hi,

The idea that it doesn't smell like raw fuel or coolant leads me to think either you are getting an air/fuel mixture that is too lean or one that is too rich.

By any chance, do you have a live data scan tool? If you do, could you check the signal from the coolant temperature sensor before starting the vehicle? It should be very close to ambient temperatures. Also, after the vehicle reaches operating temperature, let me know what the short-term fuel trims are.

If you don't have a scan tool that can do this, let me know. My concern is that I suggest you simply replace the parts and find out that wasn't the problem. If you could provide the aforementioned information, it would help guide me.

Let me know.

Take care,

Joe
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Friday, December 8th, 2023 AT 9:45 PM
Tiny
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  • 91 POSTS
The car was in the garage all night. The outdoor temperature not inside the garage was 25F. The coolant temp was 54 F. The intake air temperature was 57F. I started the car. The car went very quickly on closed loop at the beginning when the car was still cold and running long term was +7 and short term was -7. When the coolant temperature was 199 F long term was +15.6 and short term was between - 0.8 and +1.6. No heck engine light no codes and the car high idled normally today.
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Saturday, December 9th, 2023 AT 4:20 PM
Tiny
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Hi,

The trims look good. The temperature sensors appear to be working. Have you tried cleaning the throttle body? If not, that may take care of the issue.

First, here is a link that explains common symptoms, look through it and let's see if anything mirrors what you are experiencing:

https://www.2carpros.com/articles/common-symptoms-of-a-dirty-car-throttle-body-a-comprehensive-guide

If you feel there are things similar, here is the link to service it:

https://www.2carpros.com/articles/throttle-actuator-service

Let me know your thoughts.

Take care,

Joe
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Saturday, December 9th, 2023 AT 10:44 PM
Tiny
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  • MEMBER
  • 91 POSTS
Yes, I did clean throttle body several times. Can it be issues with injectors or other components of the fuel system? (I put several times injectors cleaner Berryman B12 in tank). What about that white smoke that came out when idle was low instead of higher idle? What does that indicate? I checked today again the reading of ECT sensor temperature is 52 F and intake air temperature is 55F.
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Sunday, December 10th, 2023 AT 5:56 AM
Tiny
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Hi,

When you check and find the temp similar to the ambient temp, do you experience the issue? Also, when you say white smoke, it is likely steam from the exhaust. However, if it is a thick white smoke that has a sweet smell to it, that could indicate coolant is getting into the combustion chamber due to a failed head gasket.

How would you best describe the smoke you referred to?

Joe
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Sunday, December 10th, 2023 AT 7:36 PM
Tiny
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  • 91 POSTS
Today when I checked the temperature of both sensors they were almost equal and I did not experience the issue. The smoke had a gas smell/exhaust fumes came from engine exactly from the exhaust donut because the car has a leaky donut gasket. I am sure it is not coolant; it happens only once. Today I parked the car outside I will check again.
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Sunday, December 10th, 2023 AT 8:01 PM
Tiny
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  • 91 POSTS
Okay, the car sat all night outside. In the morning before I started the car, I checked the coolant sensor and air intake sensor they were both at 34F and I experienced the issue. The car at first idle at 1,000 RPMs and was running poorly. So, I taped on the gas pedal twice and the rpm went up from 1,000 to 1,600 and the car ran normally after that. I did not see smoke or smell gas.
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Monday, December 11th, 2023 AT 5:54 AM
Tiny
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Hi,

I have a feeling it is a vacuum leak that stops leaking when the metal starts expanding as it runs. If everything other is working correctly, they appear to be, that is what I suggest looking for while the problem is occurring.

Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know.

Joe

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Monday, December 11th, 2023 AT 8:13 PM
Tiny
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Okay, I will check for vacuum leaks when its cold and I will clean again the throttle body . this time i will unbolted it and clean it. what is the safest way the clean it. can I open the flap by hand ?. I saw a Toyota mechanic he says that we can open it by hand . because there is no computer in it . there are just a motor and gears . but he says just open it slowly
https://www.youtube.com/watch?v=3B-a8WJtd8w
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Tuesday, December 12th, 2023 AT 5:57 AM
Tiny
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Hi,

It should be okay to service it.

Here is a link that explains what to do:

https://www.2carpros.com/articles/throttle-actuator-service

Let me know if this helps.

Take care,

Joe
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Tuesday, December 12th, 2023 AT 6:42 PM
Tiny
YAZIDAN
  • MEMBER
  • 91 POSTS
Hi,

sorry for asking again. When cleaning it. Can I move the butterfly by hand, to clean it's both edges? After unbolting it and disconnect the TB electrical wire.
Last time when I did it. I did not unbolt it and I asked someone to push the gas pedal while I cleaning it.
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Wednesday, December 13th, 2023 AT 6:17 AM
Tiny
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Hi,

No problem whatsoever. Yes, you should be fine to do that. Just be gentle on it and move it slowly.

Take care,

Joe
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Wednesday, December 13th, 2023 AT 7:02 PM

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