Idles until warm

STEVEN BARNETT

MEMBER
1997 MERCURY COUGAR
4.6L
V8
2WD
AUTOMATIC
250,000 MILES

I just bought this car that had been setting for three years. I put fresh gas in on top of the old. It stated right up with a hot battery and I drove it home. I was concerned about the stale gas so I filled it up and added Seafoam and let it idle. After idling for about forty five minutes the car quit running and would not start. I waited a day and it started right up, but again shut off after about forty five of idling. The motor is not getting hot, oil and coolant looks good. It will start with starting fluid, but shuts off again after that burns off unless you rev up the engine, but when it returns to an idle it shuts off again. There is a foam connector at the PCV valve that looks like it might be original and possibly sucking air. Could this be my problem? If not, any other ideas would be helpful. Thanks

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,313 POSTS

Yes a vacuum leak can cause the engine to stall at idle. Here is a guide to help us get started which shows other problem that can cause you problem:

https://www.2carpros.com/articles/stall-at-idle

and

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

Please run down these guides and report back.

Cheers, Ken

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Monday, August 13th, 2018 AT 2:49 PM

STEVEN BARNETT

MEMBER
5 POSTS

I was wrong, what I thought was PCV valve was only a connector. I did replace the hose on it though. Also cleaned the throttle body with carburetor cleaner. After reading your reply, I checked all vacuum connections with no variance in idle speed. It did still stall out after about forty five minuted of idling and would not start without starting fluid. My neighbor, who is a part-time mechanic suggested the air flow controller (not sure exactly what he called it, I will attach picture of it). We will be hooking up to a diagnostic computer shortly but waiting on another neighbor to help out. Engine runs and accelerates great until around the forty five minute mark.

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Monday, August 13th, 2018 AT 3:37 PM

STEVEN BARNETT

MEMBER
5 POSTS

Okay, cannot figure out how to add pictures, but it is a small electrical box just after the air filter in the plenum. And it shut off after fifteen minutes this time.

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Monday, August 13th, 2018 AT 3:43 PM

KEN L

MASTER CERTIFIED MECHANIC
48,313 POSTS

Use the image upload link here at the bottom of the text box to the left. It sounds like you have an engine coolant temperature sensor that is not working right. Here is a guide to help you see what you are in for when doing the job and a diagram to show you where is it in your car:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken

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Tuesday, August 14th, 2018 AT 10:24 AM

STEVEN BARNETT

MEMBER
5 POSTS

We hooked it up to the computer and got code p0320. For 90% of vehicles that is a crank shaft sensor. The part was $30.00 and my neighbor charged $30.00 labor. It took him about one hour to change. I let the car idle for about an hour before driving. I shut it off and restarted several times after that hour. I have been taking short drives and not had any problems. Thank you for your help, but you missed the mark this time.