Engine idling rough with a misfire, when I turn the heater on the engine shuts off

Tiny
MONIKANME1
  • MEMBER
  • 2011 CADILLAC CTS
  • 3.6L
  • V6
  • 2WD
  • AUTOMATIC
  • 63,000 MILES
When my car is running it's idling hard with a slight misfire. When I turn my heater on the whole engine shuts off. I have to put the transmission in park and turn the heater off for it to start, what could my problem be?
Monday, January 31st, 2022 AT 7:45 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,645 POSTS
Hi,

This sounds like either an engine vacuum leak issue or the idle air control valve is failing.

Do me a favor. See if the same thing happens when you turn the A/C on. Also, pay attention to see if when this happens, the defroster is on.

Also, take a look through this link. It explains how to locate and repair an engine vacuum leak. If you don't find any, we will need to dig a bit further into the idle air control valve. That component is located on the throttle body and is responsible for maintaining the engine's idle speed.

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

Take a look through this link as well. It explains how the IAC works and what it does.

https://www.2carpros.com/articles/how-a-idle-air-control-valve-works

Let me know as much as you can. And hang in there. We'll get it fixed.

Take care,

Joe
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Monday, January 31st, 2022 AT 8:31 PM

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