Vehicle will not start in cold weather?

2001 CHEVROLET TAHOE
150,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
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KNOXSEMENZA
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It cranks nice and strong but that's all it does. The fuel pump has been replaced recently and I replaced the fuel injection pressure regulator thinking it was that as well. Once I put a heater in the engine bay for a couple minutes, it fires right up. Could it be the idle air control valve sticking? It only needs a little heat to fire up. Any help would be great.
Nov 18, 2022 at 12:30 AM
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JACOBANDNICKOLAS
  • Experienced Mechanic
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Hi,

By chance, does the check engine light stay on while the engine is running? If it does, have you scanned it for codes?

The idea that it won't start in cold weather can be a few things. The PCM uses information from the ECT (engine coolant temperature sensor) to determine what the air/fuel mixture should be to start the engine based on temp. I'm questioning if that could be an issue.

Do you have a live data scan tool? If you do, before starting the engine in the morning, check to see what signal the ECT is sending. It should be very close to the ambient temperature outside.

Also, let me know how cold the weather is where you are located and more importantly if the check engine light stays on with the engine running. If it is, have the computer scanned. If you don't have a scan tool, most parts stores will do it free of charge.

Here is a quick video showing how it's done:

https://youtu.be/b2IJGfImVvw

One other thought is the intake air temperature sensor/mass air flow sensor. It is used by the PCM as well for cold starts. This should set a code if there is an issue. If there is no CEL, then again, we need a live data scan tool to confirm it is sending the correct info.

Also, if the IAC was the cause, it would happen regardless of the temperature. If you suspect the IAC, slightly touch the gas pedal when cranking to see if it makes a difference.


One last thought. When were the spark plugs last replaced?

Let me know.

Joe
Nov 18, 2022 at 12:56 PM
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KNOXSEMENZA
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I was going to replace the spark plugs to see if that helped and I thought of doing the coolant temperature sensor. There is no engine light that comes up and no codes come up. Thanks for all the helpful information, I will try the coolant temperature sensor and spark plugs. And it happens usually below zero. This morning when I tried it was -14.
Nov 18, 2022 at 1:26 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
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OMG! I wouldn't start either. LOL That is cold. I'm near Pittsburgh and thought 20 tonight was bad. At least I'm not near Erie where they are expecting five feet of lake-effect snow.

Regardless, let me know if this helps.

Take care and stay warm.

Joe
Nov 18, 2022 at 3:01 PM
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KNOXSEMENZA
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Ya it's cold! And I will, thanks!
Nov 18, 2022 at 10:57 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
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Hi,

I haven't heard from you for a couple of days. Have you been able to make any progress? I'm interested in knowing.

Hope all is well.

Joe
Nov 21, 2022 at 10:17 AM
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KNOXSEMENZA
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Not yet, I'll let you know when.
Nov 21, 2022 at 11:17 AM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
No problem whatsoever. Take care. If I don't hear from you, I hope you have a good Thanksgiving.

Joe
Nov 21, 2022 at 11:38 AM
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