Mechanics

ROUGH IDLE

1999 Ford Contour

Engine Performance problem
1999 Ford Contour 4 cyl Two Wheel Drive Automatic 147000 miles

I have a 1999 Ford contour that recently began to idle extremely roughly, to the point of stalling if I do not apply slight pressure on the accelerator while stopped. It runs perfectly fine while driving though. Also, it makes a loud hissing noise, like a high pressure air leak somewhere around the airbox. I have read on here that it may be the idle air control unit. Can you confirm this based on my description?

Thank you
Avatar
AcesFull
November 7, 2008.




If ou can hear a whistle, you most likely have a vacuum leak. Inspect the vacuum lines carefully and look for any that may have popped off the intake. If you cant see anything, try carefully spraying carb cleaner around the engine, when you hit the leak, the engne will change

Tiny
Jack42
Nov 7, 2008.
Thanks for the reply. I went out and checked for any lines that may have popped off and found none. I am at work right now so I do not have access to the carb cleaner, that will have to wait till I get home. Something else that I noticed is that when you first start the car, the hissing is there but low pitched and the idle is OK. After driving for a while, the idle gets bad and the hissing loud. I would think that if there was a leak, it would be more constant. Again, thanks for the reply.
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Tiny
AcesFull
Nov 7, 2008.
It could very well be the Idle Air Control Valve then, but check for leaks first

Tiny
Jack42
Nov 7, 2008.
I'm going to leave work in an hour or so. I have to drive 70 miles home, so hopefully the car will make it. Like I said, it drives fine once it gets going past idle. Thanks for the help, I'll post up the results of the solution.

Tiny
AcesFull
Nov 7, 2008.
Well, the car made it home, although it died twice in the middle of 2 long left hand turns through some pretty big intersections. As soon as I got home, I popped the hood and grabbed a can of carb cleaner off the shelf and began lightly spraying around the area I thought I heard the sound. Sure enough, the idle change drastically. I pulled the air box and resonator off to see better but still couldn't find anything. Finally, I put it on jackstands and took a look from the bottom. From the bottom you can see the underside of the intake manifold, which had a tube, roughly 3/8" to 1/2" ID, connected that ran up and around and into the blck somewhere. There was a large tear in the tube, actually, it looked like the tube finally had just collapsed on itself. It is not a rienforced tube but rather just a rubber tube, which actually had 2 different sizes on each end. I couldn't identify it with my manuals, nor could Autozone or Kragen, so I went to the local Ford dealership. They cross-referenced the identification markings on the tube and told me it was a PCV tube. They ordered me a new one which should be in tomorrow morning. I appreciate the tip of using the carb cleaner to locate the leak, it probably saved me some cash. Thanks.

Tiny
AcesFull
Nov 7, 2008.

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